152 results on '"Ngeow Yf"'
Search Results
2. Young Malaysian children with lower respiratory tract infections show low incidence of chlamydial infection
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NGEOW, YF, primary, WEIL, AF, additional, KHAIRULLAH, NS, additional, YUSOF, MY MOHD, additional, LUAM, L, additional, GAYDOS, C, additional, and QUINN, TC, additional
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- 1997
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3. Transcutaneous Po2 as a Trend Indicator of Arterial Po2 in Normal Anesthetized Adults
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Nardi D, Marrero O, Mentelos R, Terence D. Rafferty, Ngeow Yf, and Schachter En
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Anesthesiology and Pain Medicine ,integumentary system ,business.industry ,Anesthesia ,Arterial pO2 ,Normal cardiovascular function ,Medicine ,Anesthetic Agent ,business - Abstract
The transcutaneous technique of measuring PO2 (tcPO2) was studied in 30 adults with normal cardiovascular function undergoing nitrous oxide-enflurane or nitrous oxide-fentanyl anesthesia to determine the relationship between tcPO2 and PaO2. The tcPO2 was an accurate and clinically useful trend indicator of PaO2 (r = 0.9; p less than 0.0001). The ability to detect trends was unaffected by the type of anesthetic agent used. The technique was less useful in predicting absolute values for PaO2 (r = 0.86). It is suggested that more widespread application of such monitoring awaits definitive development of a halothane-resistant electrode.
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- 1982
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4. Rectal microscopy in men - expensive, time consuming and inappropriate.
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Sam Ic, Ngeow YF, Waters, Laura, Worthen, Elaine, and O'mahony, Colm
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- 2006
5. Oncolytic measles virus-induced cell killing in radio-resistant and drug-resistant nasopharyngeal carcinoma.
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Looi HK, Ngeow YF, Kiew LV, Chang LY, and Ong HT
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- Humans, Cell Line, Tumor, Carcinoma therapy, Cisplatin pharmacology, Oncolytic Viruses, Radiation Tolerance, Antineoplastic Agents pharmacology, Nectins, Measles virus, Nasopharyngeal Neoplasms virology, Nasopharyngeal Neoplasms therapy, Nasopharyngeal Neoplasms pathology, Oncolytic Virotherapy methods, Nasopharyngeal Carcinoma virology, Nasopharyngeal Carcinoma therapy, Nasopharyngeal Carcinoma pathology, Drug Resistance, Neoplasm
- Abstract
Introduction: The current first-line therapy for nasopharyngeal carcinoma (NPC) is often associated with long-term complications. Oncolytic measles virus (MV) therapy offers a promising alternative to cancer therapy. This study aims to investigate the efficacy of MV in killing NPC cells in vitro, both with or without resistance to radiation and drug therapy., Materials and Methods: NPC cell lines, CNE-1, CNE-2, HONE-1 and C666-1, were exposed to repeated cycles of gamma-irradiation and cisplatin to establish radio- and chemo-resistant cell lines, respectively. The expression of MV receptors, CD46 and nectin-4, were assessed with flow cytometer. To test the efficacy of viral infection, parental and both resistant NPC cells were infected with Measles-GFP-NIS in vitro. The progress of syncytia spread on NPC cells was monitored with fluorescence microscopy up to 60-hours post-infection (p.i.). MV-mediated killing was assessed using tetrazolium-based cell viability assay., Results: We established cisplatin-resistant (CR) NPC cell lines that exhibit more than two-fold shift in IC50 against cisplatin. Only CNE-2 and C666-1 acquired resistant traits after a cumulative 60-Gy gamma irradiation. All untreated parental and resistant NPCs expressed CD46 but not nectin-4 on their cell surface and were susceptible to MV infection. Syncytia were observable as early as 24 hours p.i. and cell loss was observable at 48-hours p.i. onwards. Interestingly, Measles-GFP-NIS shows higher infectivity in NPC with resistance phenotypes, except in CR-C666-1, and were killed more compared to their non-resistant counterparts., Conclusion: Measles-GFP-NIS demonstrated potential as an alternative treatment in relapse, recurrent, or advanced stage NPC which often exhibits resistance towards chemo- and radiotherapy.
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- 2024
6. In vitro analysis of VEGF-mediated endothelial permeability and the potential therapeutic role of Anti-VEGF in severe dengue.
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Lim SJ, Gan SC, Ong HT, and Ngeow YF
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Background: Vascular endothelial growth factor (VEGF) is one of the proteins involved in dengue immunopathogenesis. It is overexpressed in severe dengue and contributes to vascular permeability and plasma leakage. In this study, we investigated the effects of VEGF and anti-VEGF treatments on endothelial cells in vitro, to assess the potential use of anti-VEGF antibodies in managing severe dengue., Methods: Human pulmonary microvascular endothelial cells were treated with VEGF and a VEGF/anti-VEGF combination. The effects of the treatments were studied using an endothelial permeability assay and microarray gene expression profiling. In the permeability assay, the fluorescein isothiocyanate (FITC)-dextran fluorescence signal across the endothelial monolayer was recorded, and the cells were stained with PECAM-1 to detect gap formation. RNA was extracted from treated cells for microarray gene profiling and analysis. The results were analyzed for differentially expressed genes (DEGs) and gene enrichment analysis. The DEGs were subjected to STRING to construct the protein-protein interaction network and then Cytoscape to identify the hub genes., Results: VEGF-treated endothelial cells showed greater movement of FITC-dextran across the monolayer than VEGF/anti-VEGF-treated cells. There were 111 DEGs for VEGF-treated cells and 118 DEGs for VEGF/anti-VEGF-treated cells. The genes upregulated in VEGF-treated cells were enriched in inflammatory responses and regulation of the endothelial barrier, nitric oxide synthesis, angiogenesis, and the nucleotide-binding oligomerization domain-like receptor signaling pathway. Top 10 hub genes were identified from the DEGs., Conclusions: VEGF treatment increased permeability across endothelial cells, while anti-VEGF reduced this leakage. Analysis of VEGF-treated endothelial cells identified hub genes implicated in severe dengue. The top 10 hub genes were TNF, IL1B, IL6, CCL2, PTGS2, ICAM1, CXCL2, CXCL1, CSF2, and TLR2. The results of this study show that using anti-VEGF antibodies to neutralize VEGF may be a promising therapy to prevent the progression of dengue to severe dengue., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors. Published by Elsevier B.V.)
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- 2024
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7. The positive impact of Streptococcus mutans on the growth of Candida albicans within mixed-species biofilms and implications to dental health.
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Wang X, Yap SF, and Ngeow YF
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- Humans, Oral Health, Mouth microbiology, Biofilms growth & development, Candida albicans growth & development, Candida albicans physiology, Streptococcus mutans growth & development, Streptococcus mutans physiology
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Introduction: Candida albicans and Streptococcus mutans co-exist in biofilms in the oral cavity. In this study, the impact of S. mutans on the growth of C. albicans within a mixed-species biofilm was examined., Materials and Methods: Single species C. albicans biofilms and mixed species biofilms containing C. albicans and S. mutans at 1:3 and 1:10 ratios were constructed in 6-well microtiter plates. After 24 hours of incubation, the density of resuspended biofilm cells was determined as CFU/ml and used to compare the growth of C. albicans in single species and mixed species biofilms., Results: The CFU/ml of C. albicans in mixed-species biofilms was found to be higher than that in single-species biofilms., Conclusion: S. mutans promotes the growth of C. albicans in a co-inhabited biofilm.
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- 2024
8. Navigating the intricacies of RT-qPCR data analysis in gene expression studies.
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Wetthasinghe L, Ng HF, Ngeow YF, Chew KS, and Lee WS
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- Humans, Real-Time Polymerase Chain Reaction standards, Real-Time Polymerase Chain Reaction methods, Data Analysis, Gene Expression Profiling methods
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- 2024
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9. Cardiac and Neurological Complications Post COVID-19 Vaccination: A Systematic Review of Case Reports and Case Series.
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Lee KW, Yap SF, Amin-Nordin S, and Ngeow YF
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Following mass vaccinations for the control of the COVID-19 epidemic, a spectrum of cardiac and neurological disorders was reported among vaccinated individuals. This study examined the range of complications documented and factors related to their occurrence. Three electronic databases were searched for case reports and case series with descriptions of cardiac and/or neurological complications in COVID-19 vaccine recipients. A total of 698 vaccinees were included in this review, of which 259 (37.1%) had cardiac and 439 (62.9%) had neurological complications. Inflammatory conditions were the commonest among the cardiac complications; while polyneuropathy, demyelinating diseases and cerebrovascular disorders were the more common neurological complications. The mean age of those with cardiac complications (33.8 years) was much younger than those with neurological complications (49.7 years). There was no notable difference in the gender distribution between these two groups of vaccine recipients. mRNA vaccines (all brands) were associated with almost 90.0% of the cardiac complications, whereas viral vector vaccines were associated with slightly over half (52.6%) of the neurological complications. With regard to the dose, cardiac complications were more common after the second (69.1%), whereas neurological complications were more common after the first dose (63.6%). The majority of the cases had an uncomplicated clinical course. Nevertheless, 5.9% of cases with neurological complications and 2.5% of those with cardiac complications were fatal, underscoring the significance of the consistent surveillance and vigilant monitoring of vaccinated individuals to mitigate these occurrences., Competing Interests: The authors declare no conflicts of interest.
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- 2024
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10. Five-year species distribution and antimicrobial susceptibility of non-tuberculous mycobacteria in Malaysia, 2018-2022.
