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Background: Clinical significance of Eschericia coli is due to its capacity to develop resistance against many antibiotics specially carbapenem by producing carbapenemase which limits treatment options. blaNDM and blaVIM genes are responsible for this multi-drug-resistance. This is an alarming condition for society as well as clinician because they are very difficult to treat due to limited options of antibiotics and its high virulence. Aims and Objectives: The study was conducted to detect antibiogram pattern and prevalence of blaNDM and blaVIM genes among carbapenem resistant E. coli isolates in a tertiary care hospital. Our study will also help to identify molecular basis of Carbapenem resistance including treatment guideline. Materials and Methods: Cross-sectional study was performed during January’2021 to June’2022 time period. Identification of E. coli was followed by standard protocol and antibiotic sensitivity was done by Kirby-Bauer disk-diffusion method following CLSI guideline, using VITEK-2D-SYSTEM. Detection of genes was done by polymerase chain reaction (PCR). Results: Out of 1867 samples, 161 isolates were identified as E. coli, among which 90 were resistant to carbapenem. Among those, 50 (31%) were resistant to all three carbapenems. Among those, 100% were resistant to ampicillin, amoxycillin-clavulanic acid, cefuroxime, cefuroxime-axetil, cefoperazone-sulbactam, ceftriaxone, cefepime, piperacillin-tazobactam, nalidixic acid, ciprofloxacin; 52% were resistant to amikacin; 54% were resistant to gentamicin; 86% were resistant to cotrimoxazole; 22% were resistant to nitrofurantoin and 96% were sensitive to tigecycline; 100% were intermediate sensitive to colistin. blaNDM gene is detected in 17 (34%) isolates and blaVIM gene is detected in 2 (4%) isolates by PCR. Conclusion: E. coli leads to common clinical presentations such as urinary tract infection, blood stream infection, pneumonia, and wound infection. High burden of carbapenem resistant E. coli was associated with urinary indoor samples. Rising incidence of multi-drug-resistance occurs due to lack of infection control measures, irrational use of antibiotics. Continuous surveillance will prevent development of multi-drug-resistance and help to improve treatment guideline.

Background: Clinical significance of Eschericia coli is due to its capacity to develop resistance against many antibiotics specially carbapenem by producing carbapenemase which limits treatment options. blaNDM and blaVIM genes are responsible for this multi-drug-resistance. This is an alarming condition for society as well as clinician because they are very difficult to treat due to limited options of antibiotics and its high virulence. Aims and Objectives: The study was conducted to detect antibiogram pattern and prevalence of blaNDM and blaVIM genes among carbapenem resistant E. coli isolates in a tertiary care hospital. Our study will also help to identify molecular basis of Carbapenem resistance including treatment guideline. Materials and Methods: Cross-sectional study was performed during January'2021 to June'2022 time period. Identification of E. coli was followed by standard protocol and antibiotic sensitivity was done by Kirby-Bauer disk-diffusion method following CLSI guideline, using VITEK-2D-SYSTEM. Detection of genes was done by polymerase chain reaction (PCR). Results: Out of 1867 samples, 161 isolates were identified as E. coli, among which 90 were resistant to carbapenem. Among those, 50 (31%) were resistant to all three carbapenems. Among those, 100% were resistant to ampicillin, amoxycillin-clavulanic acid, cefuroxime, cefuroxime-axetil, cefoperazone-sulbactam, ceftriaxone, cefepime, piperacillin-tazobactam, nalidixic acid, ciprofloxacin; 52% were resistant to amikacin; 54% were resistant to gentamicin; 86% were resistant to cotrimoxazole; 22% were resistant to nitrofurantoin and 96% were sensitive to tigecycline; 100% were intermediate sensitive to colistin. blaNDM gene is detected in 17 (34%) isolates and blaVIM gene is detected in 2 (4%) isolates by PCR. Conclusion: E. coli leads to common clinical presentations such as urinary tract infection, blood stream infection, pneumonia, and wound infection. High burden of carbapenem resistant E. coli was associated with urinary indoor samples. Rising incidence of multi-drug-resistance occurs due to lack of infection control measures, irrational use of antibiotics. Continuous surveillance will prevent development of multi-drug-resistance and help to improve treatment guideline. [ABSTRACT FROM AUTHOR]

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a great public health problem and is associated with many disease outbreaks and high mortality rates. Alarmingly, K. pneumoniae has been isolated from food in several recent studies. This study aimed to investigate the prevalence and characteristics of CRKP in food samples from Egypt. Methods: A total of 311 food samples (including 116 minced meat, 92 chicken meat, 75 diced meat, and 28 mutton) were collected from local markets in Egypt and were screened for CRKP with the determination of their antimicrobial resistance profiles. The whole genome sequence was done for 23 CRKP isolates to clarify the relationship between CRKP from food and human cases in Egypt using the SNP core genome. The conjugation probability of the blaNDM-5 harboring plasmid was identified using oriTfinder Results: CRKP was isolated from 11% (35/311) of the samples, with 45.71% (16/35) of them showing resistance to colistin, one of the last-resort options for treating CRKP-mediated infections. In addition to the carbapenem and colistin resistance, the CRKP isolates frequently exhibited resistance to multiple antimicrobials including β-lactams, fluoroquinolones, aminoglycosides, tetracyclines, and chloramphenicol. In addition, most of the CRKP were potentially hypervirulent K. pneumoniae (HvKP) identified as phylogroup Kp1 and of high-risk groups as detected in STs reported in many human outbreaks globally, such as ST383 and ST147. The core-genome phylogeny showed similarities between the isolates from this study and those previously isolated from clinical human samples in Egypt. In addition, analysis of the plasmid on which blaNDM is encoded revealed that several antimicrobial resistance genes such as blaOXA-9, blaCTX-M-15, aac(6′)-Ib, qnrS1, and several virulence genes are encoded on the same plasmid. Conclusions: This study is significant for food safety and public health and is important to further identify the change in the epidemiology of CRKP infections, especially the consumption of contaminated food products.

Kexin Guo,1,* Zanzan Zhao,1,* Yu Yang,1 Xiawei Jiang,1 Hao Xu,2 Fangfang Tao,1 Ye Xu,1 Wenhong Liu1 1School of Basic Medical Sciences, Zhejiang Chinese Medical University, Hangzhou, People’s Republic of China; 2Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, People’s Republic of China*These authors contributed equally to this workCorrespondence: Wenhong Liu, School of Basic Medical Sciences, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 310053, People’s Republic of China, Email lwh@zcmu.edu.cnBackground: To explore the plasmid characteristics and transfer mechanisms of an extensive drug resistant (XDR) clinical isolate, Citrobacter portucalensis L2724hy, co-producing blaSFO-1, blaNDM-1, and blaKPC-2.Methods: Species confirmation of L2724hy was achieved through 16S rRNA sequencing and Average Nucleotide Identity (ANI) analysis. Antimicrobial susceptibility testing (AST) employed the agar dilution and micro broth dilution methods. Identification of resistance genes was carried out by PCR and whole-genome sequencing (WGS). Essential resistance gene locations were verified by S1 nuclease pulsed-field gel electrophoresis (S1-PFGE) and southern hybridization experiments. Subsequent WGS data analysis delved into drug resistance genes and plasmids.Results: The confirmation of the strain L2724hy as an extensive drug-resistant Citrobacter portucalensis, resistant to almost all antibiotics tested except polymyxin B and tigecycline, was achieved through 16S rRNA sequencing, ANI analysis and AST results. WGS and subsequent analysis revealed L2724hy carrying blaSFO-1, blaNDM-1, and blaKPC-2 on plasmids of various sizes. The uncommon ESBL gene blaSFO-1 coexists with the fosA3 gene on an IncFII plasmid, featuring the genetic environment IS 26-fosA3-IS 26-ampR-blaSFO-1-IS 26. The blaNDM-1 was found on an IncX3 plasmid, coexisting with blaSHV-12, displaying the sequence IS 5-IS 3000-IS 3000-Tn 2-blaNDM-1-ble-trpF-dsbD-cutA-gros-groL, lacking ISAa125. The blaKPC-2 is located on an unclassified plasmid, exhibiting the sequence Tn 2-tnpR-ISKpn27-blaKPC-2-ISKpn6-korC. Conjugation assays confirmed the transferability of both blaNDM-1 and blaKPC-2.Conclusion: We discovered the coexistence of blaSFO-1, blaNDM-1, and blaKPC-2 in C. portucalensis for the first time, delving into plasmid characteristics and transfer mechanisms. Our finding highlights the importance of vigilant monitoring of drug-resistance genes and insertion elements in uncommon strains.Keywords: Citrobacter spp, XDR, blaSFO, blaNDM, blaKPC, IncFII

ABSTRACT: Objectives: The blaNDM gene was prevalent among children and became the predominant cause of severe infection in infants and children. This study aimed to investigate the epidemiology and molecular characteristics of blaNDM in Enterobacteriaceae among children in China. Methods: Carbapenem-resistant Enterobacteriaceae (CRE) were collected in the Children's Hospital of Fudan University from January 2016 to December 2022. Five carbapenemase genes (blaKPC, blaNDM, blaVIM, blaIMP, blaOXA-48) were screened by PCR method. Multilocus sequence typing (MLST) was conducted for phylogenetic analyses. blaNDM-carrying plasmids were typed by PCR-based Incompatibility (Inc) typing method. Moreover, plasmid comparison was performed with 213 publicly available IncX3 plasmids. Results: A total of 330 CRE strains were enrolled, 96.4% of which carried carbapenemase genes. blaNDM gene accounted for 64.8% (214 strains) and included four variants, including blaNDM-1 (59.8%), blaNDM-5 (39.3%), blaNDM-7 (0.5%), and blaNDM-9 (0.5%). There were no predominant MLST lineages of blaNDM carrying strains. IncX3 was the major plasmid carrying blaNDM-1 (68.0%) and blaNDM-5 (72.6%) and was dominant in blaNDM-Klebsiella penumoniae (79.8%), blaNDM-Escherichia coli (58.2%), and blaNDM-Enterobacter cloacae (61.0%), respectively. Most (79.0%) clinical IncX3 plasmids in the world carried blaNDM, and the prevalence of blaNDM in IncX3 plasmids was more common in China (95.8%) than other countries (58.1%, P

