biostudies-literatureUnknown12Liu G<b>Background:</b> This study analyzed the antimicrobial resistance phenotypes and mechanisms of quinolone, cephalosporins, and colistin resistance in nontyphoidal <i>Salmonella</i> from patients with diarrhea in Jiangsu, China. <b>Methods:</b> A total of 741 nontyphoidal <i>Salmonella</i> isolates were collected from hospitals in major cities of Jiangsu Province, China between 2016 and 2017. Their susceptibility to commonly used antibiotics was evaluated by broth micro-dilution and sequencing analysis of resistance genes screened by a PCR method. For <i>mcr-1</i> positive isolates, genetic relationship study was carried out by pulsed-field gel electrophoresis and multiloci sequence typing analysis. The transferability of these plasmids was measured with conjugation experiments and the genetic locations of <i>mcr-1</i> were analyzed by pulsed-field gel electrophoresis profiles of S1-digested genomic DNA and subsequent Southern blot hybridization. <b>Results:</b> Among 741 nontyphoidal <i>Salmonella</i> isolates, the most common serotypes identified were <i>S.</i> Typhimurium (<i>n</i>=257, 34.7%) and <i>S.</i> Enteritidis (<i>n</i>=127, 17.1%), and the isolates showed 21.7, 20.6, and 5.0% resistance to cephalosporins, ciprofloxacin, and colistin, respectively. Among the 335 nalidixic acid-resistant <i>Salmonella</i>, 213 (63.6%) and 45 (13.4%) had at least one mutation in <i>gyrA</i> and <i>parC</i>. Among the plasmid-borne resistance, <i>qnrS1</i> (85; 41.9%) and <i>aac(6')-Ib-cr4</i> (75; 36.9%) were the most common quinolone resistance (PMQR) genes, while <i>bla</i> _CTX-M-14 (<i>n</i>=35) and <i>bla</i> _CTX-M-55 (<i>n</i>=46) were found to be dominant extended-spectrum beta-lactamase (ESBL) genes in nontyphoidal <i>Salmonella</i>. In addition, eight <i>mcr-1</i>-harboring strains were detected since 2016 and they were predominate in children under the age of 7years. Conjugation assays showed the donor <i>Salmonella</i> strain has functional and transferable colistin resistance and Southern blot hybridization revealed that <i>mcr-1</i> was located in a high molecular weight plasmid. <b>Conclusion:</b> In nontyphoidal <i>Salmonella</i>, there is a rapidly increasing trend of colistin resistance and this is the first report of patients harboring <i>mcr-1</i>-positive <i>Salmonella</i> with a new ST type ST155 and new serotype <i>S.</i> Sinstorf. These findings demonstrate the necessity for cautious use and the continuous monitoring of colistin in clinical applications.Frontiers in microbiology723697https://www.ebi.ac.uk/biostudies/studies/S-EPMC8483771biostudies-literatureEmergence of <i>mcr-1</i>-Harboring <i>Salmonella enterica</i> Serovar Sinstorf Type ST155 Isolated From Patients With Diarrhea in Jiangsu, China.PMC8483771Qian HLv JGu BTian BBao CYan HLiu GfalseEmergence of <i>mcr-1</i>-Harboring <i>Salmonella enterica</i> Serovar Sinstorf Type ST155 Isolated From Patients With Diarrhea in Jiangsu, China.<b>Background:</b> This study analyzed the antimicrobial resistance phenotypes and mechanisms of quinolone, cephalosporins, and colistin resistance in nontyphoidal <i>Salmonella</i> from patients with diarrhea in Jiangsu, China. <b>Methods:</b> A total of 741 nontyphoidal <i>Salmonella</i> isolates were collected from hospitals in major cities of Jiangsu Province, China between 2016 and 2017. Their susceptibility to commonly used antibiotics was evaluated by broth micro-dilution and sequencing analysis of resistance genes screened by a PCR method. For <i>mcr-1</i> positive isolates, genetic relationship study was carried out by pulsed-field gel electrophoresis and multiloci sequence typing analysis. The transferability of these plasmids was measured with conjugation experiments and the genetic locations of <i>mcr-1</i> were analyzed by pulsed-field gel electrophoresis profiles of S1-digested genomic DNA and subsequent Southern blot hybridization. <b>Results:</b> Among 741 nontyphoidal <i>Salmonella</i> isolates, the most common serotypes identified were <i>S.</i> Typhimurium (<i>n</i>=257, 34.7%) and <i>S.</i> Enteritidis (<i>n</i>=127, 17.1%), and the isolates showed 21.7, 20.6, and 5.0% resistance to cephalosporins, ciprofloxacin, and colistin, respectively. Among the 335 nalidixic acid-resistant <i>Salmonella</i>, 213 (63.6%) and 45 (13.4%) had at least one mutation in <i>gyrA</i> and <i>parC</i>. Among the plasmid-borne resistance, <i>qnrS1</i> (85; 41.9%) and <i>aac(6')-Ib-cr4</i> (75; 36.9%) were the most common quinolone resistance (PMQR) genes, while <i>bla</i> _CTX-M-14 (<i>n</i>=35) and <i>bla</i> _CTX-M-55 (<i>n</i>=46) were found to be dominant extended-spectrum beta-lactamase (ESBL) genes in nontyphoidal <i>Salmonella</i>. In addition, eight <i>mcr-1</i>-harboring strains were detected since 2016 and they were predominate in children under the age of 7years. Conjugation assays showed the donor <i>Salmonella</i> strain has functional and transferable colistin resistance and Southern blot hybridization revealed that <i>mcr-1</i> was located in a high molecular weight plasmid. <b>Conclusion:</b> In nontyphoidal <i>Salmonella</i>, there is a rapidly increasing trend of colistin resistance and this is the first report of patients harboring <i>mcr-1</i>-positive <i>Salmonella</i> with a new ST type ST155 and new serotype <i>S.</i> Sinstorf. These findings demonstrate the necessity for cautious use and the continuous monitoring of colistin in clinical applications.2021-01-01T00:00:00Z20212024-11-07T09:26:48.052Z2022-02-11T11:45:46.47ZS-EPMC84837713460324910.3389/fmicb.2021.723697