解脲脲原体对红霉素耐药机制的初步研究

目的 探讨解脲脲原体对红霉素的耐药机制。方法 对73株从泌尿生殖道分离的解脲脲原体进行体外药物敏感试验筛选耐药菌株，并设立临床敏感菌株组以及标准菌株对照组，用PCR测序法检测23SrRNA的V区热点突变以及特异性引物PCR检测甲基化酶（ermA、ermB、ermC）、主动外排泵（mefA/E、msrA/B、mreA）等可转移耐药基因。结果 73株临床菌株中，耐药菌株35株（47.95%），耐药菌株MIC范围为8 ~ 32 mg/L。在耐药菌株组发现ermB耐药基因（19株，占54.29%）和msrA/B耐药基因（9株，占25.71%）的阳性扩增，其中有2株（占5.71%）同时存在ermB基因和msrA/B基因阳性扩增，ermB基因和msrA/B基因的阳性扩增比率差异有统计学意义（P < 0.05）。临床敏感菌株组及标准菌株组均未发现23SrRNA的V区点突变及可转移耐药基因的阳性扩增。结论 ermB甲基化酶基因和msrA/B外派泵基因可能是导致解脲脲原体对红霉素耐药原因之一。

A preliminary study on the resistance mechanism of Ureaplasma urealyticum to erythromycin

Objective To study the resistance mechanism of Ureaplasma urealyticum (Uu) to erythromycin.Methods The susceptibility of 73 clinical isolates of Uu to erythromycin was evaluated by using broth dilution techniques. PCR and DNA sequencing were carried out to screen hot spot mutations at the variable region of 23S ribosomal RNA in erythromycin-resistant strains of Uu. Moreover, erythromycin resistance methylase genes (ermA, ermB, ermC) and efflux pump genes (mefA/E, msrA/B, mreA) were screened by using PCR with specific primers. Results There were 35 (47.95%) resistant Uu strains out of the 73 isolates, and the minimal inhibitory concentration varied from 8 to 32 mg/L among these resistant strains. The ermB gene was detected in 19 (54.29%) resistant strains, and msrA/B gene in 9 (25.71%) resistant strains. Two resistant strains harbored both ermB gene and msrA/B gene. No mutation at 23S ribosomal RNA or amplification of resistance-associated genes was noted in sensitive or reference strains of Uu. Conclusion The ermB and msrA/B genes may be responsible for the erythromycin resistance of Uu.