23 results on '"Barkham, Timothy"'
Search Results
2. Structural insights into the interaction of antifungal peptides and ergosterol containing fungal membrane
- Author
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Mohid, Sk Abdul, Biswas, Karishma, Won, TaeJun, Mallela, Lakshmi S., Gucchait, Arin, Butzke, Lena, Sarkar, Riddhiman, Barkham, Timothy, Reif, Bernd, Leipold, Enrico, Roy, Sanhita, Misra, Anup K., Lakshminarayanan, Rajamani, Lee, DongKuk, and Bhunia, Anirban
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- 2022
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3. Sequence Types and Antimicrobial Resistance Profiles of Salmonella Typhimurium in the Food Chain in Singapore.
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Lim, Yen Ching, Ong, Kar Hui, Khor, Wei Ching, Chua, Favian Yue Xuan, Lim, Jia Qi, Tan, Li Kiang, Chen, Swaine L., Wong, Wai Kwan, Maiwald, Matthias, Barkham, Timothy, Koh, Tse Hsien, Khoo, Joanna, Chan, Joanne Sheot Harn, and Aung, Kyaw Thu
- Subjects
WHOLE genome sequencing ,SALMONELLA typhimurium ,DRUG resistance in microorganisms ,FOOD pathogens ,CHICKENS ,LACTAMS - Abstract
Salmonella remains a significant foodborne pathogen globally with S. Typhimurium presenting as a frequently occurring serovar. This study aimed to characterize 67 S. Typhimurium isolates from humans, food, farms, and slaughterhouses collected in Singapore from 2016 to 2017. Using whole-genome sequencing analysis, the isolates were found to belong to either ST19 (n = 33) or ST36 (n = 34). ST36 predominated in human intestinal and chicken isolates, while human extra-intestinal and non-chicken food isolates belonged to ST19. Plasmids were predicted in 88.1% (n = 59) of the isolates with the most common incompatibility group profiles being IncFIB(S), IncFII(S) and IncQ1. IncFIB(S) (adjusted p-value < 0.05) and IncFII(S) (adjusted p-value < 0.05) were significantly more prevalent in ST19 isolates, while Col156 (adjusted p-value < 0.05) was more significantly found in ST36 isolates. ST36 isolates exhibited higher resistance to multiple antibiotic classes such as penicillins, phenicols, folate pathway inhibitors, aminoglycosides, β-lactam/β-lactamase inhibitor combinations, tetracyclines, and fluoroquinolones. Phylogenetics analysis suggested potential shared routes of transmission among human, chicken, farm and slaughterhouse environments. Taken together, this study offers a cross-sectional epidemiological insight into the genomic epidemiology and antimicrobial landscape of S. Typhimurium isolates in Singapore, informing strategies for future public health and food safety surveillance. [ABSTRACT FROM AUTHOR]
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- 2024
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4. Human Fecal Carriage of Streptococcus agalactiae Sequence Type 283, Thailand
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Barkham, Timothy, primary, Tang, Wen Ying, additional, Wang, Yi-Chen, additional, Sithithaworn, Paiboon, additional, Kopolrat, Kulthida Y., additional, and Worasith, Chanika, additional
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- 2023
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5. Bacterial diseases of tilapia, their zoonotic potential and risk of antimicrobial resistance
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Haenen, Olga L. M., Ha, Thanh Dong, Truong, Dinh Hoai, Crumlish, Margaret, Karunasagar, Iddya, Barkham, Timothy, Chen, Swaine L., Zadoks, Ruth, Kiermeier, Andreas, Wang, Bing, Gamarro, Esther Garrido, Takeuchi, Masami, Azmai, Mohammad Noor Amal, Fouz, Belén, Pakingking Jr., Rolando, Zeng, Wei Wei, Bondad-Reantaso, Melba G., Haenen, Olga L. M., Ha, Thanh Dong, Truong, Dinh Hoai, Crumlish, Margaret, Karunasagar, Iddya, Barkham, Timothy, Chen, Swaine L., Zadoks, Ruth, Kiermeier, Andreas, Wang, Bing, Gamarro, Esther Garrido, Takeuchi, Masami, Azmai, Mohammad Noor Amal, Fouz, Belén, Pakingking Jr., Rolando, Zeng, Wei Wei, and Bondad-Reantaso, Melba G.
