文章基本信息

标题：Increasing prevalence of ciprofloxacin-resistant food-borne Salmonella strains harboring multiple PMQR elements but not target gene mutations
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作者：Dachuan Lin ; Kaichao Chen ; Edward Wai-Chi Chan 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2015
卷号：5
DOI：10.1038/srep14754
出版社：Springer Nature
摘要：Fluoroquinolone resistance in Salmonella has become increasingly prevalent in recent years. To probe the molecular basis of this phenomenon, the genetic and phenotypic features of fluoroquinolone resistant Salmonella strains isolated from food samples were characterized. Among the 82 Salmonella strains tested, resistance rate of the three front line antibiotics of ceftriaxone, ciprofloxacin and azithromycin was 10%, 39% and 25% respectively, which is significantly higher than that reported in other countries. Ciprofloxacin resistant strains typically exhibited cross-resistance to multiple antibiotics including ceftriaxone, primarily due to the presence of multiple PMQR genes and the bla _CTX-M-65, bla _CTX-M-55 bla _CMY-2 and bla _CMY-72 elements. The prevalence rate of the oqxAB and aac(6’)-Ib-cr genes were 91% and 75% respectively, followed by qnrS (66%), qnrB (16%) and qnrD (3%). The most common PMQR combination observable was aac(6’)-Ib-cr - oqxAB - qnrS 2, which accounted for 50% of the ciprofloxacin resistant strains. Interestingly, such isolates contained either no target mutations or only a single gyrA mutation. Conjugation and hybridization experiments suggested that most PMQR genes were located either in the chromosome or a non-transferrable plasmid. To summarize, findings in this work suggested that PMQRs greatly facilitate development of fluoroquinolone resistance in Salmonella by abolishing the requirement of target gene mutations.