Abstract Background Escherichia. coli is the most frequent host for New Delhi metallo-β-lactamase (NDM) which hydrolyzes almost all β-lactams except aztreonam. The worldwide spread of blaNDM-carrying E. coli heavily threatens public health. Objective This study aimed to explore the global genomic epidemiology of blaNDM- carrying E. coli isolates, providing information for preventing the dissemination of such strains. Methods Global E. coli genomes were downloaded from NCBI database and blaNDM was detected using BLASTP. Per software was used to extract meta information on hosts, resources, collection data, and countries of origin from GenBank. The sequence types (STs) and distribution of antimicrobial resistance gene (ARG) were analyzed by CLC Workbench; Plasmid replicons, serotypes and virulence genes (VFs) were analyzed by submitting the genomes to the websites. Statistical analyses were performed to access the relationships among ARGs and plasmid replicons. Results Until March 2023, 1,774 out of 33,055 isolates collected during 2003–2022 were found to contain blaNDM in total. Among them, 15 blaNDM variants were found with blaNDM-5 (74.1%) being most frequent, followed by blaNDM-1 (16.6%) and blaNDM-9 (4.6%). Among the 213 ARGs identified, 27 blaCTX-M and 39 blaTEM variants were found with blaCTX-M-15 (n = 438, 24.7%) and blaTEM-1B (n = 1092, 61.6%) being the most frequent ones, respectively. In addition, 546 (30.8%) plasmids mediated ampC genes, 508 (28.6%) exogenously acquired 16 S rRNA methyltransferase encoding genes and 262 (14.8%) mcr were also detected. Among the 232 distinct STs, ST167 (17.2%) were the most prevalent. As for plasmids, more than half of isolates contained IncFII, IncFIB and IncX3. The VF terC, gad, traT and iss as well as the serotypes O101:H9 (n = 231, 13.0%), O8:H9 (n = 115, 6.5%) and O9:H30 (n = 99, 5.6%) were frequently observed. Conclusions The study delves into the intricate relationship between plasmid types, virulence factors, and ARGs, which provides valuable insights for clinical treatment and public health interventions, and serves as a critical resource for guiding future research, surveillance, and implementation of effective strategies to address the challenges posed by blaNDM-carrying E. coli. The findings underscore the urgent need for sustained global collaboration, surveillance efforts, and antimicrobial stewardship to mitigate the impact of these highly resistant strains on public health.

Background: Escherichia. coli is the most frequent host for New Delhi metallo-β-lactamase (NDM) which hydrolyzes almost all β-lactams except aztreonam. The worldwide spread of blaNDM-carrying E. coli heavily threatens public health. Objective: This study aimed to explore the global genomic epidemiology of blaNDM- carrying E. coli isolates, providing information for preventing the dissemination of such strains. Methods: Global E. coli genomes were downloaded from NCBI database and blaNDM was detected using BLASTP. Per software was used to extract meta information on hosts, resources, collection data, and countries of origin from GenBank. The sequence types (STs) and distribution of antimicrobial resistance gene (ARG) were analyzed by CLC Workbench; Plasmid replicons, serotypes and virulence genes (VFs) were analyzed by submitting the genomes to the websites. Statistical analyses were performed to access the relationships among ARGs and plasmid replicons. Results: Until March 2023, 1,774 out of 33,055 isolates collected during 2003–2022 were found to contain blaNDM in total. Among them, 15 blaNDM variants were found with blaNDM-5 (74.1%) being most frequent, followed by blaNDM-1 (16.6%) and blaNDM-9 (4.6%). Among the 213 ARGs identified, 27 blaCTX-M and 39 blaTEM variants were found with blaCTX-M-15 (n = 438, 24.7%) and blaTEM-1B (n = 1092, 61.6%) being the most frequent ones, respectively. In addition, 546 (30.8%) plasmids mediated ampC genes, 508 (28.6%) exogenously acquired 16 S rRNA methyltransferase encoding genes and 262 (14.8%) mcr were also detected. Among the 232 distinct STs, ST167 (17.2%) were the most prevalent. As for plasmids, more than half of isolates contained IncFII, IncFIB and IncX3. The VF terC, gad, traT and iss as well as the serotypes O101:H9 (n = 231, 13.0%), O8:H9 (n = 115, 6.5%) and O9:H30 (n = 99, 5.6%) were frequently observed. Conclusions: The study delves into the intricate relationship between plasmid types, virulence factors, and ARGs, which provides valuable insights for clinical treatment and public health interventions, and serves as a critical resource for guiding future research, surveillance, and implementation of effective strategies to address the challenges posed by blaNDM-carrying E. coli. The findings underscore the urgent need for sustained global collaboration, surveillance efforts, and antimicrobial stewardship to mitigate the impact of these highly resistant strains on public health. [ABSTRACT FROM AUTHOR]

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a great public health problem and is associated with many disease outbreaks and high mortality rates. Alarmingly, K. pneumoniae has been isolated from food in several recent studies. This study aimed to investigate the prevalence and characteristics of CRKP in food samples from Egypt. A total of 311 food samples (including 116 minced meat, 92 chicken meat, 75 diced meat, and 28 mutton) were collected from local markets in Egypt and were screened for CRKP with the determination of their antimicrobial resistance profiles. The whole genome sequence was done for 23 CRKP isolates to clarify the relationship between CRKP from food and human cases in Egypt using the SNP core genome. The conjugation probability of the bla NDM-5 harboring plasmid was identified using oriTfinder CRKP was isolated from 11% (35/311) of the samples, with 45.71% (16/35) of them showing resistance to colistin, one of the last-resort options for treating CRKP-mediated infections. In addition to the carbapenem and colistin resistance, the CRKP isolates frequently exhibited resistance to multiple antimicrobials including β-lactams, fluoroquinolones, aminoglycosides, tetracyclines, and chloramphenicol. In addition, most of the CRKP were potentially hypervirulent K. pneumoniae (HvKP) identified as phylogroup Kp1 and of high-risk groups as detected in STs reported in many human outbreaks globally, such as ST383 and ST147. The core-genome phylogeny showed similarities between the isolates from this study and those previously isolated from clinical human samples in Egypt. In addition, analysis of the plasmid on which bla NDM is encoded revealed that several antimicrobial resistance genes such as bla OXA-9 , bla CTX-M-15 , aac(6′)-Ib, qnrS1, and several virulence genes are encoded on the same plasmid. This study is significant for food safety and public health and is important to further identify the change in the epidemiology of CRKP infections, especially the consumption of contaminated food products. [ABSTRACT FROM AUTHOR]

ABSTRACT: Carbapenems and colistin are vital antimicrobials used to treat Enterobacteriaceae-caused infections. The present study aimed to characterize the coexistence mechanism of carbapenem and colistin resistance in an Escherichia coli isolated from retail chicken meat. A total of 4 E. coli isolates co-harboring carbapenem resistance gene blaNDM (2 E. coli isolates with blaNDM-5 and 2 with blaNDM-9) and colistin resistance gene mcr-1. Antimicrobial susceptibility testing exhibited that all the 4 E. coli strains had multidrug resistance profile and consistent with the resistance genes they carried. MLST showed that 3 E. coli isolates belonged to a pathogenic E. coli lineage ST354, which is closely associated with human infections and pose a serious threat to public health. Whole genome sequencing (WGS) showed that 4 mcr-1-positive plasmids with sizes of 60.4 kb to 67.4 kb all belonged to the IncI2 type. A total of 5 blaNDM-harboring plasmids ranged from 99.0 kb to 138.3 kb, among which 4 plasmids belonged to unknow type and only pCS5L-NDM belonged to IncFIA/IncFIB group of hybrid plasmids, a novel carrier for blaNDM. Comparative analysis exhibited that the mcr-1 or blaNDM-carrying plasmids of E. coli strains from chicken meat showed high identity with that from Enterobacteriaceae of human origin, which indicated the risk of mcr-1 or blaNDM dissemination from retail meat to human. The simultaneous occurrence of mcr-1 and blaNDM in E. coli emphasizes the significant of antimicrobial resistance surveillance in retail meat.

ABSTRACT blaNDM, the most prevalent carbapenemase among carbapenem-resistant Enterobacteriaceae, is thought to have emerged in India, as its initial detection in 2008 was linked to this country, and subsequent retrospective surveys had so far established the earliest blaNDM-positive strains to be isolated in India in 2005. Molecular dating and analyses suggest blaNDM emerged within Acinetobacter species decades prior to 2005 on a Tn125 transposon. Despite early reports of elevated rates of carbapenem-resistant Acinetobacter species in Israel starting in the 1990s, limited molecular data are available from this location. We searched for blaNDM among Acinetobacter species isolated in Israel between 2001 and 2006. One A. junii strain, Ajun-H1-3, isolated in January 2004, carried blaNDM-1 within a Tn125-like transposon on a 49-kb plasmid, pNDM-Ajun-H1-3, making Ajun-H1-3 the earliest NDM-positive isolate observed to date. The pNDM-Ajun-H1-3 plasmid matched numerous BJ01-like NDM-positive plasmids identified from 2005 onward in Acinetobacter species as well as Enterobacterales. These results indicate the need for further retrospective work on global strain archives to shed light on the conditions favoring the emergence as well as subsequent evolution and spread of blaNDM.IMPORTANCEThis study presents the earliest observation of blaNDM-1, isolated in a geographical region distant from where it is believed to have originated. In doing so, this study provides novel insights into the emergence and spread of blaNDM, the most prevalent carbapenemase among carbapenem-resistant Enterobacteriaceae, and its associated mobile genetic elements. It also sheds light on the conditions that foster the evolution of antimicrobial resistance, one of the greatest public health challenges we face.

