Objective:To assess and characterize antibiotic resistance in Acinetobacter baumannii strains recovered from 5 health-care facilities in Algiers.Methods:Antibiotic susceptibility testing was performed by agar diffusio...Objective:To assess and characterize antibiotic resistance in Acinetobacter baumannii strains recovered from 5 health-care facilities in Algiers.Methods:Antibiotic susceptibility testing was performed by agar diffusion and agar dilution methods,resistance genes were identified by PCR and sequencing,and molecular typing of isolates was carried out by enterobacterial repetitive intergenic consensus-PCR(ERIC-PCR).Results:Among 125 tested isolates,117(93.6% ) were multidrug-resistant.of which 94(75.2% ) were imipenem resistant.The bla_(ADC)and bla_(OXA-51-like) genes were detected in all isolates,in association with ISAba I sequence in 84% and 8% (imipenem resistant) of isolates,respectively.The bla_(OXA-23-like) and bla_(OXA-24-like)carbapenemase genes were delected in 67.02% and 20.21% of imipenem-resistant isolates,respectively.The bla_(OXA-23-like) gene is linked to ISAba1 or ISAba4 elements.The metallo-β-lactamase NDM-1 gene was found in 10(10.6% ) imipenem-resisianl strains from three hospitals,it is linked to ISAba125 clement in nine strains.Extended spectrum β-lactamases production was not detected.Imipenem and cefotaxime resistance phenolypes could not be transferred to Escherichia coli by conjugation.Outer membrane protein CarO gene was not delected in four imipenem-resisianl isolates.The aac(6')-1b.sul1,sul2,tetA and tetB genes were present in 5.31% .36.17% .77.65% .1.06% and 65.92% of strains,respectively.Class 1 integrons were detected in 23.4% strains.KRIC-PCR typing showed a genetic diversity among bla_(OXA-23-like) and bla_(OXA-24-like) positive strains,while clonality was observed among bla_(NDM-1)positives.Conclusions:This study highlighted the high prevalence of imipenem resistance in Acinetobacter baumannii in Algiers hospitals mediated mainly by bla_(OXA-23-like),bla_(OXA-24-like),and bla_(NDM-1) genes.展开更多
Acinetobacter baumannii is one of the most important human pathogens causing a variety of nosocomial infections. Carbapenem antibiotics have been primarily used to treat the A. baumannii infections. However, carbapene...Acinetobacter baumannii is one of the most important human pathogens causing a variety of nosocomial infections. Carbapenem antibiotics have been primarily used to treat the A. baumannii infections. However, carbapenem resistant A. baumannii producing carbapenemases causes serious treatment problems worldwide. Outbreaks of carbapenem resistant isolates have reported in some area of the United States, but their dissemination and genetic structure of the carbapenemase encoding genes are currently little known. To understand outbreaks, dissemination, and genetic structure of the carbapenemase encoding genes in Southern Texas, 32 clinical isolates collected from Austin and Houston, TX were characterized. Twenty-eight of 32 isolates were resistant to all tested β-lactam antibiotics including carbapenem (imipenem and meropenem). Three of them carried blaOXA-23 as a part of Tn2008 integrated into a known plasmid (pACICU2) and all others carried blaOXA-24 flanked by XerC/XerD-like recombinase binding sites that were adjoined by DNA sequences originated from multiple plasmids. Genotype analysis revealed that the 25 isolates carrying blaOXA-24 were all identical genotypes same as a representative isolate carrying blaOXA-24 from Chicago, IL but the 3 isolates carrying blaOXA-23 was a distinct genotype as compared with isolates carrying blaOXA-23 from Chicago, IL and Washington, D.C. Each of the blaOXA-23 and blaOXA-24 was transferred to carbapenem susceptible A. baumannii and E. coli with similar minimal inhibitory concentration (MIC) of carbapenem as that of their parental isolates but significantly lower levels of MIC in E. coli. Overall results suggest that a unique strain carrying blaOXA-23 and a similar strain carrying blaOXA-24 as seen in other geographic areas are currently disseminated in Southern Texas.展开更多