- Abstract
Tilapia culture is an important source of income and nutrition to many rural families. Since 2000, the production of tilapia increased and reached domestic and global markets. Major farmed species is Nile tilapia (Oreochromis niloticus), in earthen ponds and cage cultures. Intensification contributed to global tilapia disease outbreaks, with bacterial infections causing mortalities and morbidities, threatening sustainable production. At tilapia farms, high nutrient concentrations, water temperature and fish densities enhance bacterial growth including virulent bacterial clones and potential zoonotic bacteria. Global warming favours this. This review respectively provides a comprehensive overview of the most common and emerging bacterial pathogens, diseases, clinical presentations and diagnostics of tilapia, including bacteria and diseases with zoonotic potential. First, common bacterial disease outbreaks, including streptococcosis, motile Aeromonas septicaemia, francisellosis, columnaris disease and vibriosis are described. Then, information on emerging bacterial infections of concern for tilapia, like edwardsiellosis through Edwardsiella ictaluri and E. tarda, as well as Aeromonas schubertii is provided. Reports of infectious bacterial tilapia disease outbreaks from other bacteria, including Lactococcus garvieae, Aerococcus viridans, Pseudomonas spp., Mycobacterium marinum and Chlamydia spp., and others are reviewed. Furthermore, bacteria with zoonotic potential, like Streptococcus agalactiae ST283, S. iniae, Aeromonas sp., E. tarda, Vibrio vulnificus pathovar (pv) piscis and M. marinum are included in the review, to provide the most current overview of the disease risks affecting production and post-harvest stages. Additionally, the status and risks of antimicrobial resistance in bacteria from tilapia and other cultured fish through imprudent use of antibiotics, and its future at a global level are provided.
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- 2023
6. Bacterial diseases of tilapia, their zoonotic potential and risk of antimicrobial resistance
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Haenen, Olga L.M., Dong, Ha Thanh, Hoai, Truong Dinh, Crumlish, Margaret, Karunasagar, Iddya, Barkham, Timothy, Chen, Swaine L., Zadoks, Ruth, Kiermeier, Andreas, Wang, Bing, Gamarro, Esther Garrido, Takeuchi, Masami, Azmai, Mohammad Noor Amal, Fouz, Belén, Pakingking, Rolando, Wei, Zeng Wei, Bondad‐Reantaso, Melba G., Haenen, Olga L.M., Dong, Ha Thanh, Hoai, Truong Dinh, Crumlish, Margaret, Karunasagar, Iddya, Barkham, Timothy, Chen, Swaine L., Zadoks, Ruth, Kiermeier, Andreas, Wang, Bing, Gamarro, Esther Garrido, Takeuchi, Masami, Azmai, Mohammad Noor Amal, Fouz, Belén, Pakingking, Rolando, Wei, Zeng Wei, and Bondad‐Reantaso, Melba G.
