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Objective:To investigate the antimicrobial resistance characteristics of carbapenem-resistant Enterobacteriaceae （CRE） isolated from outpatients with diarrhea in Shanghai， and provide support for surveillance， prevention and control of CRE. Methods:A total of 800 fecal swabs of the outpatients with diarrhea were collected from 23 sentinel hospitals for diarrhea pathogen surveillance in Shanghai from January 2018 to December 2019. The drug-resistant strains were isolated using MacConkey plates containing 1 μg/μL meropenem. The collected strains were identified preliminarily by the VITEK-2 Compact system and VITEK mass spectrometry. The minimum inhibitory concentration （MIC） of the strain was determined by the broth microdilution method. The multi-locus sequence typing （MLST） method and pulsed-field gel electrophoresis （PFGE） were used to analyze the homology of drug-resistant strains. The transferability of the resistance gene was investigated by a junction experiment. High-throughput sequencing was used to characterize the isolates. Results:Seven non-repetitive CRE isolates were multi-drug resistant carbapenem-resistant Escherichia coli （CREC） strains that produce New Delhi metallo-β-lactamase （NDM） with resistance to several commonly used antibiotics in clinical therapy. The molecular typing results showed that the CRE strains had different sequence types， and diverse PFGE patterns. The stains were all positive for blaNDM genes， including blaNDM-5 and blaNDM-13， with blaNDM-5 as the main type. The carbapenem-resistant genes could be transferred to EC600 by conjugation. Conclusion:The intestinal carbapenem-resistant strains in this study are all NDM-producing Escherichia coli. The isolates carried blaNDM and other resistance genes. The MLST analysis showed that they belonged to different cloning types. Antimicrobial resistance genes could be horizontally transferred to EC600 by conjugation.
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Objective To investigate the detection of IMP andVIM metallo-β-lactamases (MβLs)genes in clinically iso-lated gram-negative bacteria as well as bacterial resistance toβ-lactam antimicrobial agents.Methods 113 clinically isolated bacteria were performed antimicrobial susceptibility testing by Kirby-Bauer method ,drug-resistant genes IMP and VIM were detected by polymerase chain reaction (PCR),PCR products were sequenced and aligned with BLAST software. Results VIM gene was detected in 1 Pseudomonas fluorescens strain ,IMP gene was detected in 15 strains ,they were Klebsiella pneumoniae (n=6),Acinetobacter baumannii (n=3),Escherichia coli (n=2),Ralstonia picket-tii (n=1),Pseudomonas aeruginosa (n=1 ),Citrobacter amalonaticua (n=1 ),and Enterobacter cloacae (n=1 ). BLAST results showed that VIM gene was VIM-2 subtype,similarity with gene bank was 99%;all IMP genes were IMP-1 subtype,which were highly homologous ,similarity was 98%-99%.Resistant rates of IMP positive strains to ceftriaxone,cefotaxime,cefoxitin,aztreonam and imipenem were all significantly higher than negative strains (all P <0.05).Conclusion IMP genes of different strains are highly homologous,all are IMP-1 type,indi-cating that IMP genes are highly transmissible and can spread among different species of bacteria.IMP genes are related with resistance ofβ-lactam antimicrobial agents.
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Background: This was a preliminary study to test for the presence of multiple antibiotic-resistant extended spectrum β-lactamase (ESBL) producing bacteria in Malaysian urban surface waters. Although the literature review revealed several published papers on clinical ESBL isolates in Malaysia, none were found on ESBL isolates obtained from local surface waters. Methods: Isolated bacterial species were tested for resistance to cefotaxime, amoxicillin/clavulanate and aztreonam, and susceptibility to imipenem and meropenem using antibiotic susceptibility testing (AST) by disc diffusion. This served as a screening step to detect bacteria that could be potential ESBL species. 16S ribose ribonucleic acid (rRNA) polymerase chain reaction (PCR) testing with two clusters of bla (β-lactamase) gene primers was used to test for the bla genes CTX-M (Groups 1, 2, 9), OXA-1, SHV and TEM. Results: A total of 19 isolates were found, possessing at least one of the bla genes tested for. There was a relatively high occurrence of CTX-M genes (84.2%) among these, followed by TEM genes (47.4%). The isolates were identified as Enterobacteriaceae (89.5%), predominantly Escherichia coli and Klebsiella pneumoniae. Conclusion: There appears to be a high occurrence of ESBL-bacteria in local surface waters, among these being opportunistic pathogens. The persistence and spread of these species in the environment poses a threat to exposed human populations.
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Hazardous Substances , Bacteria , WaterABSTRACT
Objective To investigate β-lactamase gene and class 1 integron gene from 60 clinical Acinetobacter baumannii isolates.Methods The minimal inhibitory concentrations (MICs) for 16 antibiotics widely used were determined using the standard broth microdilution method.The β-lactamase gene,class 1 integron gene and adeB gene were determined by PCR and then sequenced.Results Fifty-three strains of the 60 A.baumanii isolates were multi-drug resistant.OXA-23 gene was detected positive in six A.baumanii isolates,which were all resistant to more than five antimicrobial agents including carbapenem and showed high resistance to many antibiotics.Thirtyeight strains earring PER-1 gene showed higher resistance to cephalosporins than those without this gene (P＜0.01).Class 1 integron gene was positive in 45 strains,which exhibited significantly higher multiple resistance than those without this gene (P＜0.01).Twenty-five strains carrying both class 1 integron and PER-1 genes had a markedly higher multiple resistance (P＜0.01),but not in resistant level,compared to the 7 strains without these two genes.Conclusion Class 1 integron and β-lactamase gene may be the causes of muhidrug-resistance of A.baumanii.The strains carrying OXA-23 gene always showed multiple and high resistance to several antibiotics,so effective measures must be taken to control the epidemic of these strains.