Background: Carbapenem-resistant Acinetobacter baumannii (CRAB) have been a challenging concern of health-care associated infections. The aim of the current study was to investigate the molecular epidemiology and clon...Background: Carbapenem-resistant Acinetobacter baumannii (CRAB) have been a challenging concern of health-care associated infections. The aim of the current study was to investigate the molecular epidemiology and clonal dissemination of CRAB isolates in a Chinese teaching hospital. Methods: Non-duplicate clinical A. baumannii isolates were collected from inpatients, and we measured the minimal inhibitory concentrations to determine antimicrobial susceptibility. Polymerase chain reaction (PCR) and sequencing were performed to detect carbapenem-resistance genes and occurrence of transposons among CRAB isolates. Moreover, the genetic diversity among isolates and clonal dissemination were determined by repetitive element PCR-mediated DNA fingerprinting (rep-PCR) and multilocus sequence typing (MLST). Results: A total of 67 CRAB isolates displayed resistance to most of the antibiotics tested in this study, except tigecycline. We detected bldOXA-23,bldOXA-51, bldOXAA-58, and bldVIM genes in 94.0%, 100.0%, 1.5%, and 80.6% of the CRAB isolates, respectively. Nevertheless, 74.6% of the CRAB isolates co-harbored the bldOXA-23 and bldVIM. Only one type of transposons was detected: Tn2008 (79.1%, 53/67). Although 12 distinctive types (A-L) were determined (primarily A type) STI95 was the most prevalent sequence type (ST). ST368, ST210, ST90, ST829, and ST136 were also detected, and all belonged to clonal complex 208 (CC208) and global complex 2 (GC2). Conclusion: The bldOXA-23 and bldVIM genes contributed to the resistance among CRAB isolates collected in our study. Notably, most of the CRAB strains co-harbored bldOXA-23 and vim genes, as well as Tn2008, which could contribute to clonal dissemination. The prevalence of such organisms may underlie hospital acquired infections.展开更多
Background:Acinetobacter baumannii(A.baumannii)is one of the pivotal pathogens responsible for nosocomial infections,especially in patients with low immune response,and infection with carbapenem-resistant A.baumannii ...Background:Acinetobacter baumannii(A.baumannii)is one of the pivotal pathogens responsible for nosocomial infections,especially in patients with low immune response,and infection with carbapenem-resistant A.baumannii has been increasing in recent years.Rapid and accurate detection of carbapenem-resistance genes in A.baumannii could be of immense help to clinical staff.Methods:In this study,a 15-μL reaction system for recombinase polymerase amplification(RPA)was developed and tested.We collected 30 clinical isolates of A.baumannii from the Burn Institute of Southwest Hospital of Third Military Medical University(Army Medical University)for 6 months and tested antibiotic susceptibility using the VITEK 2 system.A.baumannii was detected based on the blaOXA-51 gene by PCR,qPCR and 15μL-RPA,respectively.Sensitivity and specificity were evaluated.In addition,PCR and 15μL-RPA data for detecting the carbapenem-resistance gene blaOXA-23 were comparatively assessed.Results:The detection limit of the blaOXA-51 gene by 15μL RPA was 2.86 CFU/ml,with sensitivity comparable to PCR and qPCR.No positive amplification signals were detected in non-Acinetobacter isolates,indicating high specificity.However,only 18 minutes were needed for the 15μL RPA assay.Furthermore,an antibiotic susceptibility test showed that up to 90%of A.baumannii strains were resistant to meropenem and imipenem;15μL RPA data for detecting blaOXA-23 showed that only 10%(n=3)of A.baumannii isolates did not show positive amplification signals,and the other 90%of(n=27)isolates were positive,corroborating PCR results.Conclusion:We demonstrated that the new 15μL RPA assay for detecting blaOXA-23 in A.baumannii is faster and simpler than qPCR and PCR.It is a promising alternative molecular diagnostic tool for rapid and effective detection of A.baumannii and drug-resistance genes in the field and point-ofcare testing.展开更多