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Mohamad Azranyi M, Aziz ZA, Ishak D, Mohd Nais NF, Elias ZA, Sulaiman NAF, Hashim KA, Ismail R, Nik Mahir NJ, Ngeow YF, and Zin T
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- Humans, Retrospective Studies, Malaysia epidemiology, Anti-Bacterial Agents pharmacology, Nontuberculous Mycobacteria, Mycobacterium Infections, Nontuberculous epidemiology, Mycobacterium Infections, Nontuberculous microbiology
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Introduction. Non-tuberculous Mycobacteria (NTM) is a group of mycobacteria distinct from the Mycobacterium tuberculosis complex. They can cause opportunistic infections, especially in immunocompromised individuals. Gap Statement. Over the last few years, there has been a growing concern regarding the distribution and antimicrobial resistance of NTM in Malaysia. however, a comprehensive study to fully grasp the NTM situation has yet to be conducted. Aim. This study aimed to investigate the species distribution and antimicrobial susceptibility patterns of NTM isolated from clinical samples in Malaysia from 2018 to 2022. Methodology. A retrospective analysis was conducted on NTM isolates obtained from various clinical specimens over a span of five years. The isolates were identified using phenotypic and molecular techniques, and antimicrobial susceptibility profiles for clinically significant isolates were determined using minimum inhibitory concentration. Results. The study revealed a diverse distribution of NTM species in Malaysia, with Mycobacteroides abscessus complex and Mycobacterium avium complex emerging as the most predominant. Furthermore, the antimicrobial susceptibility patterns showed varying degrees of resistance to commonly used antibiotics, highlighting the significance of treatment tailored to susceptibility testing results. Conclusion. This study provides valuable perspective into the epidemiology of NTM in Malaysia. The information gained from this study should prove useful for empirically treating serious NTM infections prior to species identification and the availability of antimicrobial susceptibility testing results.
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- 2024
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11. The association between VSX1 exon3 gene variants and keratoconus in Malaysian patients.
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Deva JP, Ngeow YF, and Zin T
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- Humans, Asian People genetics, Case-Control Studies, Eye Proteins genetics, Homeodomain Proteins genetics, Keratoconus diagnosis, Keratoconus epidemiology, Keratoconus genetics
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Purpose: This case-control study aims to examine possible associations of VSX1 exon3 gene variants with the development of keratoconus (KC) in Malaysian patients., Methods: A case-control study was done on 42 keratoconus cases, 127 family member controls, and 96 normal controls., Results: Three gene variants, p.A182A, p.P237P, and p.R217H showed significant associations with keratoconus (P < 0.05). While p.A182A and p.P227P were more prevalent than in the family and normal controls (OR 3.14-4.05), the reverse was observed with p.R217H (OR 0.086-1.59). With Haploview analysis, p.A182A and p.P237P were shown to be in linkage disequilibrium (LD) (LOD (logarithm of the odds score) score of 2.0, r2 of 0.957, and 95% confidence interval (CI) of 0.96-1.00)., Conclusion: The study results suggest that the p.A182A and p.P237P variants could have contributed to the development of keratoconus in some Malaysians and that these two variants are likely to be co-inherited. In contrast, the p.R217H variant appeared to confer some protection against the development of keratoconus., Competing Interests: None
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- 2023
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12. Mechanisms of Linezolid Resistance in Mycobacteria.
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Gan WC, Ng HF, and Ngeow YF
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Mycobacteria form some of the most notorious and difficult-to-treat bacterial pathogens. As a group, they are intrinsically resistant to many commonly used antibiotics, such as tetracyclines and beta-lactams. In addition to intrinsic resistances, acquired multidrug resistance has also been observed and documented in Mycobacterium tuberculosis (MTB) , Mycobacterium leprae and non-tuberculous mycobacteria (NTM). To combat multidrug resistant infections by these pathogens, innovative antimicrobials and treatment regimens are required. In this regard, linezolid, an oxazolidinone introduced for clinical use just two decades ago, was added to the therapeutic armamentarium for drug-resistant mycobacteria. It exhibits antibacterial activity by binding to the 50S ribosomal subunit and inhibiting protein synthesis. Unfortunately, linezolid resistance has now been documented in MTB and NTM, in many parts of the world. Most linezolid-resistant mycobacterial strains show mutations in the ribosome or related genes, such as in the rplC, rrl and tsnR genes. Non-ribosomal mechanisms appear to be rare. One such mechanism was associated with a mutation in fadD32 , which encodes a protein that plays an important role in mycolic acid synthesis. Mycobacterial efflux proteins have also been implicated in linezolid resistance. This review summarises current knowledge of genetic determinants of linezolid resistance in mycobacteria, with the aim of contributing information that could facilitate the discovery of new therapeutic approaches to overcome, delay or avoid further developments of drug resistance among these important pathogens.
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- 2023
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13. Mutations in Genes Encoding 23S rRNA and FadD32 May be Associated with Linezolid Resistance in Mycobacteroides abscessus .
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Ng HF and Ngeow YF
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- Drug Resistance, Bacterial genetics, Linezolid pharmacology, Microbial Sensitivity Tests, Mutation genetics, RNA, Ribosomal, 23S genetics, Bacterial Proteins genetics, Anti-Bacterial Agents pharmacology, Mycobacterium abscessus genetics
- Abstract
Linezolid is one of the antibiotics used to treat the Mycobacteroides abscessus infection. However, linezolid-resistance mechanisms of this organism are not well understood. The objective of this study was to identify possible linezolid-resistance determinants in M. abscessus through characterization of step-wise mutants selected from a linezolid-susceptible strain, M61 (minimum inhibitory concentration [MIC]: 0.25 mg/L). Whole-genome sequencing and subsequent PCR verification of the resistant second-step mutant, A2a(1) (MIC: >256 mg/L), revealed three mutations in its genome, two of which were found in the 23S rDNA (g2244t and g2788t) and another one was found in a gene encoding the fatty-acid-CoA ligase FadD32 (c880t→H294Y). The 23S rRNA is the molecular target of linezolid and mutations in this gene are likely to contribute to resistance. Furthermore, PCR analysis revealed that the c880t mutation in the fadD32 gene first appeared in the first-step mutant, A2 (MIC: 1 mg/L). Complementation of the wild-type M61 with the pMV261 plasmid carrying the mutant fadD32 gene caused the previously sensitive M61 to develop a reduced susceptibility to linezolid (MIC: 1 mg/L). The findings of this study uncovered hitherto undescribed mechanisms of linezolid resistance in M. abscessus that may be useful for the development of novel anti-infective agents against this multidrug-resistant pathogen.
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- 2023
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14. Mutations in atpG2 may confer resistance to gentamicin in Listeria monocytogenes .
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Ng JML, Ngeow YF, Saw SH, Ng HF, and Zin T
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- Anti-Bacterial Agents pharmacology, Gentamicins pharmacology, Mutation, Listeria monocytogenes drug effects, Listeria monocytogenes genetics, Drug Resistance, Bacterial genetics
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Introduction Listeriosis, a foodborne infection caused by Listeria monocytogenes , could lead to febrile listerial gastroenteritis and a more invasive form which is often associated with a high mortality and hospitalisation rate. Gentamicin, used as an adjunct therapy with ampicillin, remains the treatment of choice for this life-threatening and invasive infection. Gap statement Nevertheless, there is little data on gentamicin resistance determinants in L. monocytogenes . Aim In this study, we selected and characterised B2b, a gentamicin-resistant mutant derived from L. monocytogenes ATCC 19115 to determine the target(s) of resistance in L. monocytogenes after exposure to gentamicin. Methodology Whole-genome sequencing was carried out to identify the mutation site(s) and possible mechanism(s) of resistance. The mutant was characterised using antimicrobial susceptibility testing and PCR. For biological verifications, complementation and allelic exchange mutagenesis were carried out. Results We found that the gentamicin resistance in B2b was caused by a 10 bp deletion in atpG2 which encodes a gamma subunit of the ATP synthase in L. monocytogenes . Using atpG2 PCR, various other mutations were identified in other gentamicin resistant mutants derived from ATCC 19115. In addition, the mutation from B2b, when introduced into L. ivanovii , also caused gentamicin resistance in this Listeria species. Conclusion Hence, atpG2 mutations appear to be important determinants of gentamicin resistance not only in L. monocytogenes but possibly also in other Listeria species.
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- 2022
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15. Hepatitis B virus DNA methylation and its potential role in chronic hepatitis B.
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Low WF, Ngeow YF, Chook JB, Tee KK, Ong SK, Peh SC, Bong JJ, and Mohamed R
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- Humans, Hepatitis B virus genetics, Hepatitis B virus metabolism, DNA Methylation, DNA, Viral genetics, DNA, Viral metabolism, DNA, Circular genetics, Hepatitis B, Chronic complications, Hepatitis B, Chronic genetics, Carcinoma, Hepatocellular etiology, Carcinoma, Hepatocellular genetics, Liver Neoplasms etiology, Liver Neoplasms genetics, Hepatitis B genetics
- Abstract
Hepatitis B virus (HBV) infection led to 66% liver deaths world-wide in year 2015. Thirty-seven per cent of these deaths were the result of chronic hepatitis B (CHB)-associated hepatocellular carcinoma (HCC). Although early diagnosis of HCC improves survival, early detection is rare. Methylation of HBV DNA including covalently closed circular DNA (cccDNA) is more often encountered in HCC cases than those in CHB and cirrhosis. Three typical CpG islands within the HBV genome are the common sites for methylation. The HBV cccDNA methylation affects the viral replication and protein expression in the course of infection and may associate with the disease pathogenesis and HCC development. We review the current findings in HBV DNA methylation that provide insights into its role in HCC diagnosis.
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- 2022
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16. The resistomes of Mycobacteroides abscessus complex and their possible acquisition from horizontal gene transfer.
