嗜麦芽寡养单胞菌分子流行病学的研究

Molecular Epidemiology of Stenotrophomonas maltophilia

目的探讨嗜麦芽寡养单胞菌分子流行病学特点,为预防与控制医院感染提供理论依据。方法对92株嗜麦芽寡养单胞菌进行脉冲场凝胶电泳(PFGE)同源性分析,细菌包埋在低熔点琼脂糖中,经染色体DNA的原位纯化后,用低频限制性内切酶XbaⅠ进行染色体DNA的原位消化;使用PFGE对限制性酶切片段进行分离,通过对染色体DNA限制性内切酶谱比较,确定菌株亲缘关系。结果嗜麦芽寡养单胞菌为多克隆构成模式,92株菌共有63个克隆;有10个克隆出现了克隆传播,涉及39株菌;克隆A涉及10个菌株,分离间期最长达24个月,克隆A中来自同一医院的9株菌中有5株来自外科ICU,3株来自呼吸病房;克隆E有7个菌株,经过4次传播后,环丙沙星的MIC值由1 mg/L升高至8 mg/L。结论同一医疗单元环境的污染是克隆传播的主要原因;不同医疗单元医源性传播是克隆传播的主要途径;克隆传播是细菌产生耐药的原因之一。

OBJECTIVE To investigate the molecular epidemiological characteristics of Stenotrophomonas maltophilia（SMA）,and to supply theoretical foundation for preventing or controlling nosocomial infection.METHODS A total of 92 SMA strains were analyzed by pulsed-field gel electrophoresis（PFGE）.Cells were imbedded in low melting point agarose.DNA was digested with low-frequency-cleavage restriction endonucleases in situ after purified.The intact DNA was electrophoresed in pulsed field.Relatedness of isolates was demonstrated by comparison of their fingerprints.RESULTS There were 63 clones in the 92 clinical isolates.A total of 39 isolates were detected out by clone-transmission.Clone A inclnded 10 isolates,9 of which were isolated from the same hospital,5 from surgical ICU ward and 3 from respiratory ward,and the longest interval was 24 months.The MIC of ciprofloxacin increased from 1 mg/L to 8 mg/L in clone E after four times transmission.CONCLUSIONS Environmental contamination contributes to SMA epidemic dissemination in the same medical unit.Medical transmission is the main route of dissemination among different units.Clone transmission is one of the reasons of drug-resistance.