基金supported by grants from National Fund for the Research and National Agency for the Development of Research in Health(Algeria)
文摘Objective:To assess and characterize antibiotic resistance in Acinetobacter baumannii strains recovered from 5 health-care facilities in Algiers.Methods:Antibiotic susceptibility testing was performed by agar diffusion and agar dilution methods,resistance genes were identified by PCR and sequencing,and molecular typing of isolates was carried out by enterobacterial repetitive intergenic consensus-PCR(ERIC-PCR).Results:Among 125 tested isolates,117(93.6% ) were multidrug-resistant.of which 94(75.2% ) were imipenem resistant.The bla_(ADC)and bla_(OXA-51-like) genes were detected in all isolates,in association with ISAba I sequence in 84% and 8% (imipenem resistant) of isolates,respectively.The bla_(OXA-23-like) and bla_(OXA-24-like)carbapenemase genes were delected in 67.02% and 20.21% of imipenem-resistant isolates,respectively.The bla_(OXA-23-like) gene is linked to ISAba1 or ISAba4 elements.The metallo-β-lactamase NDM-1 gene was found in 10(10.6% ) imipenem-resisianl strains from three hospitals,it is linked to ISAba125 clement in nine strains.Extended spectrum β-lactamases production was not detected.Imipenem and cefotaxime resistance phenolypes could not be transferred to Escherichia coli by conjugation.Outer membrane protein CarO gene was not delected in four imipenem-resisianl isolates.The aac(6')-1b.sul1,sul2,tetA and tetB genes were present in 5.31% .36.17% .77.65% .1.06% and 65.92% of strains,respectively.Class 1 integrons were detected in 23.4% strains.KRIC-PCR typing showed a genetic diversity among bla_(OXA-23-like) and bla_(OXA-24-like) positive strains,while clonality was observed among bla_(NDM-1)positives.Conclusions:This study highlighted the high prevalence of imipenem resistance in Acinetobacter baumannii in Algiers hospitals mediated mainly by bla_(OXA-23-like),bla_(OXA-24-like),and bla_(NDM-1) genes.
文摘Acinetobacter baumannii is one of the most important human pathogens causing a variety of nosocomial infections. Carbapenem antibiotics have been primarily used to treat the A. baumannii infections. However, carbapenem resistant A. baumannii producing carbapenemases causes serious treatment problems worldwide. Outbreaks of carbapenem resistant isolates have reported in some area of the United States, but their dissemination and genetic structure of the carbapenemase encoding genes are currently little known. To understand outbreaks, dissemination, and genetic structure of the carbapenemase encoding genes in Southern Texas, 32 clinical isolates collected from Austin and Houston, TX were characterized. Twenty-eight of 32 isolates were resistant to all tested β-lactam antibiotics including carbapenem (imipenem and meropenem). Three of them carried blaOXA-23 as a part of Tn2008 integrated into a known plasmid (pACICU2) and all others carried blaOXA-24 flanked by XerC/XerD-like recombinase binding sites that were adjoined by DNA sequences originated from multiple plasmids. Genotype analysis revealed that the 25 isolates carrying blaOXA-24 were all identical genotypes same as a representative isolate carrying blaOXA-24 from Chicago, IL but the 3 isolates carrying blaOXA-23 was a distinct genotype as compared with isolates carrying blaOXA-23 from Chicago, IL and Washington, D.C. Each of the blaOXA-23 and blaOXA-24 was transferred to carbapenem susceptible A. baumannii and E. coli with similar minimal inhibitory concentration (MIC) of carbapenem as that of their parental isolates but significantly lower levels of MIC in E. coli. Overall results suggest that a unique strain carrying blaOXA-23 and a similar strain carrying blaOXA-24 as seen in other geographic areas are currently disseminated in Southern Texas.