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Chong SL, Tan JL, and Ngeow YF
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- Humans, Gene Transfer, Horizontal, Phylogeny, beta-Lactams, Anti-Bacterial Agents, Aminoglycosides, Mycobacterium abscessus genetics
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Background: Mycobacteroides abscessus complex (MABC), an emerging pathogen, causes human infections resistant to multiple antibiotics. In this study, the genome data of 1,581 MABC strains were downloaded from NCBI database for phylogenetic relatedness inference, resistance profile identification and the estimation of evolutionary pressure on resistance genes in silico., Results: From genes associated with resistance to 28 antibiotic classes, 395 putative proteins (ARPs) were identified, based on the information in two antibiotic resistance databases (CARD and ARG-ANNOT). The ARPs most frequently identified in MABC were those associated with resistance to multiple antibiotic classes, beta-lactams and aminoglycosides. After excluding ARPs that had undergone recombination, two ARPs were predicted to be under diversifying selection and 202 under purifying selection. This wide occurrence of purifying selection suggested that the diversity of commonly shared ARPs in MABC have been reduced to achieve stability. The unequal distribution of ARPs in members of the MABC could be due to horizontal gene transfer or ARPs pseudogenization events. Most (81.5%) of the ARPs were observed in the accessory genome and 72.2% ARPs were highly homologous to proteins associated with mobile genetic elements such as plasmids, prophages and viruses. On the other hand, with TBLASTN search, only 18 of the ARPs were identified as pseudogenes., Conclusion: Altogether, our results suggested an important role of horizontal gene transfer in shaping the resistome of MABC., (© 2022. The Author(s).)
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- 2022
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17. RshA mutations contributing to tigecycline resistance in Mycobacteroides abscessus .
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Aw KM, Ng HF, Lee CL, Zin T, and Ngeow YF
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- Anti-Bacterial Agents pharmacology, Bacterial Proteins genetics, Humans, Microbial Sensitivity Tests, Mutation, Sigma Factor genetics, Tigecycline pharmacology, Mycobacterium Infections, Nontuberculous, Mycobacterium abscessus genetics
- Abstract
Tigecycline is an important rescue antibiotic for many bacterial infections. In Mycobacteroides abscessus , tigecycline resistance has been associated with dysregulated stress response caused by aberrations in the interaction of the SigH and RshA factors. In this study, two tigecycline-resistant mutants of M. abscessus (CL5A and CL6A) with mutations in the rshA gene were studied using gene complementation, RT-qPCR and the bacterial adenylate cyclase two-hybrid (BACTH) system. The results supported the premise that mutations in the rshA interrupt the RshA-SigH interaction to cause the overexpression of the sigH gene that leads to tigecycline resistance or reduced susceptibility.
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- 2022
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18. Genetic Determinants of Tigecycline Resistance in Mycobacteroides abscessus .
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Ng HF and Ngeow YF
- Abstract
Mycobacteroides abscessus (formerly Mycobacterium abscessus ) is a clinically important, rapid-growing non-tuberculous mycobacterium notoriously known for its multidrug-resistance phenotype. The intrinsic resistance of M. abscessus towards first- and second-generation tetracyclines is mainly due to the over-expression of a tetracycline-degrading enzyme known as MabTetX ( MAB_1496c ). Tigecycline, a third-generation tetracycline, is a poor substrate for the MabTetX and does not induce the expression of this enzyme. Although tigecycline-resistant strains of M. abscessus have been documented in different parts of the world, their resistance determinants remain largely elusive. Recent work on tigecycline resistance or reduced susceptibility in M. abscessus revealed the involvement of the gene MAB_3508c which encodes the transcriptional activator WhiB7, as well as mutations in the sigH-rshA genes which control heat shock and oxidative-stress responses. The deletion of whiB7 has been observed to cause a 4-fold decrease in the minimum inhibitory concentration of tigecycline. In the absence of environmental stress, the SigH sigma factor ( MAB_3543c ) interacts with and is inhibited by the anti-sigma factor RshA ( MAB_3542c ). The disruption of the SigH-RshA interaction resulting from mutations and the subsequent up-regulation of SigH have been hypothesized to lead to tigecycline resistance in M. abscessus . In this review, the evidence for different genetic determinants reported to be linked to tigecycline resistance in M. abscessus was examined and discussed.
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- 2022
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19. Concentrated specimen smear microscopy utilising a polymer membrane sandwich filtration vessel for the detection of acid-fast bacilli in health facilities in Sabah, East Malaysia.
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Paul DC, Ngeow YF, Yap SF, Dony JF, Avoi R, Mohammad R, and Ng HF
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- Health Facilities, Malaysia, Polymers, Sensitivity and Specificity, Sputum, Microscopy methods, Mycobacterium tuberculosis, Tuberculosis diagnosis
- Abstract
A simple, ready-to-use concentrated specimen smear microscopy method employing a nanometer silicon polyvinylidene fluoride (PVDF) polymer membrane sandwich filtration vessel to concentrate acid-fast bacilli (AFB) in samples (SFV-CSSM, Hunan-Tech New Medical System Co. Ltd. China) was compared with direct sputum smear microscopy (DSSM) to determine its performance using culture on modified Ogawa agar as reference. The results for 4114 clinical samples collected from health facilities in Sabah were interpreted with reference to culture results, sample collection-transportation conditions and clinical data including responses to anti-TB drug treatment. The SFV-CSSM showed higher sensitivity than DSSM (79.4% versus 60.5%) and less background interference. Its ability to detect low levels of AFB at an affordable cost makes it an excellent tool for the screening of pauci-bacillary samples as well as for active case finding in TB control programs., (Copyright © 2022 Elsevier Ltd. All rights reserved.)
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- 2022
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20. A simple spreadsheet-based method for relative quantification using quantitative real-time PCR.
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Ng HF and Ngeow YF
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- Algorithms, Gene Expression Profiling methods, Humans, Real-Time Polymerase Chain Reaction methods, Research Design, Software
- Abstract
Relative quantification is a popular analysis in gene expression studies using quantitative real-time PCR (qPCR). However, the calculation steps using the major algorithms for this analysis are rather complicated. In this study, we developed an easy-to-use spreadsheet-based method for relative quantification. The inputs from end-users are the efficiencies of both target and reference genes and the C
q values of those genes from cases and controls. This method performed normalization (with one or more reference genes), calculation of fold change of gene expression, and statistical analysis to analyze the difference between the groups in a step-by-step manner, which would allow the end-users to understand how the analysis arrived at the conclusion. Four previously published data sets with different experimental designs were used as examples. The calculated results were concordant with the results computed by the Relative Expression Software Tool (REST) 2009, a popular tool for relative quantification. Altogether, our method, which offers easy-to-understand calculation steps and does not require specialized instruments, software, or expertise to operate, would be a useful tool for students, educators, and scientists in the field of molecular biology., (© 2021 International Union of Biochemistry and Molecular Biology.)- Published
- 2022
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21. Genomic diversity of SARS-CoV-2 in Malaysia.
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Mohamad Noordin N, Tan JL, Chong CK, Chem YK, Tajudin N, Abu Bakar RS, Sengol S, Phoon HYP, Che Azid NAM, W Mohd Arifin WNA, Aziz ZA, Hussin H, Ibrahim NS, Omar A, Ravi U, Kamarul Zaman KH, Yamin MA, and Ngeow YF
- Abstract
Background: More than a year after its first appearance in December 2019, the COVID-19 pandemic is still on a rampage in many parts of the world. Although several vaccines have been approved for emergency use, the emergence and rapid spread of new SARS-CoV-2 variants have sparked fears of vaccine failure due to immune evasion. Massive viral genome sequencing has been recommended to track the genetic changes that could lead to adverse consequences., Methods: We sequenced SARS-CoV-2 respiratory isolates from the National Public Health Laboratory, Malaysia and examined them together with viral genomes deposited in GISAID by other Malaysian researchers, to understand the evolutionary trend of the virus circulating in the country. We studied the distribution of virus lineages and site-wise mutations, analysed genetic clustering with the goeBURST full Minimum Spanning Tree algorithm, examined the trend of viral nucleotide diversity over time and performed nucleotide substitution association analyses., Results: We identified 22 sub-lineages, 13 clonal complexes, 178 sequence types and seven sites of linkage disequilibrium in 277 SARS-CoV-2 genomes sequenced between January and December 2020. B.1.524 was the largest lineage group. The number of mutations per genome ranged from 0 to 19. The mean genomic diversity value over 12 months was 3.26 × 10
-4 . Of 359 mutations detected, 60.5% of which were non-synonymous, the most frequent were in the ORF1ab (P4715L), S (D614G and A701V) and N (S194L) genes., Conclusion: The SARS-CoV-2 virus accumulated an abundance of mutations in the first year of the COVID-19 pandemic in Malaysia. Its overall genetic diversity, however, is relatively low compared to other Asian countries with larger populations. Continuous genomic and epidemiological surveillance will help to clarify the evolutionary processes determining viral diversity and impacting on human health., Competing Interests: The authors declare there are no competing interests., (©2021 Mohamad Noordin et al.)- Published
- 2021
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22. A stop-gain mutation in sigma factor SigH (MAB_3543c) may be associated with tigecycline resistance in Mycobacteroides abscessus .
