<strong>Background:</strong> Enterobacteriaceae causes many types of infections which are often treated with quinolones and fluoroquinolone (Q/FQ). The resistance mechanisms to Q/FQ are usually associated ...<strong>Background:</strong> Enterobacteriaceae causes many types of infections which are often treated with quinolones and fluoroquinolone (Q/FQ). The resistance mechanisms to Q/FQ are usually associated with mutations in the quinolone resistance determining region which alter the conformation of target amino acid residues within the protein and in the <em>qnr</em> genes. This study aimed at determining the antimicrobial resistant profile of a sample of Enterobacteriaceae from Cameroon and the genetic diversity in quinolone-resistant isolates in view of implementing a better management, treatment, control and prevention of the transmission of these resistant strains. <strong>Methods:</strong> Identification and antimicrobial susceptibility testing was done using VITEK 2. The detection of plamid-mediated quinolone resistance (PMQR) genes was carried out using the conventional PCR method. Sequencing was done using the Applied Biosystem 3500 genetic analyser. DNA fingerprint was obtained using Pulsed-Field Gel electrophoresis. <strong>Results:</strong> Among 440 Enterobacteriaceae, the most prevalent genera were: <em>Escherichia</em> 178/440 (39.5%);<em>Klebsiella</em> 148/440 (33.6%);<em>Enterobacter </em>35/440 (8%);<em>Pantoea</em> 28/440 (6.4%);<em>Proteus</em> 14/440 (3.2%) <em>Salmonella </em>13/440 (3%). Ampicillin resistance showed the highest prevalence with 371/440 (81%) and Imipenem the lowest resistance 9/440 (2.1%). The ciprofloxacin resistance rate was 161/440 (36.6%). The detected plasmid mediated quinolone resistance (PMQR) genes were: <em>qnrA</em>, 2/161 (1.2%);<em>qnrB</em>, 31/161 (19.3%);<em>qnrS</em>, 13/161 (8.1%): <em>Aac</em> (6')<em>Ib-cr</em>, 84/161 (52.2%) and <em>qepA</em>, 3/161 (1.9%). There were several mutations in the <em>parC</em> gene of <em>Klebsiella</em> leading to S80D and S80N substitutions. Two pairs of <em>Klebsiella</em> <em>peumoniae</em> strains were phenotypically and genotypically identical with 100% similarity in the dendrogramme. <strong>Conclusion:</strong> This study showed that quinolone resistance was high. The PMQR genes contributing to this resistance were diverse. This high PMQR indicates that there has been an unknown circulation of these genes in our community. To avoid the rapid dissemination of these PMQR genes continuous surveillance of antimicrobial resistance should be carried out not only in humans but also in animals to monitor the evolution of these genes.展开更多
Salmonella Corvallis ST1541 has recently emerged as a globally disseminated pathogenic strain that often causes severe food-borne infections.Unlike most pandemic serotypes of Salmonella,the ST1541 strains harbored Col...Salmonella Corvallis ST1541 has recently emerged as a globally disseminated pathogenic strain that often causes severe food-borne infections.Unlike most pandemic serotypes of Salmonella,the ST1541 strains harbored ColRNA1 plasmids that contain qnr-like determinants known to be responsible for the increasing incidence of ciprofloxacin-resistant food-borne Salmonella infections.In this study,we conducted a genomic analysis of a global collection of 388 S.Corvallis ST1541 strains collected within a twenty-year period.We investigated the genetic characteristics of plasmid-mediated quinolone resistance(PMQR)plasmids harbored by these S.Corvallis strains,established a mini-mum spanning tree(MST)to determine the temporal and spatial distribution of the top 10 MST clusters,inferred a time-phylogenies for the major sub-lineages and traced the routes of international dissemination of this serotype strains.Bayesian algorithm predicted that UK might be the origin of S.Corvallis strains currently prevalent in various countries.This idea is supported by the observation of the emergence of intercontinental-disseminated clonal strains and extensive transmission of the extensive-drug resistance(XDR)-encoding plasmid pSA663.This study there-fore provides valuable insight into the evolution of globally transmitted S.Corvallis strains and suggests a need to strengthen cooperation between different countries to control the dissemination of these drug-resistant bacteria.展开更多