- Abstract
Tilapia culture is an important source of income and nutrition to many rural families. Since 2000, the production of tilapia increased and reached domestic and global markets. Major farmed species is Nile tilapia (Oreochromis niloticus), in earthen ponds and cage cultures. Intensification contributed to global tilapia disease outbreaks, with bacterial infections causing mortalities and morbidities, threatening sustainable production. At tilapia farms, high nutrient concentrations, water temperature and fish densities enhance bacterial growth including virulent bacterial clones and potential zoonotic bacteria. Global warming favours this. This review respectively provides a comprehensive overview of the most common and emerging bacterial pathogens, diseases, clinical presentations and diagnostics of tilapia, including bacteria and diseases with zoonotic potential. First, common bacterial disease outbreaks, including streptococcosis, motile Aeromonas septicaemia, francisellosis, columnaris disease and vibriosis are described. Then, information on emerging bacterial infections of concern for tilapia, like edwardsiellosis through Edwardsiella ictaluri and E. tarda, as well as Aeromonas schubertii is provided. Reports of infectious bacterial tilapia disease outbreaks from other bacteria, including Lactococcus garvieae, Aerococcus viridans, Pseudomonas spp., Mycobacterium marinum and Chlamydia spp., and others are reviewed. Furthermore, bacteria with zoonotic potential, like Streptococcus agalactiae ST283, S. iniae, Aeromonas sp., E. tarda, Vibrio vulnificus pathovar (pv) piscis and M. marinum are included in the review, to provide the most current overview of the disease risks affecting production and post-harvest stages. Additionally, the status and risks of antimicrobial resistance in bacteria from tilapia and other cultured fish through imprudent use of antibiotics, and its future at a global level are provided.
- Published
- 2023
7. Bacterial diseases of tilapia, their zoonotic potential and risk of antimicrobial resistance
- Author
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Haenen, Olga, Thanh Dong, Ha, Hoai, Truong Dinh, Crumlish, Mags, Karunasagar, Iddya, Barkham, Timothy, Chen, Swaine, Zadoks, Ruth, Kiermeier, Andreas, Wang, Bing, Garrido Gamarro, Esther, Takeuchi, Masami, Amal, Mohammad Noor Azmai, Fouz, Belén, Pakingking, Rolando V., Jr., Zeng, Weiwei, Bondad-Reantaso, Melba, Haenen, Olga, Thanh Dong, Ha, Hoai, Truong Dinh, Crumlish, Mags, Karunasagar, Iddya, Barkham, Timothy, Chen, Swaine, Zadoks, Ruth, Kiermeier, Andreas, Wang, Bing, Garrido Gamarro, Esther, Takeuchi, Masami, Amal, Mohammad Noor Azmai, Fouz, Belén, Pakingking, Rolando V., Jr., Zeng, Weiwei, and Bondad-Reantaso, Melba
- Abstract
Tilapia culture is an important source of income and nutrition to many rural families. Since 2000, the production of tilapia increased and reached domestic and global markets. Major farmed species is Nile tilapia (Oreochromis niloticus), in earthen ponds and cage cultures. Intensification contributed to global tilapia disease outbreaks, with bacterial infections causing mortalities and morbidities, threatening sustainable production. At tilapia farms, high nutrient concentrations, water temperature and fish densities enhance bacterial growth including virulent bacterial clones and potential zoonotic bacteria. Global warming favours this. This review respectively provides a comprehensive overview of the most common and emerging bacterial pathogens, diseases, clinical presentations and diagnostics of tilapia, including bacteria and diseases with zoonotic potential. First, common bacterial disease outbreaks, including streptococcosis, motile Aeromonas septicaemia, francisellosis, columnaris disease and vibriosis are described. Then, information on emerging bacterial infections of concern for tilapia, like edwardsiellosis through Edwardsiella ictaluri and E. tarda, as well as Aeromonas schubertii is provided. Reports of infectious bacterial tilapia disease outbreaks from other bacteria, including Lactococcus garvieae, Aerococcus viridans, Pseudomonas spp., Mycobacterium marinum and Chlamydia spp., and others are reviewed. Furthermore, bacteria with zoonotic potential, like Streptococcus agalactiae ST283, S. iniae, Aeromonas sp., E. tarda, Vibrio vulnificus pathovar (pv) piscis and M. marinum are included in the review, to provide the most current overview of the disease risks affecting production and post-harvest stages. Additionally, the status and risks of antimicrobial resistance in bacteria from tilapia and other cultured fish t