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Lee CL, Ng HF, Ngeow YF, and Thaw Z
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- Genome, Bacterial, Mutation, Whole Genome Sequencing, Anti-Bacterial Agents pharmacology, Bacterial Proteins genetics, Drug Resistance, Bacterial genetics, Mycobacterium abscessus drug effects, Mycobacterium abscessus genetics, Sigma Factor genetics, Tigecycline pharmacology
- Abstract
Introduction. Tigecycline is currently acknowledged to be one of the most effective antibiotics against infections caused by Mycobacteroides abscessus . Gap statement. The genetic determinants of tigecycline resistance in M. abscessus are not well understood. Aim. In this study, we characterized a tigecycline-resistant M. abscessus mutant, designated CL7, to identify the potential resistance mechanism. Methodology. CL7 was characterized using antimicrobial susceptibility testing, whole-genome sequencing, PCR and RT-qPCR. For biological verification, gene overexpression assays were carried out. Results. Whole-genome sequencing and the subsequent gene overexpression assays showed that CL7 harboured a stop-gain mutation in MAB_3543 c, which may be responsible for the tigecycline resistance phenotype. This gene encodes an orthologue of SigH, which is involved in the positive regulation of physiological stress response and is negatively regulated by the RshA anti-sigma factor in Mycobacterium tuberculosis . We hypothesized that the MAB_3543 c mutation may disrupt the interaction between SigH and RshA (MAB_3542 c). RT-qPCR analyses revealed the upregulation of MAB_3543 c and other key stress response genes, which has previously been shown to be a hallmark of SigH-RshA bond disruption and tigecycline resistance. Conclusion. The MAB_3543c mutation may represent a novel determinant of tigecycline resistance in M. abscessus . The findings of this study will hopefully contribute to our knowledge of potential tigecycline resistance mechanisms in M. abscessus , which may lead to better diagnostics and treatment modalities in the future.
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- 2021
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23. 25S rDNA genotyping and multi-locus sequence typing of Candida albicans of pathogenic and commensal origins in the Klang Valley, Malaysia.
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Illyaaseen Z, Ngeow YF, Yap SF, and Ng HF
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- DNA, Ribosomal, Genotype, Humans, Malaysia, Multilocus Sequence Typing, Candida albicans genetics, Candidiasis
- Abstract
Candida albicans is an important opportunistic fungal pathogen capable of causing fatal systemic infections in humans. Presently in Malaysia, there is little information available on the genetic diversity of this organism and trends in behavioural characteristics. In this project, three genotyping methods: 25S rDNA genotyping, Alternative Lengthening of Telomerase (ALT) sequence typing and Multi-Locus Sequence Typing (MLST) were applied to study the genetic diversity of strains from infected hospital in-patients and asymptomatic individuals in the community. The results showed that, with the 25S rDNA genotyping, as in other parts of the world, the most common genotype was type A which accounted for approximately 70% of the 111 isolates tested. Further typing with the ALT sequence showed type 3 to be the most common in the isolates tested. MLST analysis revealed many possibly novel sequence types, as well as a statistically significant association between pathogenicity and a group of closely related isolates, most of which were from hospital samples. Further work on genotypes associated with enhanced virulence will help to clarify the value of genotyping for clinical and epidemiological investigations.
- Published
- 2021
24. COVID-19 in People Living with HIV: A Systematic Review and Meta-Analysis.
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Lee KW, Yap SF, Ngeow YF, and Lye MS
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- Fever, Humans, Pandemics, SARS-CoV-2, COVID-19, HIV Infections drug therapy, HIV Infections epidemiology
- Abstract
COVID-19 is a global health emergency. People living with human immunodeficiency virus (PLHIV) have concerns about whether they have a higher risk of getting the infection and suffer worse COVID-19 outcomes. Findings from studies on these questions have largely been inconsistent. We aimed to determine the epidemiological characteristics, clinical signs and symptoms, blood parameters, and clinical outcomes among PLHIV who contracted COVID-19. Relevant studies were identified through Medline, Cinahl, and PubMed databases. A random-effects model was used in meta-analyses with a 95% confidence interval. Eighty-two studies were included in the systematic review and sixty-seven studies for the meta-analysis. The pooled incidence proportion of COVID-19 among PLHIV was 0.9% (95% CI 0.6%, 1.1%) based on the data from seven cohort studies. Overall, 28.4% were hospitalised, of whom, 2.5% was severe-critical cases and 3.5% needed intensive care. The overall mortality rate was 5.3%. Hypertension was the most commonly reported comorbidity (24.0%). Fever (71.1%) was the most common symptom. Chest imaging demonstrated a wide range of abnormal findings encompassing common changes such as ground glass opacities and consolidation as well as a spectrum of less common abnormalities. Laboratory testing of inflammation markers showed that C-reactive protein, ferritin, and interleukin-6 were frequently elevated, albeit to different extents. Clinical features as well as the results of chest imaging and laboratory testing were similar in highly active antiretroviral therapy (HAART)-treated and non-treated patients. PLHIV were not found to be at higher risk for adverse outcomes of COVID-19. Hence, in COVID-19 management, it appears that they can be treated the same way as HIV negative individuals. Nevertheless, as the pandemic situation is rapidly evolving, more evidence may be needed to arrive at definitive recommendations.
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- 2021
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25. Colon Carcinogenesis: The Interplay Between Diet and Gut Microbiota.
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Loke YL, Chew MT, Ngeow YF, Lim WWD, and Peh SC
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- Animals, Carcinogenesis, Diet, Humans, Colorectal Neoplasms etiology, Gastrointestinal Microbiome
- Abstract
Colorectal cancer (CRC) incidence increases yearly, and is three to four times higher in developed countries compared to developing countries. The well-known risk factors have been attributed to low physical activity, overweight, obesity, dietary consumption including excessive consumption of red processed meats, alcohol, and low dietary fiber content. There is growing evidence of the interplay between diet and gut microbiota in CRC carcinogenesis. Although there appears to be a direct causal role for gut microbes in the development of CRC in some animal models, the link between diet, gut microbes, and colonic carcinogenesis has been established largely as an association rather than as a cause-and-effect relationship. This is especially true for human studies. As essential dietary factors influence CRC risk, the role of proteins, carbohydrates, fat, and their end products are considered as part of the interplay between diet and gut microbiota. The underlying molecular mechanisms of colon carcinogenesis mediated by gut microbiota are also discussed. Human biological responses such as inflammation, oxidative stress, deoxyribonucleic acid (DNA) damage can all influence dysbiosis and consequently CRC carcinogenesis. Dysbiosis could add to CRC risk by shifting the effect of dietary components toward promoting a colonic neoplasm together with interacting with gut microbiota. It follows that dietary intervention and gut microbiota modulation may play a vital role in reducing CRC risk., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Loke, Chew, Ngeow, Lim and Peh.)
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- 2020
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26. A single-gene approach for the subspecies classification of Mycobacteroides abscessus.
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Ng HF and Ngeow YF
- Subjects
- Bacterial Proteins genetics, DNA, Bacterial, Genes, Essential, Phylogeny, Polymerase Chain Reaction, Sequence Analysis, DNA, Bacterial Typing Techniques methods, Mycobacterium abscessus classification, Mycobacterium abscessus genetics, Phosphogluconate Dehydrogenase genetics
- Abstract
The subspecies classification of Mycobacteroides abscessus complex into M. abscessus, M. massiliense and M. bolletii requires the amplification and sequencing of multiple genes. The objective of this study was to evaluate the possibility of subspecies classification using a single PCR target. An in silico study was performed to classify 1613 strains deposited in a public database using 9 genes (partial gene sequences of hsp65, rpoB, sodA, argH, cya, glpK, gnd, and murC, and the full gene sequence of MAB_3542c). We found the housekeeping gene gnd to be able to classify the M. abscessus subspecies with high accuracy (99.94%). A single-gene PCR approach based on gnd would be a suitable replacement for the more expensive, labor-intensive and time-consuming multi-gene PCR analysis currently in use for the subspecies identification of M. abscessus., (© The Author(s) 2020. Published by Oxford University Press on behalf of FEMS.)
- Published
- 2020
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27. Genome sequence analysis of multidrug-resistant Mycobacterium tuberculosis from Malaysia.
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Tan JL, Simbun A, Chan KG, and Ngeow YF
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- Gene Transfer, Horizontal, Humans, Malaysia, Molecular Sequence Annotation, Mutation, Mycobacterium tuberculosis genetics, Tuberculosis, Multidrug-Resistant microbiology
- Abstract
Mycobacterium tuberculosis (MTB) is commonly used as a model to study pathogenicity and multiple drug resistance in bacteria. These MTB characteristics are highly dependent on the evolution and phylogeography of the bacterium. In this paper, we describe 15 new genomes of multidrug-resistant MTB (MDRTB) from Malaysia. The assessments and annotations on the genome assemblies suggest that strain differences are due to lineages and horizontal gene transfer during the course of evolution. The genomes show mutations listed in current drug resistance databases and global MTB collections. This genome data will augment existing information available for comparative genomic studies to understand MTB drug resistance mechanisms and evolution.
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- 2020
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28. Tigecycline resistance may be associated with dysregulated response to stress in Mycobacterium abscessus.