Background: The carbapenem-resistant Klebsiella pneumoniae poses a serious threat to public health because carbapenems are used as a final resort to treat K. pneumoniae-mediated infections in humans. Methods: Samples were collected from various clinical specimens including skin swabs, anal swabs, wound swabs, oral swabs, and sputum by the standard method and K. pneumoniae strains were isolated. Biofilm-forming characters were determined. The antibiotic resistance pattern was analyzed by the Kirby–Bauer disk diffusion method. Carbapenem resistance properties were tested using the imipenem and meropenem antibiotics. The carbapenemase genes (blaKPC and blaNDM) were determined. Results: A total of 11 cephalosporin-resistant K. pneumoniae (CRKP) strains were isolated from the samples. The screened CRKP strains exhibited multi-drug resistance and non-susceptible to imipenem, ceftazidime, piperacillin, ceftriaxone, cefazolin, ampicillin, aztreonam, and cefotetan antibiotics. A total of 79.4 % K. pneumoniae isolates showed positive results on String-forming test. About 82.1 % of isolates showed mucoid colonies and 59 % of K. pneumoniae strains formed biofilm (p

Abstract Background Colistin is a last-resort antibiotic used in extreme cases of multi-drug resistant (MDR) Gram-negative bacterial infections. Colistin resistance has increased in recent years and often goes undetected due to the inefficiency of predominantly used standard antibiotic susceptibility tests (AST). To address this challenge, we aimed to detect the prevalence of colistin resistance strains through both Vitek®2 and broth micro-dilution. We investigated 1748 blood, tracheal aspirate, and pleural fluid samples from the Intensive Care Unit (ICU), Neonatal Intensive Care Unit (NICU), and Tuberculosis and Respiratory Disease centre (TBRD) in an India hospital. Whole-genome sequencing (WGS) of extremely drug-resitant (XDR) and pan-drug resistant (PDR) strains revealed the resistance mechanisms through the Resistance Gene Identifier (RGI.v6.0.0) and Snippy.v4.6.0. Abricate.v1.0.1, PlasmidFinder.v2.1, MobileElementFinder.v1.0.3 etc. detected virulence factors, and mobile genetic elements associated to uncover the pathogenecity and the role of horizontal gene transfer (HGT). Results This study reveals compelling insights into colistin resistance among global high-risk clinical isolates: Klebsiella pneumoniae ST147 (16/20), Pseudomonas aeruginosa ST235 (3/20), and ST357 (1/20). Vitek®2 found 6 colistin-resistant strains (minimum inhibitory concentrations, MIC = 4 μg/mL), while broth microdilution identified 48 (MIC = 32–128 μg/mL), adhering to CLSI guidelines. Despite the absence of mobile colistin resistance (mcr) genes, mechanisms underlying colistin resistance included mgrB deletion, phosphoethanolamine transferases arnT, eptB, ompA, and mutations in pmrB (T246A, R256G) and eptA (V50L, A135P, I138V, C27F) in K. pneumoniae. P. aeruginosa harbored phosphoethanolamine transferases basS/pmrb, basR, arnA, cprR, cprS, alongside pmrB (G362S), and parS (H398R) mutations. Both strains carried diverse clinically relevant antimicrobial resistance genes (ARGs), including plasmid-mediated bla NDM-5 (K. pneumoniae ST147) and chromosomally mediated bla NDM-1 (P. aeruginosa ST357). Conclusion The global surge in MDR, XDR and PDR bacteria necessitates last-resort antibiotics such as colistin. However, escalating resistance, particularly to colistin, presents a critical challenge. Inefficient colistin resistance detection methods, including Vitek2, alongside limited surveillance resources, accentuate the need for improved strategies. Whole-genome sequencing revealed alarming colistin resistance among K. pneumoniae and P. aeruginosa in an Indian hospital. The identification of XDR and PDR strains underscores urgency for enhanced surveillance and infection control. SNP analysis elucidated resistance mechanisms, highlighting the complexity of combatting resistance.

Background: Colistin is a last-resort antibiotic used in extreme cases of multi-drug resistant (MDR) Gram-negative bacterial infections. Colistin resistance has increased in recent years and often goes undetected due to the inefficiency of predominantly used standard antibiotic susceptibility tests (AST). To address this challenge, we aimed to detect the prevalence of colistin resistance strains through both Vitek®2 and broth micro-dilution. We investigated 1748 blood, tracheal aspirate, and pleural fluid samples from the Intensive Care Unit (ICU), Neonatal Intensive Care Unit (NICU), and Tuberculosis and Respiratory Disease centre (TBRD) in an India hospital. Whole-genome sequencing (WGS) of extremely drug-resitant (XDR) and pan-drug resistant (PDR) strains revealed the resistance mechanisms through the Resistance Gene Identifier (RGI.v6.0.0) and Snippy.v4.6.0. Abricate.v1.0.1, PlasmidFinder.v2.1, MobileElementFinder.v1.0.3 etc. detected virulence factors, and mobile genetic elements associated to uncover the pathogenecity and the role of horizontal gene transfer (HGT). Results: This study reveals compelling insights into colistin resistance among global high-risk clinical isolates: Klebsiella pneumoniae ST147 (16/20), Pseudomonas aeruginosa ST235 (3/20), and ST357 (1/20). Vitek®2 found 6 colistin-resistant strains (minimum inhibitory concentrations, MIC = 4 μg/mL), while broth microdilution identified 48 (MIC = 32–128 μg/mL), adhering to CLSI guidelines. Despite the absence of mobile colistin resistance (mcr) genes, mechanisms underlying colistin resistance included mgrB deletion, phosphoethanolamine transferases arnT, eptB, ompA, and mutations in pmrB (T246A, R256G) and eptA (V50L, A135P, I138V, C27F) in K. pneumoniae. P. aeruginosa harbored phosphoethanolamine transferases basS/pmrb, basR, arnA, cprR, cprS, alongside pmrB (G362S), and parS (H398R) mutations. Both strains carried diverse clinically relevant antimicrobial resistance genes (ARGs), including plasmid-mediated blaNDM-5 (K. pneumoniae ST147) and chromosomally mediated blaNDM-1 (P. aeruginosa ST357). Conclusion: The global surge in MDR, XDR and PDR bacteria necessitates last-resort antibiotics such as colistin. However, escalating resistance, particularly to colistin, presents a critical challenge. Inefficient colistin resistance detection methods, including Vitek2, alongside limited surveillance resources, accentuate the need for improved strategies. Whole-genome sequencing revealed alarming colistin resistance among K. pneumoniae and P. aeruginosa in an Indian hospital. The identification of XDR and PDR strains underscores urgency for enhanced surveillance and infection control. SNP analysis elucidated resistance mechanisms, highlighting the complexity of combatting resistance. [ABSTRACT FROM AUTHOR]

The widespread transmission of blaNDM among livestock and the live poultry industry attracts considerable public attention. However, studies have not yet addressed its impact on public health in live poultry markets (LPMs). Herein, we investigated the prevalence and genomic epidemiology of blaNDM-positive bacteria in various niches, and explored the transmission patterns of blaNDM within LPMs. Samples were collected between 2019 and 2022 from two LPMs in China. blaNDM was most prevalent in wastewater (35/66, 53.03%). All vegetable samples were negative for blaNDM. blaNDM was mainly distributed among Escherichia coli (266/336, 79.17%), Klebsiella pneumoniae (62/336, 18.45%), and Acinetobacter baumannii (3/336, 0.89%). Some novel hosts, including Pseudomonas monteilii and Pseudomonas otitis, were also identified. Diverse variants blaNDM-1, blaNDM-5, blaNDM-9, blaNDM-13, and blaNDM-27 were identified. The blaNDM-positive E. coli ST2659 was dominant. blaNDM was found to coexist with mcr-1 (4/51, 7.84%). Horizontal gene transfer plays a vital role in blaNDM transmission within the LPMs. Some blaNDM-harboring clones transfer among animals and the environment through the food chain and close contact. More efforts are needed to curb the transmission trend of blaNDM among humans, animals, and the environment within LPMs. [ABSTRACT FROM AUTHOR]

Introduction: Bacterial resistance is a major threat to public health worldwide. To gain an understanding of the clinical infection distribution, drug resistance information, and genotype of CRE in Dongguan, China, as well as the resistance of relevant genotypes to CAZ-AVI, this research aims to improve drug resistance monitoring information in Dongguan and provide a reliable basis for the clinical control and treatment of CRE infection. Methods: VITEK-2 Compact automatic analyzer was utilized to identify 516 strains of CRE collected from January 2017 to June 2023. To determine drug sensitivity, the K-B method, E-test, and MIC methods were used. From June 2022 to June 2023, 80 CRE strains were selected, and GeneXpert Carba-R was used to detect and identify the genotype of the carbapenemase present in the collected CRE strains. An in-depth analysis was conducted on the CAZ-AVI in vitro drug sensitivity activity of various genotypes of CRE, and the results were statistically evaluated using SPSS 23.0 and WHONET 5.6 software. Results: This study identified 516 CRE strains, with the majority (70.16%) being K.pneumoniae, followed by E.coli (18.99%). Respiratory specimens had highest detection rate with 53.77% identified, whereas urine specimens had the second highest detection rate with 17.99%. From June 2022 to June 2023, 95% of the strains tested using the CRE GeneXpert Carba-R assay possessed carbapenemase genes, of which 32.5% were blaNDM strains and 61.25% blaKPC strains. The results showed that CRE strains containing blaKPC had a significantly higher rate of resistance to amikacin, cefepime, and aztreonam than those harboring blaNDM. Conclusions: The CRE strains isolated from Dongguan region demonstrated a high resistance rate to various antibiotics used in clinical practice but a low resistance rate to tigecycline. These strains produce Class A serine carbapenemases and Class B metals β-lactamases, with the majority of them carrying blaNDM and blaKPC. Notably, CRE strains with blaKPC and blaNDM had significantly lower resistance rates to tigecycline. CAZ-AVI showed a good sensitivity rate with no resistance to CRE strains carrying blaKPC. Therefore, CAZ-AVI and tigecycline should be used as a guide for rational use of antibiotics in clinical practice to effectively treat CRE. [ABSTRACT FROM AUTHOR]