- Published
- 2023
8. Bacterial diseases of tilapia, their zoonotic potential and risk of antimicrobial resistance
- Author
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Haenen, Olga L. M., primary, Dong, Ha Thanh, additional, Hoai, Truong Dinh, additional, Crumlish, Margaret, additional, Karunasagar, Iddya, additional, Barkham, Timothy, additional, Chen, Swaine L., additional, Zadoks, Ruth, additional, Kiermeier, Andreas, additional, Wang, Bing, additional, Gamarro, Esther Garrido, additional, Takeuchi, Masami, additional, Azmai, Mohammad Noor Amal, additional, Fouz, Belén, additional, Pakingking, Rolando, additional, Wei, Zeng Wei, additional, and Bondad‐Reantaso, Melba G., additional
- Published
- 2023
- Full Text
- View/download PDF
9. Molecular characterisation of a meropenem-resistant Haemophilus influenzae
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Chen, Yuan Yi Constance, primary, Tang, Wen Ying, additional, and Barkham, Timothy, additional
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- 2023
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10. Invasive Streptococcus agalactiae ST283 infection after fish consumption in two sisters, Lao PDR
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Luangraj, Manophab, primary, Hiestand, Jasmin, additional, Rasphone, Othila, additional, Chen, Swaine L., additional, Davong, Viengmon, additional, Barkham, Timothy, additional, Simpson, Andrew J.H., additional, Dance, David A.B., additional, and Keoluangkhot, Valy, additional
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- 2022
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11. Escherichia coli BarA-UvrY regulates the pks island and kills Staphylococci via the genotoxin colibactin during interspecies competition
- Author
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Wong, Jun Jie, primary, Ho, Foo Kiong, additional, Choo, Pei Yi, additional, Chong, Kelvin K. L., additional, Ho, Chee Meng Benjamin, additional, Neelakandan, Ramesh, additional, Keogh, Damien, additional, Barkham, Timothy, additional, Chen, John, additional, Liu, Chuan Fa, additional, and Kline, Kimberly A., additional
- Published
- 2022
- Full Text
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12. Characterisation of Salmonella enteritidis ST11 and ST1925 Associated with Human Intestinal and Extra-Intestinal Infections in Singapore
- Author
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Aung, Kyaw Thu, Khor, Wei Ching, Ong, Kar Hui, Tan, Wei Ling, Wong, Zhi Ning, Oh, Jia Quan, Wong, Wai Kwan, Tan, Brian Zi Yan, Maiwald, Matthias, Tee, Nancy Wen Sim, Barkham, Timothy, Koh, Tse Hsien, Dalsgaard, Anders, Chen, Swaine L., Schlundt, Joergen, Ng, Lee Ching, Aung, Kyaw Thu, Khor, Wei Ching, Ong, Kar Hui, Tan, Wei Ling, Wong, Zhi Ning, Oh, Jia Quan, Wong, Wai Kwan, Tan, Brian Zi Yan, Maiwald, Matthias, Tee, Nancy Wen Sim, Barkham, Timothy, Koh, Tse Hsien, Dalsgaard, Anders, Chen, Swaine L., Schlundt, Joergen, and Ng, Lee Ching
- Abstract
Salmonella enteritidis is a major foodborne pathogen worldwide. In this study, a total of 276 S. enteritidis isolates, collected between 2016 and 2017 from human, food and farm/slaughterhouse samples, were studied to enhance the understanding of the epidemiology of human salmonellosis in Singapore. Results showed all 276 isolates belonged either to ST1925 (70.3%) or ST11 (29.7%), with ST11 being significantly more frequent in extra-intestinal isolates and chicken isolates. Food isolates, most of which were from poultry, showed the highest prevalence of resistance (33–37%) against beta-lactams or beta-lactams/beta-lactamase inhibitor combination (ampicillin, piperacillin and ampicillin/sulbactam). The analysis showed the detection of genes associated with resistance to aminoglycoside genes (99.6%), tetracycline (55.1%), and beta-lactams (14.9%) of all isolates. Nine types of plasmids were found in 266 isolates; the most common incompatibility group profiles were IncFIB(S)-IncFII(S)-IncX1 (72.2%) and IncFIB(S)-IncFII(S) (15.8%). Most plasmid harbouring isolates from chicken (63.6%, 14/22) and from human (73.8%, 175/237) shared the same plasmid profile (IncFIB(S)-IncFII(S)-IncX1). SNP analysis showed clustering of several isolates from poultry food products and human isolates, suggesting phylogenetic relatedness among these isolates. Lastly, this study provides important epidemiological insights on the application of phenotypic and next-generation sequencing (NGS) tools for improved food safety and public health surveillance and outbreak investigation of S. enteritidis.
