Food Safety and Technology Research Centre, Hong Kong Polytechnic University - Shenzhen Research Institute Shenzhen, China ; State Key Laboratory of Chirosciences, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University Kowloon, China.
Department of Microbiology, The Prince of Wales Hospital - The Chinese University of Hong Kong Shatin, China.
Front Microbiol. 2014 Oct 2;5:521. doi: 10.3389/fmicb.2014.00521. eCollection 2014.
Emergence of multidrug-resistant Salmonella typhimurium strains, especially the ACSSuT and nalidixic acid R types, has significantly compromised the effectiveness of current strategies to control Salmonella infections, resulting in increased morbidity and mortality. Clinical S. typhimurium isolates recovered in Hong Kong during the period of 2005-2011 were increasingly resistant to ciprofloxacin (CIP) and antibiotics of the ACSSuT group. Our data revealed that oqxAB and aac(6')Ib-cr were encoded on plasmids of various sizes and the presence of these two elements together with a single gyrA mutation in S. typhimurium were sufficient to mediate resistance to CIP. Acquisition of the oqxAB and aac(6')Ib-cr encoding plasmids by S. typhimurium caused a fourfold increase in CIP minimal inhibitory concentration. Furthermore, the presence of oqxAB and aac(6')Ib-cr in Salmonella dramatically increased the mutation prevention concentration of CIP which may due to mutational changes in the drug target genes. In conclusion, possession of oqxAB and aac(6')Ib-cr encoding plasmid facilitate the selection of CIP resistant S. typhimurium, thereby causing a remarkable increase of CIP resistance among clinical Salmonella strains in Hong Kong.
多重耐药鼠伤寒沙门氏菌菌株的出现，尤其是 ACSSuT 和萘啶酸 R 型，大大降低了当前控制沙门氏菌感染策略的有效性，导致发病率和死亡率上升。2005-2011 年期间，在香港分离的临床鼠伤寒沙门氏菌分离株对环丙沙星（CIP）和 ACSSuT 组抗生素的耐药性逐渐增加。我们的数据显示，oqxAB 和 aac(6')Ib-cr 编码在大小不同的质粒上，oqxAB 和 aac(6')Ib-cr 这两个元件与 S. typhimurium 中的单个 gyraA 突变一起存在足以介导对 CIP 的耐药性。oqxAB 和 aac(6')Ib-cr 编码质粒的获得使鼠伤寒沙门氏菌对 CIP 的最小抑菌浓度增加了四倍。此外，oqxAB 和 aac(6')Ib-cr 在沙门氏菌中的存在大大增加了 CIP 的突变预防浓度，这可能是由于药物靶基因的突变。总之，oqxAB 和 aac(6')Ib-cr 编码质粒的存在促进了 CIP 耐药鼠伤寒沙门氏菌的选择，从而导致香港临床沙门氏菌菌株对 CIP 的耐药性显著增加。