Background: Multi-Drug-ResistantKlebsiella pneumoniae (MDR K. pneumoniae) is considered as an important opportunistic pathogen, which causes life threatening infections. K. pneumoniae is known to causes life-threatening infections. Objective: The objective of this study is to detect some β-lactamase genes in Klebsiella pneumoniae. Methods: Thirty-five K. pneumoniae isolates were obtained from some hospitals in Baghdad City between October 2022 and February 2023. The identification of K. pneumoniae isolates was done phenotypically by the automated VITEK II system and genotypically by amplification of the rpob gene. The antibiotic susceptibility and detection of some β-lactamase genes were tested for all isolates. Results: The results showed that the K. pneumoniae isolates were resistant to most antibiotics used. A high percentage of K. pneumoniae isolates were resistant to cefixime, cefpodoxime, norfloxacin and doxycycline as 100% followed by ceftriaxone, ceftazidime, ticarcillin/clavulanate, ticarcillin, ceftazidime, tobramycin, and moxifloxacin (97.2%, 91.7%, 91.7%, 94.4%, 94.4%, and 94.4%, respectively). Furthermore, approximately 94.4% of the isolates were MDR. In addition, the molecular methods only detected the blaNDM and blaTEM genes as 33.3% and 75.6% of in the K. pneumoniae isolates, respectively, while the blaVIM, blaCTX−M, and blaKPC genes were not observed in K. pneumoniae isolates. Conclusions: β-lactam antibiotics, including carbapenems, are widely used to treat bacterial infections; however, an increase in antibiotic resistance due to β-lactamases limits the effectiveness of these antibiotics. Therefore, alternative treatment methods are required to control these resistant isolates. [ABSTRACT FROM AUTHOR]

Background: Carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) co-producing blaKPC and blaNDM poses a serious threat to public health. This study aimed to investigate the mechanisms underlying the resistance and virulence of CR-hvKP isolates collected from a Chinese hospital, with a focus on blaKPC and blaNDM dual-positive hvKP strains. Methods: Five CR-hvKP strains were isolated from a teaching hospital in China. Antimicrobial susceptibility and plasmid stability testing, plasmid conjugation, pulsed-field gel electrophoresis, and whole-genome sequencing (WGS) were performed to examine the mechanisms of resistance and virulence. The virulence of CR-hvKP was evaluated through serum-killing assay and Galleria mellonella lethality experiments. Phylogenetic analysis based on 16 highly homologous carbapenem-resistant K. pneumoniae (CRKP) producing KPC-2 isolates from the same hospital was conducted to elucidate the potential evolutionary pathway of CRKP co-producing NDM and KPC. Results: WGS revealed that five isolates individually carried three unique plasmids: an IncFIB/IncHI1B-type virulence plasmid, IncFII/IncR-type plasmid harboring KPC-2 and IncC-type plasmid harboring NDM-1. The conjugation test results indicated that the transference of KPC-2 harboring IncFII/IncR-type plasmid was unsuccessful on their own, but could be transferred by forming a hybrid plasmid with the IncC plasmid harboring NDM. Further genetic analysis confirmed that the pJNKPN26-KPC plasmid was entirely integrated into the IncC-type plasmid via the copy-in route, which was mediated by TnAs1 and IS26. Conclusion: KPC-NDM-CR-hvKP likely evolved from a KPC-2-CRKP ancestor and later acquired a highly transferable blaNDM-1 plasmid. ST11-KL64 CRKP exhibited enhanced plasticity. The identification of KPC-2-NDM-1-CR-hvKP highlights the urgent need for effective preventive strategies against aggravated accumulation of resistance genes. [ABSTRACT FROM AUTHOR]

Background: The increasing global concern regarding antibiotic resistance necessitates in-depth studies to comprehend the phenotypic and genotypic characteristics of resistant bacterial strains. This study aimed to investigate the prevalence, antibiotic resistance profiles, and molecular characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates in an Iranian referral pediatrics hospital. Methods: In this study, we examined CRKP isolates collected from hospitalized pediatric patients across various wards. The isolates underwent antimicrobial susceptibility testing, the polymerase chain reaction (PCR) analysis for carbapenemase genes (blaNDM, blaVIM and blaIMP), and genetic relatedness assessment using pulsed-field gel electrophoresis (PFGE). Results: Among 166 K. pneumoniae isolates, 54 (32.5%) exhibited resistance to carbapenems. Notably, all these resistant isolates were resistant to imipenem, with 35 (65%) displaying resistance to both imipenem and meropenem. Of the 54 CRKP isolates, 24 (44%) were metallo-β-lactamases (MBL)-producing. The prevalence of the blaNDM gene among CKCP and MBL-producing isolates was 20% (n = 11) and 44% (n = 24), respectively. The blaVIM and blaIMP genes were not detected in any of the isolates. Twenty-six CRKP isolates (48%) were recovered from ICUs. PFGE analysis of CRKP isolates revealed 20 clusters, with cluster S being the most prevalent, comprising 24% of the total (n = 13). Conclusion: Our study reveals a concerning prevalence of carbapenem resistance in K. pneumoniae isolates. Specifically, the detection of the blaNDM gene in 20% of CRKP isolates, with a significant proportion (82%) observed in isolated CRKP from the ICUs and emergency departments, underscores the potential clonal expansion of these resistant strains within these critical hospital wards. [ABSTRACT FROM AUTHOR]

Acinetobacter baumannii was reported as a frequent pathogen leading to outbreaks of multidrug-resistant organisms both in the intensive care unit (ICU) and in non-ICU units during the coronavirus disease in 2019 (COVID-19). In this study we aimed to examine the phenotypic and molecular characteristics of clinical isolates of carbapenem-resistant A. baumannii (CrAb) obtained from Siirt Training Hospital in Siirt, Türkiye, during the Covid-19 pandemic. In our study, 31.6% of the patients whose culture was taken were Covid-19 positive. Of the 57 CrAb strains tested for antibiotic resistance, 52 (91.2%) showed extensive-drug resistance (XDR), 4 (7%) multi-drug resistance (MDR), and 1 (1.8%) pan-drug resistance (PDR). According to 16 S rRNA analysis, the sequences of the CrAb strains used in our study were 99–100% similar to the 16 S rRNA genes of the A. baumannii strains registered in GenBank. The most frequently detected carbapenem resistance gene in the species in our study was the OXA51 gene (85.7%). It's interesting to note that the blaNDM gene, which has a direct connection to the Indian Subcontinent and has recently been observed in the Middle East but has been rarely detected in Türkiye, was discovered in our study at a high rate. We think that this situation is caused by migration from the Middle East due to war in recent years. Additionally, we believe that horizontal gene transfer between bacteria is the cause of the high frequency of the blaVIM gene, whose source is primarily Pseudomonas species, in A. baumannii species in our study. [ABSTRACT FROM AUTHOR]

Abstract Klebsiella pneumoniae (K. pneumoniae) is a major cause of healthcare-associated infections and plays a prominent role in the widespread antibiotic resistance crisis. Accurate identification of carbapenemases is essential to facilitate effective antibiotic treatment and reduce transmission of K. pneumoniae. This study aimed to detect carbapenemase production in carbapenem-resistant K. pneumoniae strains using phenotypic and genotypic methods. A total of 67 carbapenem-resistant K. pneumoniae strains obtained from various clinical samples were utilized for identification and antimicrobial susceptibility by the Vitek 2 Compact system (Biomerieux, France). Carbapenemase production was determined by using the Polymerase chain reaction, Blue-carba test (BCT) and Carbapenem inactivation method (CIM). Out of the isolates, 59 (88.1%) were positive bla OXA-48, 16 (23.9%) bla IMP, and five (7.5%) were positive bla NDM. No bla KPC genes were detected. The CIM identified 62 (92.5%), BCT identified 63 (94%) of PCR-positive isolates. The sensitivity and specificity of the BCT and the CIM were determined to be 96.7%, 40%, and 96.7%, 25% respectively. The bla OXA-48 gene was found to be the most prevalent in K. pneumoniae isolates. Early identification of carbapenem resistance plays a vital role in designing effective infection control strategies and mitigating the emergence and transmission of carbapenem resistance, thus reducing healthcare-associated infections.

Background: Multi-Drug-Resistant Klebsiella pneumoniae (MDR K. pneumoniae) is considered as an important opportunistic pathogen, which causes life threatening infections. K. pneumoniae is known to causes life-threatening infections. Objective: The objective of this study is to detect some β-lactamase genes inKlebsiella pneumoniae. Methods: Thirty-five K. pneumoniae isolates were obtained from some hospitals in Baghdad City between October 2022 and February 2023. The identification of K. pneumoniae isolates was done phenotypically by the automated VITEK II system and genotypically by amplification of the rpob gene. The antibiotic susceptibility and detection of some β-lactamase genes were tested for all isolates. Results: The results showed that the K. pneumoniae isolates were resistant to most antibiotics used. A high percentage of K. pneumoniae isolates were resistant to cefixime, cefpodoxime, norfloxacin and doxycycline as 100% followed by ceftriaxone, ceftazidime, ticarcillin/clavulanate, ticarcillin, ceftazidime, tobramycin, and moxifloxacin (97.2%, 91.7%, 91.7%, 94.4%, 94.4%, and 94.4%, respectively). Furthermore, approximately 94.4% of the isolates were MDR. In addition, the molecular methods only detected the blaNDM and blaT EM genes as 33.3% and 75.6% of in the K. pneumoniae isolates, respectively, while the blaV IM, blaCTX−M, and blaKP C genes were not observed in K. pneumoniae isolates. Conclusions: β-lactam antibiotics, including carbapenems, are widely used to treat bacterial infections; however, an increase in antibiotic resistance due to β-lactamases limits the effectiveness of these antibiotics. Therefore, alternative treatment methods are required to control these resistant isolates.