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Ng HF, Ngeow YF, Yap SF, Zin T, and Tan JL
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- Bacterial Proteins genetics, Gene Expression Regulation, Bacterial, Mycobacterium abscessus genetics, Ribosomal Proteins genetics, Sigma Factor genetics, Sigma Factor metabolism, Temperature, Transcription, Genetic, Anti-Bacterial Agents pharmacology, Drug Resistance, Bacterial genetics, Mycobacterium abscessus drug effects, Stress, Physiological, Tigecycline pharmacology
- Abstract
Previously, we characterized 7C, a laboratory-derived tigecycline-resistant mutant of Mycobacterium abscessus ATCC 19977, and found that the resistance was conferred by a mutation in MAB_3542c, which encodes an RshA-like protein. In M. tuberculosis, RshA is an anti-sigma factor that negatively regulates the SigH-dependent heat/oxidative stress response. We hypothesized that this mutation in 7C might dysregulate the stress response which has been generally linked to antibiotic resistance. In this study, we tested this hypothesis by subjecting 7C to transcriptomic dissection using RNA sequencing. We found an over-expression of genes encoding the SigH ortholog, chaperones and oxidoreductases. In line with these findings, 7C demonstrated better survival against heat shock when compared to the wild-type ATCC 19977. Another interesting observation from the RNA-Seq analysis was the down-regulation of ribosomal protein-encoding genes. This highlights the possibility of ribosomal conformation changes which could negatively affect the binding of tigecycline to its target, leading to phenotypic resistance. We also demonstrated that transient resistance to tigecycline could be induced in the ATCC 19977 by elevated temperature. Taken together, these findings suggest that dysregulated stress response may be associated with tigecycline resistance in M. abscessus., (Copyright © 2019 Elsevier GmbH. All rights reserved.)
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- 2020
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29. Increased Coffee Intake Reduces Circulating HBV DNA and HBsAg Levels in HBeAg-Negative Infection: A Cohort Study.
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Chook JB, Ngeow YF, Tee KK, Lee JWT, and Mohamed R
- Subjects
- Aged, Alanine Transaminase blood, Cohort Studies, Female, Hepatitis B virus genetics, Hepatitis B virus immunology, Hepatitis B, Chronic blood, Hepatitis B, Chronic epidemiology, Humans, Malaysia epidemiology, Male, Middle Aged, Viral Load, Coffee, DNA, Viral blood, Drinking Behavior, Hepatitis B Surface Antigens blood, Hepatitis B, Chronic virology
- Abstract
Coffee is hepatoprotective and potentially antiviral; however, its anti-hepatitis B virus (anti-HBV) property is not known in humans. This study investigated the influence of coffee drinking behaviour as well as clinical and biochemical profiles of hepatitis B e antigen (HBeAg) negative participants on circulating HBV DNA and hepatitis B surface antigen (HBsAg) levels at a 24-week interval. Exactly 114 chronically HBV-infected adult participants were enrolled from the University of Malaya Medical Centre (UMMC), Malaysia. A significant reduction of HBV DNA level was observed in those drinking three or more cups of coffee per day, with a median reduction of 523 IU/mL ( P = 0.003). Reduction of HBsAg level was observed in those drinking two cups per day, with a median reduction of 37 IU/mL ( P < 0.001). Multivariate analysis showed that increased coffee intake ( P = 0.015) and lower ALT level ( P = 0.033) were the significant predictors for a lower HBV DNA level, whereas increased coffee intake ( P = 0.002) and having a family history of HBV infection ( P = 0.021) were the significant predictors for a lower HBsAg level. These data suggest that drinking three cups or more coffee per day reduces circulating HBV DNA and HBsAg levels.
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- 2019
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30. A mutation in anti-sigma factor MAB_3542c may be responsible for tigecycline resistance in Mycobacterium abscessus.
- Author
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Ng HF, Tan JL, Zin T, Yap SF, and Ngeow YF
- Subjects
- Bacterial Proteins genetics, Gene Expression Regulation, Bacterial, Genome, Bacterial, Microbial Sensitivity Tests, Mutation, Anti-Bacterial Agents pharmacology, Bacterial Proteins metabolism, Drug Resistance, Bacterial, Mycobacterium abscessus drug effects, Mycobacterium abscessus genetics, Tigecycline pharmacology
- Abstract
In this study, we characterized 7C, a spontaneous mutant selected from tigecycline-susceptible Mycobacterium abscessus ATCC 19977. Whole-genome sequencing (WGS) was used to identify possible resistance determinants in this mutant. Compared to the wild-type, 7C demonstrated resistance to tigecycline as well as cross-resistance to imipenem, and had a slightly retarded growth rate. WGS and subsequent biological verifications showed that these phenotypes were caused by a point mutation in MAB_3542c, which encodes an RshA-like protein. In Mycobacterium tuberculosis, RshA is an anti-sigma factor that negatively regulates the heat/oxidative stress response mechanisms. The MAB_3542c mutation may represent a novel determinant of tigecycline resistance. We hypothesize that this mutation may dysregulate the stress-response pathways which have been shown to be linked to antibiotic resistance in previous studies.
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- 2018
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31. Phylogeny and putative virulence gene analysis of Bartonella bovis.
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Tay ST, Kho KL, Lye SF, and Ngeow YF
- Subjects
- Bacterial Proteins genetics, Bacterial Proteins metabolism, Base Sequence, DNA, Bacterial genetics, Gene Expression Regulation, Bacterial physiology, Sequence Analysis, DNA, Virulence, Bartonella genetics, Bartonella pathogenicity, Phylogeny, Virulence Factors genetics
- Abstract
Bartonella bovis is a small Gram-negative bacterium recognized as an etiological agent for bacteremia and endocarditis in cattle. As few reports are available on the taxonomic position of B. bovis and its mechanism of virulence, this study aims to resolve the phylogeny of B. bovis and investigate putative virulence genes based on whole genome sequence analysis. Genome-wide comparisons based on single nucleotide polymorphisms (SNP) and orthologous genes were performed in this study for phylogenetic inference of 27 Bartonella species. Rapid Annotation using Subsystem Technology (RAST) analysis was used for annotation of putative virulence genes. The phylogenetic tree generated from the genome-wide comparison of orthologous genes exhibited a topology almost similar to that of the tree generated from SNP-based comparison, indicating a high concordance in the nucleotide and amino acid sequences of Bartonella spp. The analyses show consistent grouping of B. bovis in a cluster related to ruminant-associated species, including Bartonella australis, Bartonella melophagi and Bartonella schoenbuchensis. RAST analysis revealed genes encoding flagellar components, in corroboration with the observation of flagella-like structure of BbUM strain under negative straining. Genes associated with virulence, disease and defence, prophages, membrane transport, iron acquisition, motility and chemotaxis are annotated in B. bovis genome. The flagellin (flaA) gene of B. bovis is closely related to Bartonella bacilliformis and Bartonella clarridgeiae but distinct from other Gram-negative bacteria. The absence of type IV secretion systems, the bona fide pathogenicity factors of bartonellae, in B. bovis suggests that it may have a different mechanism of pathogenicity.
- Published
- 2018
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32. Genomic Comparisons Reveal Microevolutionary Differences in Mycobacterium abscessus Subspecies.
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Tan JL, Ng KP, Ong CS, and Ngeow YF
- Abstract
Mycobacterium abscessus , a rapid-growing non-tuberculous mycobacterium, has been the cause of sporadic and outbreak infections world-wide. The subspecies in M. abscessus complex ( M. abscessus, M. massiliense , and M. bolletii ) are associated with different biologic and pathogenic characteristics and are known to be among the most frequently isolated opportunistic pathogens from clinical material. To date, the evolutionary forces that could have contributed to these biological and clinical differences are still unclear. We compared genome data from 243 M. abscessus strains downloaded from the NCBI ftp Refseq database to understand how the microevolutionary processes of homologous recombination and positive selection influenced the diversification of the M. abscessus complex at the subspecies level. The three subspecies are clearly separated in the Minimum Spanning Tree. Their MUMi-based genomic distances support the separation of M. massiliense and M. bolletii into two subspecies. Maximum Likelihood analysis through dN/dS (the ratio of number of non-synonymous substitutions per non-synonymous site, to the number of synonymous substitutions per synonymous site) identified distinct genes in each subspecies that could have been affected by positive selection during evolution. The results of genome-wide alignment based on concatenated locally-collinear blocks suggest that (a) recombination has affected the M. abscessus complex more than mutation and positive selection; (b) recombination occurred more frequently in M. massiliense than in the other two subspecies; and (c) the recombined segments in the three subspecies have come from different intra-species and inter-species origins. The results lead to the identification of possible gene sets that could have been responsible for the subspecies-specific features and suggest independent evolution among the three subspecies, with recombination playing a more significant role than positive selection in the diversification among members in this complex.
- Published
- 2017
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33. Antibiotic resistance in Mycobacterium Abscessus and Mycobacterium Fortuitum isolates from Malaysian patients.
- Author
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Jayasingam SD, Zin T, and Ngeow YF
- Subjects
- Drug Therapy, Combination standards, Humans, Malaysia, Microbial Sensitivity Tests, Microbial Viability drug effects, Mycobacterium Infections, Nontuberculous microbiology, Nontuberculous Mycobacteria isolation & purification, Nontuberculous Mycobacteria physiology, Anti-Bacterial Agents pharmacology, Anti-Bacterial Agents therapeutic use, Drug Resistance, Bacterial, Mycobacterium Infections, Nontuberculous drug therapy, Nontuberculous Mycobacteria drug effects
- Abstract
Background: Rapidly growing mycobacterial species (RGM) are increasingly being recognized as the cause of various superficial and deep infections in humans. Two of the species most frequently isolated from clinical specimens are Mycobacterium abscessus and Mycobacterium fortuitum. Both species are associated with antibiotic resistances that may complicate therapy. This paper describes the pattern of resistance to five antibiotics commonly prescribed for RGM infections, in M. abscessus and M. fortuitum isolated from Malaysian patients., Methods: The bacterial strains studied were examined with Etest strips to determine their minimum inhibitory concentrations (MICs) toward amikacin, ciprofloxacin, clarithromycin, imipenem, and linezolid., Results: Among 51 M. abscessus isolates examined by the Etest, the overall MICs of ciprofloxacin, imipenem, amikacin, clarithromycin, and linezolid showed resistance rates of 33.3%, 31.4%, 2.0%, 5.9%, and 21.6%, to the five antibiotics, respectively. M. abscessus subspecies abscessus was more resistant than M. abscessus subsp. massilience to ciprofloxacin, imipenem, and linezolid but was more susceptible to clarithromycin and amikacin. M. fortuitum isolates were significantly less resistant than M. abscessus to ciprofloxacin (3.6%) and imipenem (7.1%) but more resistant to clarithromycin (42.9%) and linezolid (39.3%)., Conclusion: A suitable combination therapy for Malaysian patients would be amikacin plus clarithromycin and ciprofloxacin, to cover infections by all three M. abscessus subspecies and M. fortuitum.