文摘<strong>Background:</strong> Enterobacteriaceae causes many types of infections which are often treated with quinolones and fluoroquinolone (Q/FQ). The resistance mechanisms to Q/FQ are usually associated with mutations in the quinolone resistance determining region which alter the conformation of target amino acid residues within the protein and in the <em>qnr</em> genes. This study aimed at determining the antimicrobial resistant profile of a sample of Enterobacteriaceae from Cameroon and the genetic diversity in quinolone-resistant isolates in view of implementing a better management, treatment, control and prevention of the transmission of these resistant strains. <strong>Methods:</strong> Identification and antimicrobial susceptibility testing was done using VITEK 2. The detection of plamid-mediated quinolone resistance (PMQR) genes was carried out using the conventional PCR method. Sequencing was done using the Applied Biosystem 3500 genetic analyser. DNA fingerprint was obtained using Pulsed-Field Gel electrophoresis. <strong>Results:</strong> Among 440 Enterobacteriaceae, the most prevalent genera were: <em>Escherichia</em> 178/440 (39.5%);<em>Klebsiella</em> 148/440 (33.6%);<em>Enterobacter </em>35/440 (8%);<em>Pantoea</em> 28/440 (6.4%);<em>Proteus</em> 14/440 (3.2%) <em>Salmonella </em>13/440 (3%). Ampicillin resistance showed the highest prevalence with 371/440 (81%) and Imipenem the lowest resistance 9/440 (2.1%). The ciprofloxacin resistance rate was 161/440 (36.6%). The detected plasmid mediated quinolone resistance (PMQR) genes were: <em>qnrA</em>, 2/161 (1.2%);<em>qnrB</em>, 31/161 (19.3%);<em>qnrS</em>, 13/161 (8.1%): <em>Aac</em> (6')<em>Ib-cr</em>, 84/161 (52.2%) and <em>qepA</em>, 3/161 (1.9%). There were several mutations in the <em>parC</em> gene of <em>Klebsiella</em> leading to S80D and S80N substitutions. Two pairs of <em>Klebsiella</em> <em>peumoniae</em> strains were phenotypically and genotypically identical with 100% similarity in the dendrogramme. <strong>Conclusion:</strong> This study showed that quinolone resistance was high. The PMQR genes contributing to this resistance were diverse. This high PMQR indicates that there has been an unknown circulation of these genes in our community. To avoid the rapid dissemination of these PMQR genes continuous surveillance of antimicrobial resistance should be carried out not only in humans but also in animals to monitor the evolution of these genes.
基金supported by the Key Research and Development Program of Guangdong Province(Grant number,2022B1111040002)the Collaborative Research Fund from Research Grant Council of the Government of Hong Kong SAR(Grant numbers,C7147-20G,C7003-20G).
文摘Salmonella Corvallis ST1541 has recently emerged as a globally disseminated pathogenic strain that often causes severe food-borne infections.Unlike most pandemic serotypes of Salmonella,the ST1541 strains harbored ColRNA1 plasmids that contain qnr-like determinants known to be responsible for the increasing incidence of ciprofloxacin-resistant food-borne Salmonella infections.In this study,we conducted a genomic analysis of a global collection of 388 S.Corvallis ST1541 strains collected within a twenty-year period.We investigated the genetic characteristics of plasmid-mediated quinolone resistance(PMQR)plasmids harbored by these S.Corvallis strains,established a mini-mum spanning tree(MST)to determine the temporal and spatial distribution of the top 10 MST clusters,inferred a time-phylogenies for the major sub-lineages and traced the routes of international dissemination of this serotype strains.Bayesian algorithm predicted that UK might be the origin of S.Corvallis strains currently prevalent in various countries.This idea is supported by the observation of the emergence of intercontinental-disseminated clonal strains and extensive transmission of the extensive-drug resistance(XDR)-encoding plasmid pSA663.This study there-fore provides valuable insight into the evolution of globally transmitted S.Corvallis strains and suggests a need to strengthen cooperation between different countries to control the dissemination of these drug-resistant bacteria.