Background: The occurrence of carbapenem-resistant bacterial infections has increased significantly over the years with Gram-negative bacteria exhibiting the broadest resistance range. In this study we aimed to investigate the genomic characteristics of clinical carbapenem-resistant Enterobacterales (CRE). Methods: Seventeen representative multi-drug resistant (MDR) isolates from a hospital setting showing high level of resistance to carbapenems (ertapenem, meropenem and imipenem) were chosen for further characterization through whole-genome sequencing. Resistance mechanisms and transferability of plasmids carrying carbapenemase-encoding genes were also determined in silico and through conjugative mating assays. Results: We detected 18 different β-lactamases, including four carbapenemases (blaNDM-1, blaNDM-5, blaNDM-7, blaOXA-48) on plasmids with different Inc groups. The combined results from PBRT and in silico replicon typing revealed 20 different replicons linked to plasmids ranging in size between 80 and 200 kb. The most prevalent Inc groups were IncFIB(K) and IncM. OXA-48, detected on 76-kb IncM1 conjugable plasmid, was the most common carbapenemase. We also detected other conjugative plasmids with different carbapenemases confirming the role of horizontal gene transfer in the dissemination of antimicrobial resistance genes. Conclusion: Our findings verified the continuing spread of carbapenemases in Enterobacterales and revealed the types of mobile elements circulating in a hospital setting and contributing to the spread of resistance determinants. The occurrence and transmission of plasmids carrying carbapenemase-encoding genes call for strengthening active surveillance and prevention efforts to control antimicrobial resistance dissemination in healthcare settings.

Jinzhu Huang,* Jinxin Zhao,* Miao Yi, Yaling Yuan, Peiwen Xia, Bingxue Yang, Jiajia Liao, Zijun Dang, Yun Xia* Department of Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yun Xia, Department of Laboratory Medicine, The First Affiliated Hospital of Chongqing Medical University, No. 1 Youyi Road, Yuzhong District, Chongqing, 400016, People’s Republic of China, Tel +86-13668043942, Fax +86-23-89012513, Email xiayun12cn@aliyun.comPurpose: This research aims to profile ten novel strains of carbapenem-resistant Enterobacteriaceae (CRE) co-carrying blaKPC and blaNDM.Methods: Clinical CRE strains, along with corresponding medical records, were gathered. To ascertain the susceptibility of the strains to antibiotics, antimicrobial susceptibility tests were conducted. To validate the transferability and cost of fitness of plasmids, conjugation experiments and growth curves were employed. For determining the similarity between different strains, ERIC-PCR was utilised. Meanwhile, whole genome sequencing (WGS) was performed to characterise the features of plasmids and their evolutionary characteristics.Results: During the course of this research, ten clinical CRE strains co-carrying blaKPC and blaNDM were gathered. It was discovered that five out of these ten strains exhibited resistance to tigecycline. A closer examination of the mechanisms underlying tigecycline resistance revealed that tmexCD 1-toprJ 1, blaKPC-2, and blaNDM-1 existed concurrently within a single Citrobacter freundii strain (CF10). This strain, with a minimum inhibitory concentration (MIC) of 32 mg/L to tigecycline, was obtained from a sepsis patient. Furthermore, an investigation of genome evolution implied that CF10 belonged to a novel ST type 696, which lacked analogous strains. Aligning plasmids exposed that similar plasmids all had less than 70% coverage when compared to pCF10-tmexCD1, pCF10-KPC, and pCF10-NDM. It was also found that tmexCD 1-toprJ 1, blaKPC-2, and blaNDM-1 were transferred by Tn 5393, IS 5, and Tn 6296, respectively.Conclusion: This research presents the first report of coexistence of tmexCD 1-toprJ 1, blaKPC-2, and blaNDM-1 in a carbapenem and tigecycline-resistant C. freundii strain, CF10.Importance: Tigecycline is considered a “last resort” antibiotic for treating CRE infections. The ongoing evolution of resistance mechanisms to both carbapenem and tigecycline presents an alarming situation. Moreover, the repeated reporting of both these resistance mechanisms within a single strain poses a significant risk to public health. The research revealed that the genes tmexCD 1-toprJ 1, blaKPC-2, and blaNDM-1, which cause carbapenem and tigecycline-resistance in the same strain, were located on mobile elements, suggesting a potential for horizontal transmission to other Gram-negative bacteria. The emergence of such a multi-resistant strain within hospitals should raise significant concern due to the scarcity of effective antimicrobial treatments for these “superbugs”.Keywords: blaKPC, blaNDM, carbapenem-resistantEnterobacteriaceae, tigecycline-resistance, tmexCD 1-toprJ 1

Pseudomonas aeruginosa, a gram-negative bacterium, is notorious for its innate resistance to many antibiotics. Carbapenems are broad-spectrum antibiotics often used to treat severe P. aeruginosa infections. However, the emergence and proliferation of carbapenem-resistant P. aeruginosa (CRPA) strains have become a grave global health concern. This study examined the co-occurrence of four major carbapenemase genes, namely blaNDM, blaVIM, blaKPC, and blaOXA-48, in clinical isolates of P. aeruginosa. Using standard microbiological methods,150 P. aeruginosa clinical isolates were collected and identified, and antimicrobial susceptibility testing was conducted following Clinical and Laboratory Standards Institute guidelines. Polymerase chain reaction (PCR) with gene-specific primers was used to detect the presence of carbapenemase genes. Among the 150 P. aeruginosa clinical isolates, 62(41.3%) were found to be carbapenem-resistant. The most detected carbapenemase genes were blaKPC (49%), blaNDM (31%), blaOXA-48 (22%), and blaVIM (9%). Notably 13(12.9%) isolates carried two carbapenemase genes. The combination of blaKPC and blaNDM genes was found in eight isolates, two isolates carried blaKPC and blaVIM, and three isolates carried blaOXA-48 and blaNDM. Four isolates (6.5%) harbored three carbapenemase genes. Co-occurrence of blaNDM, blaVIM, blaKPC, and blaOXA-48 was observed in four isolates (2.8%). Our findings highlight the alarming prevalence of carbapenemase genes, particularly blaNDM and blaKPC, in clinical isolates of P. aeruginosa. The co-occurrence of multiple carbapenemase genes in the same isolate raises concerns about the potential for horizontal gene transfer and dissemination of multidrug-resistant P. aeruginosa strains in clinical settings. Further research is needed to elucidate the molecular mechanisms underlying the co-occurrence of carbapenemase genes and their impact on the clinical outcomes of P. aeruginosa infections. Urgent measures, such as enhanced surveillance, infection control protocols, and antibiotic stewardship programs, are imperative to combat the emergence and spread of CRPA strains.

ABSTRACT: Objectives: Presence and dissemination of plasmid-mediated AmpC genes (pAmpCs) have made bacteria cephalosporin-resistant and assessment of their prevalence and diversity is essential. Coexistence of pAmpCs with New Delhi metallo-β-lactamase (blaNDM) has facilitated their spread and NDM interferes with correct pAmpC phenotypic identification. Methods: Assessment of pAmpCs in different species and sequence types (STs), co-transmission with blaNDM and phenotypic detection were analysed among Klebsiella pneumoniae (n = 256) and Escherichia coli (n = 92) isolated from septicaemic neonates over 13 years. Results: pAmpCs were present in 9% (30/348) of strains, 5% in K. pneumoniae and 18% in E. coli. pAmpC genes (blaCMY and blaDHA) were detected, blaCMY-42 and blaDHA-1 variants being predominant. Strains were resistant to most antimicrobials tested. blaCMY and blaDHA were dominant among E. coli (14/17) and K. pneumoniae (9/13), respectively. pAmpC-bearing strains belonged to diverse STs, including epidemic K. pneumoniae ST11 and ST147. Some strains co-harboured carbapenemase genes, blaNDM (17/30) and blaOXA-48 (5/30). In 40% (12/30) of strains, pAmpC genes were transferred by conjugation, of which 8/12 exhibited co-transfer with blaNDM. pAmpCs were frequently found in replicons as follows: blaDHA-1 with IncHIB-M, blaCMY-4 with IncA/C, blaCMY-6 with IncA/C, and blaCMY-42 with IncFII. The combination disk-diffusion test correctly detected pAmpC in 77% (23/30) of pAmpC-bearing strains. However, correct detection of pAmpC was higher in strains that did not harbour blaNDM vs. those with blaNDM (85% vs. 71%). Conclusion: Presence of pAmpCs along with carbapenemases, linkage with multiple STs, and replicon types indicated their potential for spread. pAmpCs can go undetected in the presence of blaNDM; hence, regular surveillance is required.

Relevance. Currently, studies of the prevalence of antibiotic resistance and its genetic characteristics are focused primarily on the adult population, although infection with multiple drug infection has been registered as etiological agents of a general infection in obstetric and gynecological and pediatric institutions. The study of the prevalence of genetic determinants of antibiotic resistance is an important area of scientific research.Aim. To analyze the results of the studies carried out to identify the genetic determinants of antibiotic resistance of enterobacteria isolated during microbiological monitoring in the perinatal center.Materials and methods. The genetic profile of antibiotic resistance was studied in ESBL-producing strains isolated from 45 women and 35 children examined at the departments of the Federal State Budgetary Institution «NII OMM» of the Ministry of Health of Russia. To determine the determinants of antibiotic resistance, 80 non-duplicate strains of 7 species of the Enterobacteriaceae family were studied. DNA of bacterial cells was isolated from a daily culture of microorganisms using the PROBA-NK kit, detection of the tem, ctx-M-1, shv genes; oxa-40-like, oxa-48-like, oxa-23-like, oxa-51-like, imp, kpc, ges, ndm, vim were carried out using the diagnostic kit «BacResista GLA» on the detecting amplifier DT-48 (DNA -technology, Russia). To assess the statistical significance of differences in the frequency of occurrence of genes, Pearson's c2 test with Yates' correction was used.Results and discussion. When analyzing the results of studies on the molecular genetic detection of antibiotic resistance determinants, which we conducted in 2022, it was found that 8 genovariants were found in bacterial strains isolated from patients of the departments of the Research Institute of OMM in Yekaterinburg, providing resistance to beta-lactam antibiotics. The dominant genome, as in 2021, remains blaCTX-M-1, found in 29 cases. The blaTEM gene was identified both in association with other genes and as a single variant in Escherichiae coli and Klebsiella pneumoniae strains. Of the eight strains of K. pneumoniae, 4 were found to have three antibiotic resistance genes blaCTX-M, blaTEM, blaSHV, strains with a genetic profile of blaCTX-M, blaTEM, blaSHV, blaNDM were isolated once; and blaTEM, blaSHV, blaKPC. In one strain of K. pneumoniae, phenotypically showing resistance to AB, no genetic determinants of AB resistance were found. In addition to resistance to beta-lactam antibiotics, the strains demonstrate resistance to such groups of antibacterial drugs as fluoroquinolones, phosphonic acid derivatives (fosfomycin), and aminoglycosides. The data obtained indicate that the intestines of newborns during their stay at the stationary stage of nursing in some cases are colonized by strains of enterobacteria with multidrug resistance. Consequently, children are a reservoir of resistant microorganisms and can be sources of pathogens of infectious diseases in families and children's organized groups.