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- 2022
13. Characterisation of Salmonella Enteritidis ST11 and ST1925 Associated with Human Intestinal and Extra-Intestinal Infections in Singapore
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Aung, Kyaw Thu, primary, Khor, Wei Ching, additional, Ong, Kar Hui, additional, Tan, Wei Ling, additional, Wong, Zhi Ning, additional, Oh, Jia Quan, additional, Wong, Wai Kwan, additional, Tan, Brian Zi Yan, additional, Maiwald, Matthias, additional, Tee, Nancy Wen Sim, additional, Barkham, Timothy, additional, Koh, Tse Hsien, additional, Dalsgaard, Anders, additional, Chen, Swaine L., additional, Schlundt, Joergen, additional, and Ng, Lee Ching, additional
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- 2022
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14. Group B Streptococcus in retail food– beyond ST283 and raw fish
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Chau, Man Ling, primary, Chen, Swaine L., additional, Yap, Min, additional, Aung, Kyaw Thu, additional, Pahm Hartantyo, Sri Harminda, additional, Ariff, Ahmad Zhafir, additional, Kilari, Sreenivasulu, additional, Luc, Grisez, additional, Tan, Wei Ling, additional, Tan, Brian Z.Y., additional, Wong, Wai Kwan, additional, Gutiérrez, Ramona Alikiiteaga, additional, Ng, Lee Ching, additional, and Barkham, Timothy, additional
- Published
- 2022
- Full Text
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15. Rationalisation of Antifungal Properties of α-Helical Pore-Forming Peptide, Mastoparan B
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Lim, Edward Jianyang, primary, Leng, Eunice Goh Tze, additional, Tram, Nhan Dai Thien, additional, Periayah, Mercy Halleluyah, additional, Ee, Pui Lai Rachel, additional, Barkham, Timothy Mark Sebastian, additional, Poh, Zhi Sheng, additional, Verma, Navin Kumar, additional, and Lakshminarayanan, Rajamani, additional
- Published
- 2022
- Full Text
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16. GBS-SBG - GBS Serotyping by Genome Sequencing
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Tiruvayipati, Suma, primary, Tang, Wen Ying, additional, Barkham, Timothy M. S., additional, and Chen, Swaine L., additional
- Published
- 2021
- Full Text
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17. Heme cross-feeding can augment Staphylococcus aureusand Enterococcus faecalisdual species biofilms
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Ch’ng, Jun-Hong, Muthu, Mugil, Chong, Kelvin K L, Wong, Jun Jie, Tan, Casandra A Z, Koh, Zachary J S, Lopez, Daniel, Matysik, Artur, Nair, Zeus J, Barkham, Timothy, Wang, Yulan, and Kline, Kimberly A
- Abstract
The contribution of biofilms to virulence and as a barrier to treatment is well-established for Staphylococcus aureusand Enterococcus faecalis, both nosocomial pathogens frequently isolated from biofilm-associated infections. Despite frequent co-isolation, their interactions in biofilms have not been well-characterized. We report that in combination, these two species can give rise to augmented biofilms biomass that is dependent on the activation of E. faecalisaerobic respiration. In E. faecalis, respiration requires both exogenous heme to activate the cydAB-encoded heme-dependent cytochrome bd, and the availability of O2. We determined that the ABC transporter encoded by cydDCcontributes to heme import. In dual species biofilms, S. aureusprovides the heme to activate E. faecalisrespiration. S. aureusmutants deficient in heme biosynthesis were unable to augment biofilms whereas heme alone is sufficient to augment E. faecalismono-species biofilms. Our results demonstrate that S. aureus-derived heme, likely in the form of released hemoproteins, promotes E. faecalisbiofilm formation, and that E. faecalisgelatinase activity facilitates heme extraction from hemoproteins. This interspecies interaction and metabolic cross-feeding may explain the frequent co-occurrence of these microbes in biofilm-associated infections.