- Published
- 2017
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34. Synthesis of 2,4-Diaminopyrimidine Core-Based Derivatives and Biological Evaluation of Their Anti-Tubercular Activities.
- Author
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Ouyang Y, Yang H, Zhang P, Wang Y, Kaur S, Zhu X, Wang Z, Sun Y, Hong W, Ngeow YF, and Wang H
- Subjects
- Antitubercular Agents pharmacology, Hydrophobic and Hydrophilic Interactions, Microbial Sensitivity Tests, Mycobacterium tuberculosis drug effects, Structure-Activity Relationship, Antitubercular Agents chemical synthesis, Antitubercular Agents chemistry, Pyrimidines chemistry
- Abstract
Tuberculosis (TB) is a chronic, potentially fatal disease caused by Mycobacterium tuberculosis ( Mtb ). The dihyrofolate reductase in Mtb ( mt -DHFR) is believed to be an important drug target in anti-TB drug development. This enzyme contains a glycerol (GOL) binding site, which is assumed to be a useful site to improve the selectivity towards human dihyrofolate reductase ( h -DHFR). There have been previous attempts to design drugs targeting the GOL binding site, but the designed compounds contain a hydrophilic group, which may prevent the compounds from crossing the cell wall of Mtb to function at the whole cell level. In the current study, we designed and synthesized a series of mt -DHFR inhibitors that contain a 2,4-diaminopyrimidine core with side chains to occupy the glycerol binding site with proper hydrophilicity for cell entry, and tested their anti-tubercular activity against Mtb H37Ra. Among them, compound 16l showed a good anti-TB activity (MIC = 6.25 μg/mL) with a significant selectivity against vero cells. In the molecular simulations performed to understand the binding poses of the compounds, it was noticed that only side chains of a certain size can occupy the glycerol binding site. In summary, the novel synthesized compounds with appropriate side chains, hydrophobicity and selectivity could be important lead compounds for future optimization towards the development of future anti-TB drugs that can be used as monotherapy or in combination with other anti-TB drugs or antibiotics. These compounds can also provide much information for further studies on mt -DHFR. However, the enzyme target of the compounds still needs to be confirmed by pure mt -DHFR binding assays., Competing Interests: All authors declare no conflict of interest.
- Published
- 2017
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35. Synthesis and biological evaluation of indole core-based derivatives with potent antibacterial activity against resistant bacterial pathogens.
- Author
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Hong W, Li J, Chang Z, Tan X, Yang H, Ouyang Y, Yang Y, Kaur S, Paterson IC, Ngeow YF, and Wang H
- Subjects
- Anti-Bacterial Agents chemical synthesis, Anti-Bacterial Agents chemistry, Drug Design, Drug Resistance, Multiple, Bacterial, Indoles chemical synthesis, Indoles chemistry, Models, Molecular, Anti-Bacterial Agents pharmacology, Gram-Negative Bacteria drug effects, Gram-Positive Bacteria drug effects, Indoles pharmacology
- Abstract
The emergence of drug resistance in bacterial pathogens is a growing clinical problem that poses difficult challenges in patient management. To exacerbate this problem, there is currently a serious lack of antibacterial agents that are designed to target extremely drug-resistant bacterial strains. Here we describe the design, synthesis and antibacterial testing of a series of 40 novel indole core derivatives, which are predicated by molecular modeling to be potential glycosyltransferase inhibitors. Twenty of these derivatives were found to show in vitro inhibition of Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus. Four of these strains showed additional activity against Gram-negative bacteria, including extended-spectrum beta-lactamase producing Enterobacteriaceae, imipenem-resistant Klebsiella pneumoniae and multidrug-resistant Acinetobacter baumanii, and against Mycobacterium tuberculosis H37Ra. These four compounds are candidates for developing into broad-spectrum anti-infective agents.
- Published
- 2017
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36. Complete genome sequencing revealed novel genetic contexts of the mcr-1 gene in Escherichia coli strains.
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Yu CY, Ang GY, Chong TM, Chin PS, Ngeow YF, Yin WF, and Chan KG
- Subjects
- Whole Genome Sequencing methods, Escherichia coli genetics, Escherichia coli Proteins genetics, Genome, Bacterial genetics
- Published
- 2017
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37. Novel Genetic Variants of Hepatitis B Virus in Fulminant Hepatitis.
- Author
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Chook JB, Ngeow YF, Tee KK, Peh SC, and Mohamed R
- Abstract
Fulminant hepatitis (FH) is a life-threatening liver disease characterised by intense immune attack and massive liver cell death. The common precore stop codon mutation of hepatitis B virus (HBV), A1896, is frequently associated with FH, but lacks specificity. This study attempts to uncover all possible viral nucleotides that are specifically associated with FH through a compiled sequence analysis of FH and non-FH cases from acute infection. We retrieved 67 FH and 280 acute non-FH cases of hepatitis B from GenBank and applied support vector machine (SVM) model to seek candidate nucleotides highly predictive of FH. Six best candidates with top predictive accuracy, 92.5%, were used to build a SVM model; they are C2129 (85.3%), T720 (83.0%), Y2131 (82.4%), T2013 (82.1%), K2048 (82.1%), and A2512 (82.1%). This model gave a high specificity (99.3%), positive predictive value (95.6%), and negative predictive value (92.1%), but only moderate sensitivity (64.2%). We successfully built a SVM model comprising six variants that are highly predictive and specific for FH: four in the core region and one each in the polymerase and the surface regions. These variants indicate that intracellular virion/core retention could play an important role in the progression to FH.
- Published
- 2017
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38. Genome Sequences of Two Multidrug-Resistant Proteus mirabilis Strains Harboring CTX-M-65 Isolated from Malaysia.
- Author
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Yu CY, Ang GY, Ngeow YF, Tee KK, Yin WF, and Chan KG
- Abstract
Proteus mirabilis is an opportunistic nosocomial pathogen that is commonly associated with urinary tract infections. Here, we present draft genome sequences of two multidrug-resistant P. mirabilis strains, isolated from urine samples in Malaysia, that harbored a CTX-M-type extended-spectrum β-lactamase-encoding gene, as well as a repertoire of other antimicrobial-resistant determinants., (Copyright © 2016 Yu et al.)
- Published
- 2016
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39. Chromosomal rearrangements and protein globularity changes in Mycobacterium tuberculosis isolates from cerebrospinal fluid.
- Author
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Saw SH, Tan JL, Chan XY, Chan KG, and Ngeow YF
- Abstract
Background: Meningitis is a major cause of mortality in tuberculosis (TB). It is not clear what factors promote central nervous system invasion and pathology but it has been reported that certain strains of Mycobacterium tuberculosis (Mtb) might have genetic traits associated with neurotropism., Methods: In this study, we generated whole genome sequences of eight clinical strains of Mtb that were isolated from the cerebrospinal fluid (CSF) of patients presenting with tuberculous meningitis (TBM) in Malaysia, and compared them to the genomes of H37Rv and other respiratory Mtb genomes either downloaded from public databases or extracted from local sputum isolates. We aimed to find genomic features that might be distinctly different between CSF-derived and respiratory Mtb., Results: Genome-wide comparisons revealed rearrangements (translocations, inversions, insertions and deletions) and non-synonymous SNPs in our CSF-derived strains that were not observed in the respiratory Mtb genomes used for comparison. These rearranged segments were rich in genes for PE (proline-glutamate)/PPE (proline-proline-glutamate), transcriptional and membrane proteins. Similarly, most of the ns SNPs common in CSF strains were noted in genes encoding PE/PPE proteins. Protein globularity differences were observed among mycobacteria from CSF and respiratory sources and in proteins previously reported to be associated with TB meningitis. Transcription factors and other transcription regulators featured prominently in these proteins. Homologs of proteins associated with Streptococcus pneumoniae meningitis and Neisseria meningitidis virulence were identified in neuropathogenic as well as respiratory mycobacterial spp. examined in this study., Discussion: The occurrence of in silico genetic differences in CSF-derived but not respiratory Mtb suggests their possible involvement in the pathogenesis of TBM. However, overall findings in this comparative analysis support the postulation that TB meningeal infection is more likely to be related to the expression of multiple virulence factors on interaction with host defences than to CNS tropism associated with specific genetic traits., Competing Interests: The authors declare that they have no competing interests.
- Published
- 2016
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40. Emergence of mcr-1-mediated colistin resistance in Escherichia coli in Malaysia.
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Yu CY, Ang GY, Chin PS, Ngeow YF, Yin WF, and Chan KG
- Subjects
- Animals, Escherichia coli genetics, Escherichia coli isolation & purification, Genotype, Humans, Malaysia, Anti-Bacterial Agents pharmacology, Colistin pharmacology, Drug Resistance, Bacterial, Escherichia coli drug effects, Escherichia coli Infections microbiology, Escherichia coli Infections veterinary, Escherichia coli Proteins genetics
- Published
- 2016
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41. Insight into different environmental niches adaptation and allergenicity from the Cladosporium sphaerospermum genome, a common human allergy-eliciting Dothideomycetes.