Background: In resource-constrained settings, limited antibiotic options make treating carbapenem-resistant bacterial infections difficult for healthcare providers. This study aimed to assess carbapenemase expression in Gramnegative bacteria isolated from clinical samples in Jimma, Ethiopia. Methods: A cross-sectional study was conducted to assess carbapenemase expression in Gram-negative bacteria isolated from patients attending Jimma Medical Center. Totally, 846 Gram-negative bacteria were isolated and identified using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Phenotypic antibiotic resistance patterns were determined using the Kirby-Bauer disk diffusion method and Etest strips. Extended-spectrum β-lactamase phenotype was determined using MAST disks, and carbapenemases were characterized using multiplex polymerase chain reactions (PCR). Results: Among the isolates, 19% (157/846) showed phenotypic resistance to carbapenem antibiotics. PCR analysis revealed that at least one carbapenemase gene was detected in 69% (107/155) of these strains. The most frequently detected acquired genes were blaNDM in 35% (37/107), blaVIM in 24% (26/107), and blaKPC42 in 13% (14/107) of the isolates. Coexistence of two or more acquired genes was observed in 31% (33/107) of the isolates. The most common coexisting acquired genes were blaNDM + blaOXA-23, detected in 24% (8/33) of these isolates. No carbapenemase-encoding genes could be detected in 31% (48/155) of carbapenem-resistant isolates, with P. aeruginosa accounting for 85% (41/48) thereof. Conclusion: This study revealed high and incremental rates of carbapenemresistant bacteria in clinical samples with various carbapenemase-encoding genes. This imposes a severe challenge to effective patient care in the context of already limited treatment options against Gram-negative bacterial infections in resource-constrained settings. [ABSTRACT FROM AUTHOR]

Carbapenem-resistant Enterobacterales (CRE) is a global concern. This study investigated the prevalence of fecal colonization carriage and clonal dissemination of CRE among population in four provinces of China. A total of 685 stool samples were collected from four provinces in China. Among these samples, 141 and 544 were obtained from healthy and hospitalized individuals, respectively. The overall fecal carriage rate was 9.6% (65/685) with 4.26% (95% CI: 0.9-7.6) in healthy individuals and 10.84% (95% CI: 8.2-13.5) in hospitalized patients. The highest prevalence was in Henan province (18.35%, 95% CI: 9%-18.7%). Sixty-six CRE isolates were identified in Escherichia coli (56.06%, 37/66), Klebsiella (15.15%, 10/66), Citrobacter (13.63%, 9/66), Enterobacter (12.12%, 8/66), and Atlantibacter (1.51%, 1/66). All CRE strains carried carbapenemase genes and multiple antibiotics resistance genes, blaNDM-5 (77.27%, 51/66) was the most common carbapenemase gene, followed by blaNDM-1 (19.69%, 13/66). Antibiotic resistance genes, including blaIMP-4, and the colistin colistin resistance (mcr-1) gene were also identified. All CRE isolates belonged to different sequence types (STs). ST206 (36.84%, 14/38) in E. coli and ST2270 (60%, 6/10) in Klebsiella were significantly dominant clones. The results indicated the prevalence of CRE fecal carriage among adults of China, mostly blaNDM-producing E coli, which pose significant challenges for clinical management. Screening for CRE colonization is necessary to control infection. [ABSTRACT FROM AUTHOR]

Carbapenem is one of the few available drugs to treat multidrug-resistance Gram-negative bacteria infections. Recently, the plasmid-mediated spread of the carbapenem resistance gene blaNDM poses a significant threat to public health, requiring global monitoring and surveillance. Here, we used both short-read (n = 2461) and long-read (n = 546) sequencing data to characterize the global distribution of blaNDM. We analyzed the replicon type of blaNDM-positive plasmids and found that the dominant plasmid type was different in diverse geographical locations. Although blaNDM gene has been transferred across diverse countries, its genetic backgrounds are highly conserved, and the mobile genetic element ISAba125, IS5, and IS26 may play an important role in the mobilization of blaNDM. A significant association was observed between host origin and gene presence/deletion variation on IncX3 plasmid, which may be a key factor in the bacterial adaption to diverse hosts. In this study, we analyzed the diversity, distribution and transmission of blaNDM-positive plasmids from a global perspective, and emphasize the importance of plasmid analysis for understanding the evolution and adaptation of blaNDM-positive plasmids and their co-evolution with bacterial genomes (resistome). [ABSTRACT FROM AUTHOR]

The study aims to detect the presence of carbapenems genes and the prevalence of antibiotic-resistant E. coli in the Tigris River. Samples were collected from three sites of the Tigris River: S1Adhamiya, S2 Medical city hospital, and S3 Abu Nuwas. It diagnosed 40 isolates of E. coli out of 67 isolates of bacteria by Vitek2. The antibiotic sensitivity was determined by the disk diffusion method. E.coli isolates were tested against 7 antibiotics these belonged to β-lactam, Carbapenem. Also, the resistance genes )blaVIM and blaNDM) detected for these isolates of E. coli. The results appeared resistance of E.coli against AMC 82.5%, PRL 62.5%, AM 55%, and moderate resistance against CRO 45% whereas little resistance against ATM 27.5% and carbapenem including IPM 5%and MRP 5%. Also, the results of resistance genes have appeared in two isolates that have the resistance gene blaVIM (5%) and one isolate has blaNDM genes (2.5%). These isolates appeared resistant to β-lactam group antibiotics and little resistance to E. coli to carpamenes antibiotics (IMP, MER). [ABSTRACT FROM AUTHOR]

The occurrence of carbapenem-resistant bacterial infections has increased significantly over the years with Gram-negative bacteria exhibiting the broadest resistance range. In this study we aimed to investigate the genomic characteristics of clinical carbapenem-resistant Enterobacterales (CRE). Seventeen representative multi-drug resistant (MDR) isolates from a hospital setting showing high level of resistance to carbapenems (ertapenem, meropenem and imipenem) were chosen for further characterization through whole-genome sequencing. Resistance mechanisms and transferability of plasmids carrying carbapenemase-encoding genes were also determined in silico and through conjugative mating assays. We detected 18 different β-lactamases, including four carbapenemases (bla NDM-1 , bla NDM-5 , bla NDM-7 , bla OXA-48) on plasmids with different Inc groups. The combined results from PBRT and in silico replicon typing revealed 20 different replicons linked to plasmids ranging in size between 80 and 200 kb. The most prevalent Inc groups were IncFIB(K) and IncM. OXA-48, detected on 76-kb IncM1 conjugable plasmid, was the most common carbapenemase. We also detected other conjugative plasmids with different carbapenemases confirming the role of horizontal gene transfer in the dissemination of antimicrobial resistance genes. Our findings verified the continuing spread of carbapenemases in Enterobacterales and revealed the types of mobile elements circulating in a hospital setting and contributing to the spread of resistance determinants. The occurrence and transmission of plasmids carrying carbapenemase-encoding genes call for strengthening active surveillance and prevention efforts to control antimicrobial resistance dissemination in healthcare settings. [ABSTRACT FROM AUTHOR]

After an increase in carbapenem-resistant Klebsiella pneumoniae (CRKP) bloodstream infections and associated deaths in the neonatal unit of a South Africa hospital, we conducted an outbreak investigation during October 2019–February 2020 and cross-sectional follow-up during March 2020–May 2021. We used genomic and epidemiologic data to reconstruct transmission networks of outbreak-related clones. We documented 31 cases of culture-confirmed CRKP infection and 14 deaths. Two outbreak-related clones (blaNDM-1 sequence type [ST] 152 [n = 16] and blaOXA-181 ST307 [n = 6]) cocirculated. The major clone blaNDM-1 ST152 accounted for 9/14 (64%) deaths. Transmission network analysis identified possible index cases of blaOXA-181 ST307 in October 2019 and blaNDM-1 ST152 in November 2019. During the follow-up period, 11 new cases of CRKP infection were diagnosed; we did not perform genomic analysis. Sustained infection prevention and control measures, adequate staffing, adhering to bed occupancy limits, and antimicrobial stewardship are key interventions to control such outbreaks.

With the increasing burden of carbapenem-resistant Klebsiella pneumoniae (CR-Kp), including high rates of healthcare-associated infections, treatment failure, and mortality, a good therapeutic strategy for attacking this multi-resistant pathogen is one of the main goals in current medical practice and necessitates the use of novel antibiotics or new drug combinations. Objectives: We reviewed the clinical and microbiological outcomes of seven patients treated at the “Agrippa Ionescu” Clinical Emergency Hospital between October 2023 and January 2024, aiming to demonstrate the synergistic activity of the ceftazidime–avibactam (C/A) plus aztreonam (ATM) combination against the co-producers of blaNDM + blaOXA-48-like CR-Kp. Material and Methods: Seven CR-Kp with blaNDM and blaOXA-48 as resistance mechanisms were tested. Seven patients treated with C/A + ATM were included. The synergistic activity of C/A + ATM was proven through double-disk diffusion in all seven isolates. Resistance mechanisms like KPC, VIM, OXA-48, NDM, IMP, and CTX-M were assessed through immunochromatography. Results: With a mean of nine days of treatment with the synergistic combination C/A + ATM, all patients achieved clinical recovery, and five achieved microbiological recovery. Conclusions: With the emerging co-occurrence of blaOXA-48 and blaNDM among Kp in Romania, the combination of C/A and ATM could be a promising therapeutic option.