- Published
- 2022
- Full Text
- View/download PDF
18. Rational Substitution of ε-Lysine for α-Lysine Enhances the Cell and Membrane Selectivity of Pore-Forming Melittin
- Author
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Mayandi, Venkatesh, Xi, Qingxiao, Leng Goh, Eunice Tze, Koh, Siew Kwan, Jie Toh, Thomas Yong, Barathi, Veluchamy Amutha, Urf Turabe Fazil, Mobashar Hussain, Somaraju Chalasani, Madhavi Latha, Varadarajan, Jayasudha, Jeng Ting, Darren Shu, Beuerman, Roger W., Chan, Lai Wah, Agrawal, Rupesh, Sebastian Barkham, Timothy Mark, Zhou, Lei, Verma, Navin Kumar, and Lakshminarayanan, Rajamani
- Abstract
Here, we present a rational approach that enhances the membrane selectivity of a prolific pore-forming peptide, melittin, based on experimental observations that the cationic polymer, ε-polylysine, disrupts bacterial membranes with greater affinity over mammalian cells when compared to poly-l-lysine and poly-d-lysine. We systematically replaced three α-lysine residues in melittin with ε-lysine residues and identified key residues that are important for cytotoxicity. We then assessed the antimicrobial properties of the modified peptides which carry two or three ε-lysyl residues. Two modified melittin peptides displayed rapid bactericidal properties against antibiotic-resistant strains, low innate resistance development by pathogenic bacteria, remained nonimmunogenic for T lymphocytes, and increased bioavailability in tear fluids. In proof-of-concept in vivoexperiments, one of the peptides was noncytotoxic for ocular surfaces and had comparable antimicrobial efficacy to that of fluoroquinolone antibiotics. The results uncover a simple and potential strategy that can enhance the membrane selectivity of cytolytic peptides by ε-lysylation.
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- 2024
- Full Text
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19. Multifunctional Antimicrobial Nanofiber Dressings Containing ε-Polylysine for the Eradication of Bacterial Bioburden and Promotion of Wound Healing in Critically Colonized Wounds
- Author
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Mayandi, Venkatesh, Wen Choong, Alvin Chua, Dhand, Chetna, Lim, Fui Ping, Aung, Thet Tun, Sriram, Harini, Dwivedi, Neeraj, Periayah, Mercy Halleluyah, Sridhar, Sreepathy, Fazil, Mobashar Hussain Urf Turabe, Goh, Eunice Tze Leng, Orive, Gorka, W. Beuerman, Roger, Barkham, Timothy Mark Sebastian, Loh, Xian Jun, Liang, Zhao-Xun, Barathi, Veluchamy Amutha, Ramakrishna, Seeram, Chong, Si Jack, Verma, Navin Kumar, and Lakshminarayanan, Rajamani
- Abstract
Bacterial colonization of acute and chronic wounds is often associated with delayed wound healing and prolonged hospitalization. The rise of multi-drug resistant bacteria and the poor biocompatibility of topical antimicrobials warrant safe and effective antimicrobials. Antimicrobial agents that target microbial membranes without interfering with the mammalian cell proliferation and migration hold great promise in the treatment of traumatic wounds. This article reports the utility of superhydrophilic electrospun gelatin nanofiber dressings (NFDs) containing a broad-spectrum antimicrobial polymer, ε-polylysine (εPL), crosslinked by polydopamine (pDA) for treating second-degree burns. In a porcine model of partial thickness burns, NFDs promoted wound closure and reduced hypertrophic scarring compared to untreated burns. Analysis of NFDs in contact with the burns indicated that the dressings trap early colonizers and elicit bactericidal activity, thus creating a sterile wound bed for fibroblasts migration and re-epithelialization. In support of these observations, in porcine models of Pseudomonas aeruginosaand Staphylococcus aureuscolonized partial thickness burns, NFDs decreased bacterial bioburden and promoted wound closure and re-epithelialization. NFDs displayed superior clinical outcome than standard-of-care silver dressings. The excellent biocompatibility and antimicrobial efficacy of the newly developed dressings in pre-clinical models demonstrate its potential for clinical use to manage infected wounds without compromising tissue regeneration.
