Correa J E, De Paulis A, Predari S, Sordelli D O, Jeric P E
Departamento de Microbiología, Inmunología y Parasitología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
J Antimicrob Chemother. 2008 Nov;62(5):956-60. doi: 10.1093/jac/dkn327. Epub 2008 Aug 15.
To investigate phenotypically and genotypically the presence of MDR efflux pumps in 21 clinical isolates of Staphylococcus haemolyticus collected over a period of 10 years.
MICs of different antibiotics and biocides were determined by the broth dilution method in the presence/absence of carbonyl cyanide-m-chlorophenylhydrazone (CCCP), an efflux pump inhibitor. PCR followed by sequencing was performed to detect the qac genes that encode for antiseptic resistance. Clonal relationships were determined by PFGE SmaI patterns using a standard protocol.
All the isolates were resistant to gentamicin, 15 to erythromycin, 18 to ciprofloxacin, 7 to chloramphenicol and 1 to tetracycline. They showed higher susceptibility to antibiotics when they were exposed to CCCP. The MICs of ethidium bromide, SDS and benzalkonium chloride were also decreased, whereas the MIC of triclosan was decreased in only four isolates in the presence CCCP. Of the 21 isolates, qacA/B was detected in 5 isolates, smr in all of the isolates, qacG in 11 isolates, qacH in 10 isolates and qacJ in 4 isolates. PFGE analysis of the 21 isolates clustered them into 14 clones at 90% similarity corresponding to differences of between 7 and 16 bands among the clones.
The efflux mechanism seems to be an important mechanism to confer resistance to antibiotics and biocides through MDR pumps. It was observed that several qac genes coexist in some of the isolates and seem to act simultaneously in the removal of different compounds out of the bacterial cell. The qac genes are horizontally spread among different clones.
对10年间收集的21株溶血葡萄球菌临床分离株进行多药耐药外排泵的表型和基因型研究。
采用肉汤稀释法，在有/无外排泵抑制剂羰基氰化物间氯苯腙（CCCP）存在的情况下，测定不同抗生素和杀菌剂的最低抑菌浓度（MIC）。进行聚合酶链反应（PCR）及测序以检测编码抗防腐剂耐药性的qac基因。使用标准方案通过脉冲场凝胶电泳（PFGE）SmaI图谱确定克隆关系。
所有分离株均对庆大霉素耐药，15株对红霉素耐药，18株对环丙沙星耐药，7株对氯霉素耐药，1株对四环素耐药。当暴露于CCCP时，它们对抗生素的敏感性更高。溴化乙锭、十二烷基硫酸钠和苯扎氯铵的MIC也降低，而在CCCP存在的情况下，仅4株分离株的三氯生MIC降低。在21株分离株中，5株检测到qacA/B，所有分离株均检测到smr，11株检测到qacG，10株检测到qacH，4株检测到qacJ。对21株分离株的PFGE分析将它们聚类为14个克隆，相似度为90%，对应克隆间7至16条带的差异。
外排机制似乎是通过多药耐药泵赋予对抗生素和杀菌剂耐药性的重要机制。观察到一些分离株中存在几种qac基因，它们似乎同时作用于将不同化合物排出细菌细胞。qac基因在不同克隆间水平传播。