BackgroundIn resource-constrained settings, limited antibiotic options make treating carbapenem-resistant bacterial infections difficult for healthcare providers. This study aimed to assess carbapenemase expression in Gram-negative bacteria isolated from clinical samples in Jimma, Ethiopia.MethodsA cross-sectional study was conducted to assess carbapenemase expression in Gram-negative bacteria isolated from patients attending Jimma Medical Center. Totally, 846 Gram-negative bacteria were isolated and identified using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Phenotypic antibiotic resistance patterns were determined using the Kirby-Bauer disk diffusion method and Etest strips. Extended-spectrum β-lactamase phenotype was determined using MAST disks, and carbapenemases were characterized using multiplex polymerase chain reactions (PCR).ResultsAmong the isolates, 19% (157/846) showed phenotypic resistance to carbapenem antibiotics. PCR analysis revealed that at least one carbapenemase gene was detected in 69% (107/155) of these strains. The most frequently detected acquired genes were blaNDM in 35% (37/107), blaVIM in 24% (26/107), and blaKPC42 in 13% (14/107) of the isolates. Coexistence of two or more acquired genes was observed in 31% (33/107) of the isolates. The most common coexisting acquired genes were blaNDM + blaOXA-23, detected in 24% (8/33) of these isolates. No carbapenemase-encoding genes could be detected in 31% (48/155) of carbapenem-resistant isolates, with P. aeruginosa accounting for 85% (41/48) thereof.ConclusionThis study revealed high and incremental rates of carbapenem-resistant bacteria in clinical samples with various carbapenemase-encoding genes. This imposes a severe challenge to effective patient care in the context of already limited treatment options against Gram-negative bacterial infections in resource-constrained settings.

Epidemiological characteristics and molecular features of carbapenem-resistant Enterobacter (CR-Ent) species remain unclear in China. In this study, we performed a genomic study on 92 isolates from Enterobacter-caused infections from a multicenter study in China. Whole genome sequencing (WGS) was used to determine the genome sequence of 92 non-duplicated CR-Ent strains collected from multiple tertiary health centres. The precise species of Enterobacter strains were identified by average nucleotide identity (ANI) and in silico DNA–DNA hybridization (isDDH). Molecular features of high-risk CR-Ent sequence type (ST) lineages and carbapenemase-encoding plasmids were determined. The result revealed that the most common human-source CR-Ent species in China was E. xiangfangensis (66/92, 71.93%), and the proportion of carbapenemase-producing Enterobacter (CP-Ent) in CR-Ent was high (72/92, 78.26%) in comparison to other global regions. Furthermore, ST171 and ST116 E. xiangfangensis were the major lineages of CP-Ent strains, and ST171 E. xiangfangensis was more likely to cause infections in older patients. Genomic analysis also highlighted the likelihood of intra-hospital/inter-hospital clonal transmission of ST171 and ST116 E. xiangfangensis. In addition, the blaNDM-harbouring IncX3-type plasmid was identified as the prevalent carbapenemase-encoding plasmid carried by CR-Ent strains, and was experimentally confirmed to be able to self-transfer with high frequency. This study detailed the genomic and clinical characteristics of CR-Ent in China in the form of multicenter for the first time. The high risk of carbapenemase-producing ST171 and ST116 E. xiangfangensis, and the blaNDM-harbouring IncX3-type plasmid were detected and emphasized.

The present study determined the effect of untreated wastewater on the prevalence of carbapenem resistance in Acinetobacter baumannii (CRAB) in both the wastewater and the receiving river water surrounding Cuttack City. Physiochemical parameters, heavy metal contamination factors (CF), contamination degree (CD), pollution load index (PLI), and microbiological content (total coliform, fecal form, and CRAB) were analyzed in two untreated urban wastewater and three in receiving river water (upstream, catchment, and downstream). The high BOD, CF, CD, and PLI in urban wastewater, river catchment, and downstream revealed intense anthropogenic activity. After blaOXA-51 detection and clonal analysis by ERIC-PCR, a total of 73 CRAB were selected for further analysis. All the CRAB isolates were 100% resistant to penicillin, β-lactam/β-lactamase inhibitor, cephalosporin, and carbapenem groups of antibiotics. The antibiotic profile showed 73.97% CRAB isolates assigned as extremely drug resistant. Detection of carbapenemase (blaNDM and blaOXA-48) and co-harboring ESBL (blaTEM) genes, the highest at the river, reflects direct disposal of biomedical wastes. MAR index (> 0.2) and virulence index (> 0.5) in 59 isolates were classified as a high threat posing a severe human risk. A similar ERIC pattern between the isolates from two different locations (catchment and downstream) indicates their dissemination downstream through river water flow. The extraordinary ability of resistant A. baumannii to thrive in the river makes it unfit for household activities and poses a public health threat. Therefore, frequent monitoring of resistance levels in water could help direct antibiotic use and resistance management. [ABSTRACT FROM AUTHOR]

Tian Jiang,1,* Guoli Li,2,* Linyao Huang,1 Ding Ding,1 Zhi Ruan,2 Jianxin Yan1 1Department of Clinical Laboratory, The Affiliated Wenling Hospital, Wenzhou Medical University, Wenling, People’s Republic of China; 2Department of Clinical Laboratory, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China*These authors contributed equally to this workCorrespondence: Zhi Ruan; Jianxin Yan, Email r_z@zju.edu.cn; yjx6206095@163.comObjective: Klebsiella michiganensis is an emerging hospital-acquired bacterial pathogen. However, there is a dearth of knowledge on the antimicrobial resistance and transmission of K. michiganensis. Here, we characterized the microbiological and genomic features of a carbapenem-resistant K. michiganensis strain harboring the blaNDM-1 gene in China.Methods: K. michiganensis strain 2563 was recovered from the sputum sample of a hospitalized patient with pulmonary infection. Whole-genome sequencing of K. michiganensis strain 2563 was conducted using both the short-read Illumina and long-read MinION platforms to thoroughly characterize the genetic context of blaNDM-carrying plasmid in K. michiganensis 2563. Furthermore, BacWGSTdb server was utilized to perform in silico multilocus sequence typing (MLST), identify antimicrobial resistance genes, and conduct genomic epidemiological analyses of the closely related isolates deposited in the public database.Results: K. michiganensis 2563 was resistant to piperacillin, aztreonam, meropenem, imipenem, amoxicillin-clavulanic acid, ampicillin, cefotaxime, cefazolin, ampicillin/sulbactam, cefepime, piperacillin-tazobactam, and ceftazidime. It belonged to sequence type (ST) 43, and the blaNDM-1 gene was found to be located on the plasmid p2563_NDM (54,035 bp). This plasmid showed remarkable similarity to other blaNDM-1-encoding plasmids found in various Enterobacterium species in the public database. The occurrence of global ST43 K. michiganensis was primarily sporadic, and the closest relative of K. michiganensis 2563 was another ST43 isolate 12,084 recovered from China in 2013, which differed by 171 SNPs.Conclusion: Our study reports the genome characteristics of a carbapenem-resistant K. michiganensis strain carrying the blaNDM-1 gene in China, highlighting the need for ongoing surveillance of this pathogen in clinical settings.Keywords: whole-genome sequencing, Klebsiella michiganensis, blaNDM, multidrug-resistant, phylogenetics

Introduction: The healthcare burden of carbapenem-resistant Klebsiella pneumoniae (K. pneumoniae) infections is growing. The newly developed beta-lactam/beta-lactamase inhibitor combination, ceftazidime-avibactam, shows promise in the treatment of such infections. We aimed to explore the in vitro efficacy of ceftazidime-avibactam against carbapenem-resistant K. pneumoniae isolates carrying the blaOXA-48 gene. Materials and Methods: The isolates were identified using MALDI-TOF MS (Brucker, USA). The isolates that were non-susceptible to imipenem, meropenem, or ertapenem by the disk diffusion method using the European Committee of Antimicrobial Susceptibility Testing (EUCAST) breakpoints were screenes. Minimum inhibitory concentration (MIC) values were determined via broth microdilution according to the EUCAST criteria. A time-kill study was performed according to Clinical and Laboratory Standards Institute guidelines. Beta-lactamase genes were screened for using polymerase chain reaction with previously published primers. Results: A total of 129 K. pneumoniae isolated between April 2011 and February 2021 were studied. Of these, 98, 23, and eight isolates carried the blaOXA-48, blaNDM, and blaOXA-48 with blaNDM genes, respectively. All isolates carrying the blaNDM gene were resistant to ceftazidime-avibactam. Approximately 79.6% of the blaOXA-48-positive isolates were susceptible to ceftazidime-avibactam. The time-kill study for ceftazidime-avibactam was performed with one blaOXA-48-positive isolate (MIC, 4 mg/l). Ceftazidime-avibactam time-kill kinetics were evaluated in multiples of MIC. There was a decrease of ≥3-log10 in CFU/ml count at a concentration of 8, 16, and 32 MIC at 6 hours. The minimum bactericidal concentration was 8 mg/l. Conclusion: Ceftazidime-avibactam is an important treatment alternative alternative for blaOXA-48 positive carbapenem-resistant K. pneumoniae infections. The most rational approach to the treatment of carbapenem-resistant K. pneumoniae infections appears to be the initiatiion of targeted therapy according to culture antibiogram results or revision of the empirically initiated combination or monotherapy as early as possible according to culture antibiogram results.