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- 2024
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20. Multilocus sequence typing database for Streptococcus agalactiae contains a spurious allele of the transketolase gene.
- Author
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Chen SL, Tiruvayipati S, Tang WY, and M S Barkham T
- Subjects
- Humans, Bacterial Proteins genetics, Databases, Genetic, Whole Genome Sequencing, Bacterial Typing Techniques methods, Streptococcus agalactiae genetics, Streptococcus agalactiae classification, Streptococcus agalactiae enzymology, Transketolase genetics, Transketolase metabolism, Alleles, Multilocus Sequence Typing methods
- Abstract
The tkt (transketolase) gene is one of the seven gene fragments used in the multilocus sequence typing (MLST) system for Streptococcus agalactiae . We discovered that the tkt_134 allele is derived from a homologous gene (which we designate tktX ) that is not present in all S. agalactiae ; all known strains that contain a match to the tkt_134 allele also contain a gene sequence that is much closer in sequence identity to the other non-tkt_134 alleles (i.e., the canonical tkt gene) in the database. Based on these data, the tkt_134 allele has been removed from the MLST database as of September 2021, and all sequence types containing tkt_134 have also been removed.IMPORTANCEMultilocus sequence typing (MLST) databases are a common good and remain important for research, medical, and epidemiological purposes. This remains true even in the context of widespread whole-genome sequencing. We discovered a contaminating allele of the tkt gene in the S. agalactiae MLST database that led to unstable, ambiguous, or erroneous MLST assignment. The allele has since been removed from the public database based on the results presented in this manuscript., Competing Interests: The authors declare no conflict of interest.
- Published
- 2024
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21. Fish-associated Streptococcus agalactiae ST283: first human cases reported from Malaysia.
- Author
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Zohari Z, Barkham T, Mohamad Maswan N, Chen SL, Muthanna A, Lee KW, Mohd Desa MN, Azmai MNA, Sither Joseph NM, and Amin-Nordin S
- Subjects
- Adult, Animals, Humans, Malaysia epidemiology, Fresh Water, Risk Factors, Streptococcus agalactiae genetics, Sepsis
- Abstract
In South East Asia, Streptococcus agalactiae ST283 causes sepsis in healthy adults. Raw freshwater fish consumption is the only known risk factor. These two case reports are the first from Malaysia. Although they cluster with Singapore ST283, the epidemiology is complicated by the flow of people and fish across borders.