基金grants from the Hunan Provincial Natural Science Foundation (No. 2017JJ3478)the National Natural Science Foundation of China (No. 81702068).
文摘Background: Carbapenem-resistant Acinetobacter baumannii (CRAB) have been a challenging concern of health-care associated infections. The aim of the current study was to investigate the molecular epidemiology and clonal dissemination of CRAB isolates in a Chinese teaching hospital. Methods: Non-duplicate clinical A. baumannii isolates were collected from inpatients, and we measured the minimal inhibitory concentrations to determine antimicrobial susceptibility. Polymerase chain reaction (PCR) and sequencing were performed to detect carbapenem-resistance genes and occurrence of transposons among CRAB isolates. Moreover, the genetic diversity among isolates and clonal dissemination were determined by repetitive element PCR-mediated DNA fingerprinting (rep-PCR) and multilocus sequence typing (MLST). Results: A total of 67 CRAB isolates displayed resistance to most of the antibiotics tested in this study, except tigecycline. We detected bldOXA-23,bldOXA-51, bldOXAA-58, and bldVIM genes in 94.0%, 100.0%, 1.5%, and 80.6% of the CRAB isolates, respectively. Nevertheless, 74.6% of the CRAB isolates co-harbored the bldOXA-23 and bldVIM. Only one type of transposons was detected: Tn2008 (79.1%, 53/67). Although 12 distinctive types (A-L) were determined (primarily A type) STI95 was the most prevalent sequence type (ST). ST368, ST210, ST90, ST829, and ST136 were also detected, and all belonged to clonal complex 208 (CC208) and global complex 2 (GC2). Conclusion: The bldOXA-23 and bldVIM genes contributed to the resistance among CRAB isolates collected in our study. Notably, most of the CRAB strains co-harbored bldOXA-23 and vim genes, as well as Tn2008, which could contribute to clonal dissemination. The prevalence of such organisms may underlie hospital acquired infections.
文摘Background:Acinetobacter baumannii(A.baumannii)is one of the pivotal pathogens responsible for nosocomial infections,especially in patients with low immune response,and infection with carbapenem-resistant A.baumannii has been increasing in recent years.Rapid and accurate detection of carbapenem-resistance genes in A.baumannii could be of immense help to clinical staff.Methods:In this study,a 15-μL reaction system for recombinase polymerase amplification(RPA)was developed and tested.We collected 30 clinical isolates of A.baumannii from the Burn Institute of Southwest Hospital of Third Military Medical University(Army Medical University)for 6 months and tested antibiotic susceptibility using the VITEK 2 system.A.baumannii was detected based on the blaOXA-51 gene by PCR,qPCR and 15μL-RPA,respectively.Sensitivity and specificity were evaluated.In addition,PCR and 15μL-RPA data for detecting the carbapenem-resistance gene blaOXA-23 were comparatively assessed.Results:The detection limit of the blaOXA-51 gene by 15μL RPA was 2.86 CFU/ml,with sensitivity comparable to PCR and qPCR.No positive amplification signals were detected in non-Acinetobacter isolates,indicating high specificity.However,only 18 minutes were needed for the 15μL RPA assay.Furthermore,an antibiotic susceptibility test showed that up to 90%of A.baumannii strains were resistant to meropenem and imipenem;15μL RPA data for detecting blaOXA-23 showed that only 10%(n=3)of A.baumannii isolates did not show positive amplification signals,and the other 90%of(n=27)isolates were positive,corroborating PCR results.Conclusion:We demonstrated that the new 15μL RPA assay for detecting blaOXA-23 in A.baumannii is faster and simpler than qPCR and PCR.It is a promising alternative molecular diagnostic tool for rapid and effective detection of A.baumannii and drug-resistance genes in the field and point-ofcare testing.