The present study was conducted to study the influence of imipenem and meropenem at subinhibitory concentration on the transcriptional response of Las/Rhl quorum-sensing systems in isolates of Pseudomonas aeruginosa. In the present study, six representative carbapenem nonsusceptible clinical isolates of P. aeruginosa were obtained. The agar dilution method was used to determine the minimum inhibitory concentration against imipenem and meropenem. The bacterial isolates were then cultured up to the early log phase in fresh Luria Bertani (LB) broths at 37°C with and without 2 µg mL−1 imipenem and meropenem, respectively. mRNA was then isolated from the bacterial isolates and was immediately reverse-transcribed to cDNA. The relative quantity of the expression of the lasI, lasR, rhlI, and rhlR genes was assessed by quantitative real-time Polymerase Chain Reaction (PCR) using the ΔΔCt method. The transcriptional response of the lasI and lasR genes was upregulated at subinhibitory concentration of meropenem. In contrast, the transcriptional response of the lasI, lasR, and rhlR genes was downregulated at subinhibitory concentration of imipenem as compared to the expression in untreated isolates. The data obtained in the current study showcased the ability of imipenem and meropenem to influence the response of the quorum-sensing genes at subinhibitory concentration. [ABSTRACT FROM AUTHOR]

Background: All b-lactamase enzymes, or carbapenemases, are able to hydrolyzing the beta-lactam antibiotics. The ability of Klebsiella pneumoniae to produce carbapenemases is the primary cause of carbapenem resistance in this organism. Objective: To define the prevalence as well as characterization of carbapenem resistance with genes coding for the carbapenemase in carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates that was taken from patients in the intensive care units (ICUs) of Zagazig University Hospitals. Patients and Methods: In a cross-sectional study we included patients who were diagnosed with K. pneumoniae infections from different ICUs of Zagazig University Hospitals, which are referral hospitals serving many patients in eastern Egypt. Results: In this study 120 out of the 190 participants who had a confirmed K. pneumoniae infection were found to have CRKP infections. The XpertCarba-R assay was used to test the isolates for the presence of blaNDM, blaIMP, blaVIM, blaKPC, and blaOXA-48. The blaNDM (60%), blaOXA-48 (47.6%), and blaKPC (8.4%) genes were the most common. None of the isolates had either blaVIM or blaIMP present. Conclusion: These current data indicate spread of CRKP isolates in our institution poses a serious health threat. Limiting transmission depends on early detection of isolates that are resistant to carbapenem. In order to prevent the spread of the CRKP, it is necessary to pay more attention to rationalizing the use of antibiotics and strengthening the application of infection control precautions, such as hand hygiene, patient isolation, environmental cleaning and antibiotics stewardship programs. [ABSTRACT FROM AUTHOR]

Background: The rapid emergence of carbapenem resistant Acinetobacter baumannii (CRAB) has resulted in an alarming situation worldwide. Realizing the dearth of literature on susceptibility of CRAB in genetic context in the developing region, this study was performed to determine the susceptibility profile against standard drugs/combinations and the association of in-vitro drug synergy with the prevalent molecular determinants. Methods and findings: A total of 356 clinical isolates of A. baumannii were studied. Confirmation of the isolates was done by amplifying recA and ITS region genes. Susceptibility against standard drugs was tested by Kirby Bauer disc diffusion. Minimum inhibitory concentration (MIC), MIC50 and MIC90 values against imipenem, meropenem, doripenem, ampicillin/sulbactam, minocycline, amikacin, polymyxin B, colistin and tigecycline was tested as per guidelines. Genes encoding enzymes classes A (blaGES, blaIMI/NMC-A, blaSME, blaKPC), B (blaIMP, blaVIM, blaNDM) and D (blaOXA-51, blaOXA-23 and blaOXA-58) were detected by multiplex polymerase chain reaction. Synergy against meropenem-sulbactam and meropenem-colistin combinations was done by checkerboard MIC method. Correlation of drug synergy and carbapenemase encoding genes was statistically analyzed. Results: Of the total, resistance above 90% was noted against gentamicin, ciprofloxacin, levofloxacin, ceftazidime, cefepime, ceftriaxone, cotrimoxazole and piperacillin/tazobactam. By MIC, resistance rates from highest to lowest was seen against imipenem 89.04% (n=317), amikacin 80.33% (n=286), meropenem 79.49% (n=283), doripenem 77.80% (n=277), ampicillin/sulbactam 71.62% (n=255), tigecycline 55.61% (n=198), minocycline 14.04% (n=50), polymyxin B 10.11% (n=36), and colistin 2.52% (n=9). CRAB was 317 (89.04%), 81.46% (n=290) were multidrug resistant and 13.48% (n=48) were extensively drug resistant. All the CRAB isolates harboured blaOXA-51 gene (100%) and 94% (n=298) blaOXA-23 gene. The blaIMP gene was most prevalent 70.03% (n=222) followed by blaNDM, 59.62% (n=189). Majority (87.69%, 278) were co-producers of classes D and B carbapenemases, blaOXA-23 with blaIMP and blaNDM being the commonest. Synergy with meropenem-sulbactam and meropenem-colistin was 47% and 57% respectively. Reduced synergy (p= <0.0001) was noted for those harbouring blaOXA-51+blaOXA-23with blaNDM gene alone or co-producers. Conclusion: Presence of blaNDM gene was a significant cause of synergy loss in meropenem-sulbactam and meropenem-colistin. In blaNDM endemic regions, tigecycline, minocycline and polymyxins could be viable options against CRAB isolates with more than one carbapenemase encoding genes. [ABSTRACT FROM AUTHOR]

Objective(s): Production of metallo-β-lactamases (MBLs) is an important mechanism of resistance to carbapenems. This study aimed to detect the MBL-producing Pseudomonas aeruginosa clinical isolates and to investigate the presence of blaVIM, blaIMP, blaSPM, blaNDM, blaGIM, blaAIM, and blaSIM genes in these isolates in Bushehr, Iran. Materials and Methods: A total of 169 P. aeruginosa clinical isolates were collected from three hospitals in Bushehr. The modified carbapenem inactivation method (mCIM) was used for the phenotypic detection of carbapenemase production. A combination disk test (CDT) was performed for the phenotypic detection of MBL production. To investigate the presence of blaVIM, blaIMP, blaSPM, blaNDM, blaGIM, blaAIM, and blaSIM genes, PCR and sequencing was carried out.Results: Based on the results of mCIM, 40 (23.7%) of 169 isolates were carbapenemase producers. CDT revealed that 26 (15.4%) isolates were MBL producers. blaIMP, blaNDM, and blaVIM genes were found in 18 (69.2%), 8 (30.8%), and 1 (3.8%) of the MBL-producing isolates, respectively. Coexistence of blaIMP and blaNDM was observed in 2 (7.7%) MBL-producing isolates. Among all 169 P. aeruginosa isolates, 23 (13.6%) harbored blaNDM, 18 (10.6%) carried blaIMP, and 1 (0.6%) carried the blaVIM gene. blaSPM, blaGIM, blaAIM, and blaSIM were not found in the present study. Conclusion: blaNDM, blaIMP, and blaVIM genes were detected in this study, which could be a warning sign about the prevalence of these genes among P. aeruginosa clinical isolates in our region. Proper monitoring and detection of MBL-producing isolates are essential steps to prevent the spread of these isolates.

Carbapenem-resistant Enterobacteriaceae (CRE) poses an increasing public health threat and has limited treatment options with high associated mortality. Genotypes of carbapenemase that threaten public health (blaKPC, blaNDM, blaIMP, and blaVIM) and blaOXA-48-like genes were detected by phenotypic and molecular diagnosis, and related gene distribution patterns were investigated. Phenotypic testing using the modified Hodge test confirmed positivity in all 41 strains examined, and carbapenemase inhibitory testing using meropenem+phenyl boronic acid or meropenem+EDTA confirmed positivity in 18 and 8 strains, respectively. Polymerase chain reaction revealed the presence of amplification products in 28 strains of blaKPC, 25 strains of blaNDM, 5 strains of blaIMP, 1 strain of blaVIM, and 13 blaOXA-48-like strains. In addition, 7 strains of blaKPC+blaNDM, 1 strain of blaKPC+blaIMP, 1 strain of blaNDM+blaOXA-48-like, 1 strain of blaNDM+blaVIM, 4 strains of blaKPC+blaNDM+blaIMP, and 4 strains of blaKPC+blaNDM+blaOXA-48-like were identified. Melting curve analysis using real-time PCR was wholly consistent with PCR results. The study shows genetic identification of highly specific CRE by real-time PCR could be used to provide early diagnoses and infection control, improve surveillance, and prevent the transmission of CRE.

Background: The emergence and distribution of multidrug-resistant (MDR) and carbapenem-resistant Klebsiella pneumoniae (CRKP) has become a global health threat. Therefore, this study aimed to investigate the frequency and antibiotic resistance patterns of MDR, extensively drug-resistant (XDR), and CRKP, as well as the antibiotic resistance genes of Klebsiella pneumoniae (K. pneumoniae) isolates from patients' infectious samples from central Iran. Methods: This study examined 546 clinical samples of patients to identify K. pneumoniae. The isolates were investigated for their antibiotic resistance profile, extended-spectrum β-lactamase (ESBL), AMPC β-lactamase, carbapenemase resistance, sulfonamide, tetracycline, plasmid-mediated quinolone resistance (PMQR) along with their resistance genes, integrase, and quaternary ammonium compounds (qac) by polymerase chain reaction (PCR). Results: Out of 546 clinical samples, 121 (22.1%) cases of K. pneumoniae were identified using culture and PCR methods. The highest antibiotic resistance rates were found for ampicillin (119/121; 98.3%), cotrimoxazole (78/121; 64.4%), and cefixime, cefotaxime, ceftriaxone, and ceftazidime as a group (77/121; 63.6%). Tigecycline, colistin, and fosfomycin were the most effective antimicrobial agents with 98.4%, 96.7%, and 95.9% susceptibility, respectively. The amount of CRKP was 51 (42.1%). All CRKP isolates were MDR. The most abundant genes were blaTEM (77/77; 100%), blaCTX−M1 (76/77; 98.7%), blaSHV (76/77; 98.7%), blaCTX−M15 (73/77; 94.8%) for ESBL; blaCIT 28 (48.3%) and blaCMY−2 26 (44.8%) for AMPC β-lactamase; and blaOXA−48 46 (90.1%) and blaNDM 36 (70.5%) for carbapenemase. Among the PMQR determinants, qnrB (25/52; 48%), qnrS (19/52; 36.5%), and qnrA (11/52; 21.1%) were positive from the isolates. TetA and tetB were recognized in 25 (44.6%) and 17 (30.3%) isolates, respectively. Class 1 and 2 integrons were recognized in 97 (80.1%) and 53 (43.8%) isolates, respectively. Conclusions: Due to the high prevalence of MDR and CRKP in central Iran, tracking and immediate intervention are necessary for control and inhibition of K. pneumoniae resistant isolates. Tigecycline, colistin, and fosfomycin are the best treatment options for treatment of patients with CRKP in this geographical area. [ABSTRACT FROM AUTHOR]