- Author
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Yew SM, Chan CL, Ngeow YF, Toh YF, Na SL, Lee KW, Hoh CC, Yee WY, Ng KP, and Kuan CS
- Subjects
- Adaptation, Physiological, Allergens immunology, Aspergillus genetics, Aspergillus immunology, Cladosporium classification, Cladosporium immunology, Fungal Proteins immunology, Gene Expression, Gene Ontology, Humans, Hypersensitivity genetics, Hypersensitivity microbiology, Lung immunology, Lung microbiology, Melanins genetics, Melanins immunology, Molecular Sequence Annotation, Mycoses immunology, Mycoses microbiology, Peptide Hydrolases immunology, Phylogeny, Polyketides chemistry, Polyketides immunology, Siderophores chemistry, Siderophores immunology, Allergens genetics, Cladosporium genetics, Fungal Proteins genetics, Genome, Fungal, Hypersensitivity immunology, Peptide Hydrolases genetics
- Abstract
Cladosporium sphaerospermum, a dematiaceous saprophytic fungus commonly found in diverse environments, has been reported to cause allergy and other occasional diseases in humans. However, its basic biology and genetic information are largely unexplored. A clinical isolate C. sphaerospermum genome, UM 843, was re-sequenced and combined with previously generated sequences to form a model 26.89 Mb genome containing 9,652 predicted genes. Functional annotation on predicted genes suggests the ability of this fungus to degrade carbohydrate and protein complexes. Several putative peptidases responsible for lung tissue hydrolysis were identified. These genes shared high similarity with the Aspergillus peptidases. The UM 843 genome encodes a wide array of proteins involved in the biosynthesis of melanin, siderophores, cladosins and survival in high salinity environment. In addition, a total of 28 genes were predicted to be associated with allergy. Orthologous gene analysis together with 22 other Dothideomycetes showed genes uniquely present in UM 843 that encode four class 1 hydrophobins which may be allergens specific to Cladosporium. The mRNA of these hydrophobins were detected by RT-PCR. The genomic analysis of UM 843 contributes to the understanding of the biology and allergenicity of this widely-prevalent species.
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- 2016
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42. Evidence and potential risk factors of tuberculosis among captive Asian elephants and wildlife staff in Peninsular Malaysia.
- Author
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Yakubu Y, Ong BL, Zakaria Z, Hassan L, Mutalib AR, Ngeow YF, Verasahib K, and Razak MF
- Subjects
- Adult, Animals, Antibodies, Bacterial blood, Antigens, Bacterial blood, Cohort Studies, Cross-Sectional Studies, Female, Humans, Malaysia epidemiology, Male, Middle Aged, Prospective Studies, Risk Factors, Seroepidemiologic Studies, Tuberculosis microbiology, Young Adult, Elephants, Mycobacterium tuberculosis isolation & purification, Tuberculosis epidemiology, Tuberculosis veterinary
- Abstract
Elephant tuberculosis (TB) caused by Mycobacterium tuberculosis is an important re-emerging zoonosis with considerable conservation and public health risk. We conducted prospective cohort and cross-sectional studies in elephants and wildlife staff respectively in order to identify potential risk factors associated with TB in captive Asian elephants and their handlers in Peninsular Malaysia. Sixty elephants in six different facilities were screened for TB longitudinally using the ElephantTB STAT-PAK and DPP VetTB assays from February 2012 to May 2014, and 149 wildlife staff were examined for tuberculosis infection using the QuantiFERON-TB Gold In-tube (QFT) assay from January to April, 2012. Information on potential risk factors associated with infection in both elephants and staff were collected using questionnaires and facility records. The overall seroprevalence of TB amongst the elephants was 23.3% (95% CI: 13.8-36.3) and the risk of seroconversion was significantly higher among elephants with assigned mahouts [p=0.022, OR=4.9 (95% CI: 1.3-18.2)]. The percentage of QFT responders among wildlife staff was 24.8% (95% CI: 18.3-32.7) and the risk of infection was observed to be significantly associated with being a zoo employee [p=0.018, OR=2.7 (95% CI: 1.2-6.3)] or elephant handler [p=0.035, OR=4.1 (95% CI: 1.1-15.5)]. These findings revealed a potential risk of TB infection in captive elephants and handlers in Malaysia, and emphasize the need for TB screening of newly acquired elephants, isolating sero-positive elephants and performing further diagnostic tests to determine their infection status, and screening elephant handlers for TB, pre- and post-employment., (Copyright © 2016 Elsevier B.V. All rights reserved.)
- Published
- 2016
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43. Genome-wide mosaicism within Mycobacterium abscessus: evolutionary and epidemiological implications.
- Author
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Sapriel G, Konjek J, Orgeur M, Bouri L, Frézal L, Roux AL, Dumas E, Brosch R, Bouchier C, Brisse S, Vandenbogaert M, Thiberge JM, Caro V, Ngeow YF, Tan JL, Herrmann JL, Gaillard JL, Heym B, and Wirth T
- Subjects
- Bacterial Typing Techniques, Comparative Genomic Hybridization, Conjugation, Genetic, DNA, Bacterial genetics, Gene Flow, Gene Frequency, Gene Transfer, Horizontal, Humans, Models, Genetic, Multilocus Sequence Typing, Phylogeny, Sequence Analysis, DNA, Evolution, Molecular, Genome, Bacterial, Mosaicism, Mycobacterium genetics
- Abstract
Background: In mycobacteria, conjugation differs from the canonical Hfr model, but is still poorly understood. Here, we quantified this evolutionary processe in a natural mycobacterial population, taking advantage of a large clinical strain collection of the emerging pathogen Mycobacterium abscessus (MAB)., Results: Multilocus sequence typing confirmed the existence of three M. abscessus subspecies, and unravelled extensive allelic exchange between them. Furthermore, an asymmetrical gene flow occurring between these main lineages was detected, resulting in highly admixed strains. Intriguingly, these mosaic strains were significantly associated with cystic fibrosis patients with lung infections or chronic colonization. Genome sequencing of those hybrid strains confirmed that half of their genomic content was remodelled in large genomic blocks, leading to original tri-modal 'patchwork' architecture. One of these hybrid strains acquired a locus conferring inducible macrolide resistance, and a large genomic insertion from a slowly growing pathogenic mycobacteria, suggesting an adaptive gene transfer. This atypical genomic architecture of the highly recombinogenic strains is consistent with the distributive conjugal transfer (DCT) observed in M. smegmatis. Intriguingly, no known DCT function was found in M. abscessus chromosome, however, a p-RAW-like genetic element was detected in one of the highly admixed strains., Conclusion: Taken together, our results strongly suggest that MAB evolution is sporadically punctuated by dramatic genome wide remodelling events. These findings might have far reaching epidemiological consequences for emerging mycobacterial pathogens survey in the context of increasing numbers of rapidly growing mycobacteria and M. tuberculosis co-infections.
- Published
- 2016
- Full Text
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44. The genome of newly classified Ochroconis mirabilis: Insights into fungal adaptation to different living conditions.
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Yew SM, Chan CL, Kuan CS, Toh YF, Ngeow YF, Na SL, Lee KW, Hoh CC, Yee WY, and Ng KP
- Subjects
- Ascomycota growth & development, Ascomycota metabolism, Carbohydrate Metabolism genetics, Computational Biology methods, DNA Transposable Elements, DNA, Intergenic, Genes, Fungal, Genomics, Mirabilis, Molecular Sequence Annotation, Multigene Family, Phenotype, Phylogeny, Secondary Metabolism, Adaptation, Biological genetics, Ascomycota classification, Ascomycota genetics, Genome, Fungal
- Abstract
Background: Ochroconis mirabilis, a recently introduced water-borne dematiaceous fungus, is occasionally isolated from human skin lesions and nails. We identified an isolate of O. mirabilis from a skin scraping with morphological and molecular studies. Its genome was then sequenced and analysed for genetic features related to classification and biological characteristics., Results: UM 578 was identified as O. mirabilis based on morphology and internal transcribed spacer (ITS)-based phylogeny. The 34.61 Mb assembled genome with 13,435 predicted genes showed less efficiency of this isolate in plant cell wall degradation. Results from the peptidase comparison analysis with reported keratin-degrading peptidases from dermatophytes suggest that UM 578 is very unlikely to be utilising these peptidases to survive in the host. Nevertheless, we have identified peptidases from M10A, M12A and S33 families that may allow UM 578 to invade its host via extracellular matrix and collagen degradation. Furthermore, the lipases in UM 578 may have a role in supporting the fungus in host invasion. This fungus has the potential ability to synthesise melanin via the 1,8-dihydroxynaphthalene (DHN)-melanin pathway and to produce mycotoxins. The mating ability of this fungus was also inspected in this study and a mating type gene containing alpha domain was identified. This fungus is likely to produce taurine that is required in osmoregulation. The expanded gene family encoding the taurine catabolism dioxygenase TauD/TdfA domain suggests the utilisation of taurine under sulfate starvation. The expanded glutathione-S-transferase domains and RTA1-like protein families indicate the selection of genes in UM 578 towards adaptation in hostile environments., Conclusions: The genomic analysis of O. mirabilis UM 578 provides a better understanding of fungal survival tactics in different habitats.
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- 2016
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45. Genome sequencing and annotation of multidrug resistant Mycobacterium tuberculosis (MDR-TB) PR10 strain.