- Published
- 2023
- Full Text
- View/download PDF
22. Heme cross-feeding can augment Staphylococcus aureus and Enterococcus faecalis dual species biofilms.
- Author
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Ch'ng JH, Muthu M, Chong KKL, Wong JJ, Tan CAZ, Koh ZJS, Lopez D, Matysik A, Nair ZJ, Barkham T, Wang Y, and Kline KA
- Subjects
- Biofilms, Heme, Virulence, Enterococcus faecalis genetics, Staphylococcus aureus genetics
- Abstract
The contribution of biofilms to virulence and as a barrier to treatment is well-established for Staphylococcus aureus and Enterococcus faecalis, both nosocomial pathogens frequently isolated from biofilm-associated infections. Despite frequent co-isolation, their interactions in biofilms have not been well-characterized. We report that in combination, these two species can give rise to augmented biofilms biomass that is dependent on the activation of E. faecalis aerobic respiration. In E. faecalis, respiration requires both exogenous heme to activate the cydAB-encoded heme-dependent cytochrome bd, and the availability of O
2 . We determined that the ABC transporter encoded by cydDC contributes to heme import. In dual species biofilms, S. aureus provides the heme to activate E. faecalis respiration. S. aureus mutants deficient in heme biosynthesis were unable to augment biofilms whereas heme alone is sufficient to augment E. faecalis mono-species biofilms. Our results demonstrate that S. aureus-derived heme, likely in the form of released hemoproteins, promotes E. faecalis biofilm formation, and that E. faecalis gelatinase activity facilitates heme extraction from hemoproteins. This interspecies interaction and metabolic cross-feeding may explain the frequent co-occurrence of these microbes in biofilm-associated infections., (© 2022. The Author(s).)- Published
- 2022
- Full Text
- View/download PDF
23. Viral Dynamics and Immune Correlates of Coronavirus Disease 2019 (COVID-19) Severity.
- Author
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Young BE, Ong SWX, Ng LFP, Anderson DE, Chia WN, Chia PY, Ang LW, Mak TM, Kalimuddin S, Chai LYA, Pada S, Tan SY, Sun L, Parthasarathy P, Fong SW, Chan YH, Tan CW, Lee B, Rötzschke O, Ding Y, Tambyah P, Low JGH, Cui L, Barkham T, Lin RTP, Leo YS, Renia L, Wang LF, and Lye DC
- Subjects
- Antibodies, Viral, Female, Humans, Immunoglobulin M, Male, Middle Aged, Prospective Studies, SARS-CoV-2, Seroconversion, COVID-19, Pneumonia, Viral
- Abstract
Background: Key knowledge gaps remain in the understanding of viral dynamics and immune response of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection., Methods: We evaluated these characteristics and established their association with clinical severity in a prospective observational cohort study of 100 patients with PCR-confirmed SARS-CoV-2 infection (mean age, 46 years; 56% male; 38% with comorbidities). Respiratory samples (n = 74) were collected for viral culture, serum samples for measurement of IgM/IgG levels (n = 30), and plasma samples for levels of inflammatory cytokines and chemokines (n = 81). Disease severity was correlated with results from viral culture, serologic testing, and immune markers., Results: Fifty-seven (57%) patients developed viral pneumonia, of whom 20 (20%) required supplemental oxygen, including 12 (12%) with invasive mechanical ventilation. Viral culture from respiratory samples was positive for 19 of 74 patients (26%). No virus was isolated when the PCR cycle threshold (Ct) value was >30 or >14 days after symptom onset. Seroconversion occurred at a median (IQR) of 12.5 (9-18) days for IgM and 15.0 (12-20) days for IgG; 54/62 patients (87.1%) sampled at day 14 or later seroconverted. Severe infections were associated with earlier seroconversion and higher peak IgM and IgG levels. Levels of IP-10, HGF, IL-6, MCP-1, MIP-1α, IL-12p70, IL-18, VEGF-A, PDGF-BB, and IL-1RA significantly correlated with disease severity., Conclusions: We found virus viability was associated with lower PCR Ct value in early illness. A stronger antibody response was associated with disease severity. The overactive proinflammatory immune signatures offer targets for host-directed immunotherapy, which should be evaluated in randomized controlled trials., (© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)
- Published
- 2021
- Full Text
- View/download PDF
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