亚抑菌浓度头孢西丁对耐药质粒接合转移的影响

Influence of subinhibitory concentration of cefoxitin on resistant plasmid conjugation

目的探讨亚抑菌浓度头孢西丁对耐药质粒接合转移的影响,研究病原菌耐药性播散的产生机制。方法采用聚合酶链反应(PCR)分析临床分离的63株产超广谱β-内酰胺酶(ESBLs)肺炎克雷伯菌株SHV型β-内酰胺酶编码基因。质粒接合转移试验采用肉汤接合法。研究不同亚抑菌浓度头孢西丁(0、1、0.5、0.25、0.125μg/mL)和不同作用时间(2、4、6、8、10、12 h)下临床产ESBLs肺炎克雷伯菌株供体菌与受体菌大肠埃希菌C600接合转移频率的变化。结果63株临床分离的产ESBLs肺炎克雷伯菌株有41株扩增出SHV型基因,阳性率为65.1%。随着亚抑菌浓度头孢西丁作用时间的增加,接合转移频率随之增加。在相同作用时间下,头孢西丁浓度为0.125μg/mL作用下的接合转移频率高于其他亚抑菌浓度的作用。结论不同亚抑菌浓度头孢西丁能影响耐药质粒的转移。临床使用抗生素时,应考虑到给药间歇期间亚抑菌浓度的变化,及时调整治疗方案,防止细菌耐药性的播散。

Objective To investigate the influence of sub-minimum inhibitory concentration（ sub-MIC ）of cefoxitin on resistant plasmid conjugation and study the mechanism of resistance spread in pathogen. Methods The genotypes of SHV of 63 clinical isolates of extended-spectrum β-1actamase （ ESBLs ） -producing Klebsiella pneumoniae （ K. pneumoniae） were analysed by polymerase chain reaction （PCR）. Plasmid conjugation was performed by broth mating method. To analyse the changes of transfer rate of the conjugation between the donor （ clinical isolate of ESBLs-producing K. pneumoniae） and recipient （Escherichia coli C600 ）at the presence of different subinhibitory concentrations of cefoxitin （0, 1,0.5,0.25,0. 125 μg/mL）and different reaction time（2,4,6,8,10,12 h） in vitro. Results The positive rate of 63 clinical isolates of K. pneumoniae strains harbored SHV type was 65.1% （41/63）. The transfer rate increased with the prolonging time of the presence of sub-MIC. At the same time,in the presence of 0. 125 μg/mL cefoxitin, the transfer rate was the highest. Conclusions The presence of different subinhibitory concentrations of cefoxitin may effect the transfer of resistant plasmid. When clinicians use antibiotic, they should consider these changes of subinhibitory concentrations of antibiotic in the treatment,choose a better therapy in time and decrease the spread of resistance bacteria.