- Author
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Halim MZ, Jaafar MM, Teh LK, Ismail MI, Lee LS, Ngeow YF, Nor NM, Zainuddin ZF, Tang TH, Najimudin MN, and Salleh MZ
- Abstract
Here, we report the draft genome sequence and annotation of a multidrug resistant Mycobacterium tuberculosis strain PR10 (MDR-TB PR10) isolated from a patient diagnosed with tuberculosis. The size of the draft genome MDR-TB PR10 is 4.34 Mbp with 65.6% of G + C content and consists of 4637 predicted genes. The determinants were categorized by RAST into 400 subsystems with 4286 coding sequences and 50 RNAs. The whole genome shotgun project has been deposited at DDBJ/EMBL/GenBank under the accession number CP010968.
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- 2016
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46. Genome analysis of Daldinia eschscholtzii strains UM 1400 and UM 1020, wood-decaying fungi isolated from human hosts.
- Author
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Chan CL, Yew SM, Ngeow YF, Na SL, Lee KW, Hoh CC, Yee WY, and Ng KP
- Subjects
- Adaptation, Physiological genetics, Cell Wall metabolism, Cell Wall microbiology, Fungal Proteins genetics, Fungal Proteins metabolism, Genes, Fungal genetics, Host-Pathogen Interactions, Humans, Peptide Hydrolases metabolism, Phylogeny, Signal Transduction genetics, Skin microbiology, Stress, Physiological genetics, Wood cytology, Xylariales cytology, Xylariales physiology, Genomics, Wood metabolism, Wood microbiology, Xylariales genetics, Xylariales metabolism
- Abstract
Background: Daldinia eschscholtzii is a wood-inhabiting fungus that causes wood decay under certain conditions. It has a broad host range and produces a large repertoire of potentially bioactive compounds. However, there is no extensive genome analysis on this fungal species., Results: Two fungal isolates (UM 1400 and UM 1020) from human specimens were identified as Daldinia eschscholtzii by morphological features and ITS-based phylogenetic analysis. Both genomes were similar in size with 10,822 predicted genes in UM 1400 (35.8 Mb) and 11,120 predicted genes in UM 1020 (35.5 Mb). A total of 751 gene families were shared among both UM isolates, including gene families associated with fungus-host interactions. In the CAZyme comparative analysis, both genomes were found to contain arrays of CAZyme related to plant cell wall degradation. Genes encoding secreted peptidases were found in the genomes, which encode for the peptidases involved in the degradation of structural proteins in plant cell wall. In addition, arrays of secondary metabolite backbone genes were identified in both genomes, indicating of their potential to produce bioactive secondary metabolites. Both genomes also contained an abundance of gene encoding signaling components, with three proposed MAPK cascades involved in cell wall integrity, osmoregulation, and mating/filamentation. Besides genomic evidence for degrading capability, both isolates also harbored an array of genes encoding stress response proteins that are potentially significant for adaptation to living in the hostile environments., Conclusions: Our genomic studies provide further information for the biological understanding of the D. eschscholtzii and suggest that these wood-decaying fungi are also equipped for adaptation to adverse environments in the human host.
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- 2015
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47. Multiphasic strain differentiation of atypical mycobacteria from elephant trunk wash.
- Author
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Chan KG, Loke MF, Ong BL, Wong YL, Hong KW, Tan KH, Kaur S, Ng HF, Abdul Razak M, and Ngeow YF
- Abstract
Background. Two non-tuberculous mycobacterial strains, UM_3 and UM_11, were isolated from the trunk wash of captive elephants in Malaysia. As they appeared to be identical phenotypes, they were investigated further by conventional and whole genome sequence-based methods of strain differentiation. Methods. Multiphasic investigations on the isolates included species identification with hsp65 PCR-sequencing, conventional biochemical tests, rapid biochemical profiling using API strips and the Biolog Phenotype Microarray analysis, protein profiling with liquid chromatography-mass spectrometry, repetitive sequence-based PCR typing and whole genome sequencing followed by phylogenomic analyses. Results. The isolates were shown to be possibly novel slow-growing schotochromogens with highly similar biological and genotypic characteristics. Both strains have a genome size of 5.2 Mbp, G+C content of 68.8%, one rRNA operon and 52 tRNAs each. They qualified for classification into the same species with their average nucleotide identity of 99.98% and tetranucleotide correlation coefficient of 0.99999. At the subspecies level, both strains showed 98.8% band similarity in the Diversilab automated repetitive sequence-based PCR typing system, 96.2% similarity in protein profiles obtained by liquid chromatography mass spectrometry, and a genomic distance that is close to zero in the phylogenomic tree constructed with conserved orthologs. Detailed epidemiological tracking revealed that the elephants shared a common habitat eight years apart, thus, strengthening the possibility of a clonal relationship between the two strains.
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- 2015
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48. Support from Phylogenomic Networks and Subspecies Signatures for Separation of Mycobacterium massiliense from Mycobacterium bolletii.
- Author
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Tan JL, Ngeow YF, and Choo SW
- Subjects
- Humans, Molecular Sequence Data, Nucleoside-Phosphate Kinase genetics, RNA, Ribosomal genetics, Ribosomal Proteins genetics, Sequence Alignment, Mycobacterium classification, Mycobacterium genetics, Phylogeny
- Abstract
Mycobacterium abscessus subspecies classification has important clinical implications. We used phylogenomic network and amino acid analyses to provide evidence for the separation of Mycobacterium bolletii and Mycobacterium massiliense into two distinct subspecies which can potentially be differentiated rapidly by their protein signatures., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)
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- 2015
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49. Genome Analysis of the First Extensively Drug-Resistant (XDR) Mycobacterium tuberculosis in Malaysia Provides Insights into the Genetic Basis of Its Biology and Drug Resistance.
- Author
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Kuan CS, Chan CL, Yew SM, Toh YF, Khoo JS, Chong J, Lee KW, Tan YC, Yee WY, Ngeow YF, and Ng KP
- Subjects
- Antitubercular Agents therapeutic use, Extensively Drug-Resistant Tuberculosis genetics, Gene Expression Profiling, Genome, Bacterial, Humans, Malaysia, Male, Microbial Sensitivity Tests, Middle Aged, Mycobacterium tuberculosis isolation & purification, Mycobacterium tuberculosis pathogenicity, Phylogeny, Polymorphism, Single Nucleotide, Drug Resistance, Multiple, Bacterial genetics, Extensively Drug-Resistant Tuberculosis microbiology, Mycobacterium tuberculosis genetics
- Abstract
The outbreak of extensively drug-resistant tuberculosis (XDR-TB) has become an increasing problem in many TB-burdened countries. The underlying drug resistance mechanisms, including the genetic variation favored by selective pressure in the resistant population, are partially understood. Recently, the first case of XDR-TB was reported in Malaysia. However, the detailed genotype family and mechanisms of the formation of multiple drugs resistance are unknown. We sequenced the whole genome of the UM 1072388579 strain with a 2-kb insert-size library and combined with that from previously sequenced 500-bp-insert paired-end reads to produce an improved sequence with maximal sequencing coverage across the genome. In silico spoligotyping and phylogenetic analyses demonstrated that UM 1072388579 strain belongs to an ancestral-like, non-Beijing clade of East Asia lineage. This is supported by the presence of a number of lineage-specific markers, including fadD28, embA, nuoD and pks7. Polymorphism analysis showed that the drug-susceptibility profile is correlated with the pattern of resistance mutations. Mutations in drug-efflux pumps and the cell wall biogenesis pathway such as mmpL, pks and fadD genes may play an important role in survival and adaptation of this strain to its surrounding environment. In this work, fifty-seven putative promoter SNPs were identified. Among them, we identified a novel SNP located at -4 T allele of TetR/acrR promoter as an informative marker to recognize strains of East Asian lineage. Our work indicates that the UM 1072388579 harbors both classical and uncommon SNPs that allow it to escape from inhibition by many antibiotics. This study provides a strong foundation to dissect the biology and underlying resistance mechanisms of the first reported XDR M. tuberculosis in Malaysia.
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- 2015
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50. The mRNA expression of soluble urokinase plasminogen activator surface receptor in human adipose tissue is positively correlated with body mass index.
- Author
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Ng HF, Chin KF, Chan KG, and Ngeow YF
- Subjects
- Adolescent, Adult, Cross-Sectional Studies, Humans, Mannose-Binding Lectins metabolism, Membrane Glycoproteins metabolism, Middle Aged, Obesity genetics, Obesity metabolism, Pilot Projects, RNA Splicing, RNA, Messenger metabolism, Receptors, Cell Surface metabolism, Reproducibility of Results, Sequence Analysis, RNA, Up-Regulation, Young Adult, Adipose Tissue metabolism, Body Mass Index, Mannose-Binding Lectins genetics, Membrane Glycoproteins genetics, RNA, Messenger genetics, Receptors, Cell Surface genetics
- Abstract
suPLAUR is the transcript variant that encodes the soluble form of the urokinase plasminogen activator surface receptor (suPLAUR). This soluble protein has been shown to enhance leukocyte migration and adhesion, and its circulatory level is increased in inflammatory states. In this pilot study, we used RNA-Seq to examine the splicing pattern of PLAUR in omental adipose tissues from obese and lean individuals. Of the three transcript variants of the PLAUR gene, only the proportion of suPLAUR (transcript variant 2) increases in obesity. After removing the effects of gender and age, the expression of suPLAUR is positively correlated with body mass index. This observation was validated using RT-qPCR with an independent cohort of samples. Additionally, in our RNA-Seq differential expression analysis, we also observed, in obese adipose tissues, an up-regulation of genes encoding other proteins involved in the process of chemotaxis and leukocyte adhesion; of particular interest is the integrin beta 2 (ITGB2) that is known to interact with suPLAUR in leukocyte adhesion. These findings suggest an important role for suPLAUR in the recruitment of immune cells to obese adipose tissue, in the pathogenesis of obesity.
- Published
- 2015
- Full Text
- View/download PDF
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