上海某医院临床分离嗜麦芽窄食单胞菌分子流行病学分析

摘要

目的 研究上海交通大学医学院附属仁济医院成人患者分离嗜麦芽窄食单胞菌的分子流行病学特征,为嗜麦芽窄食单胞菌的感控提供数据支持.方法 收集2014年1-9月该医院成人患者分离的非重复嗜麦芽窄食单胞菌,采用多位点序列分型(MLST)和脉冲场凝胶电泳(PFGE)方法分析其克隆特点;用纸片扩散法测定3种抗菌药物(左氧氟沙星,甲氧苄啶-磺胺甲嗯唑,米诺环素)的敏感性;PCR检测4种主要毒力基因(Stmprl,Stmpr2,smf-1,Smlt3773locus);采用半定量生物膜形成试验分析其生物膜形成能力;同时收集和分析患者的临床信息.结果 共收集78株嗜麦芽窄食单胞菌,26株来自外科监护室,其余较为分散.检出患者以男性为主占67.9％(53/78),在分离出嗜麦芽窄食单胞菌之前都有抗菌药物应用史,62.8％患者使用3种以上抗菌药物.MLST分析检测出38种新的ST型,命名为STnew1-STnew38,嗜麦芽窄食单胞菌的型别较为分散,较多的ST23型只有6株,克隆流行传播趋势不明显.PFGE显示78株菌株分成58个簇群,无明显聚集的簇群.78株菌株对左氧氟沙星、甲氧苄啶-磺胺甲(嗯)唑的耐药率分别为2.6％(2/78)、10.3％(8/78),所有菌株对米诺环素均敏感.Stmpr1、Stmpr2、smf-1和Smlt3773locus毒力基因阳性率分别为79.5％(62/78)、93.6％(73/78)、94.9％(74/78)和48.7％(38/78).生物膜形成试验结果显示:生物膜形成能力平均值为D492=0.51±0.44,不同性别的患者中无明显差异.结论 嗜麦芽窄食单胞菌检出患者以男性居多,感染患者大多有抗菌药物应用史,毒力基因携带率较高.未发现同一科室明显的克隆传播.%Objective We evaluated the molecular epidemiology ofStenotrophomonas maltophilia strains in adult patients in Renji Hospital to Shanghai Jiao Tong University School of Medicine for better control ofS.maltophilia infections.Methods Nonduplicate clinical isolates of S.maltophilia were collected from Renji Hospital from January 2014 to September 2014.We examined the clonality among the S.maltophilia isolates by multilocus sequence typing (MLST) and pulsed field gel electrophoresis (PFGE).Antimicrobial resistance pattern was investigated by Kirby-Bauer method and prevalence of toxin genes (Stmpr1,Stmpr2,stmr-1,Smlt3773locus) by PCR.We also studied the biofilm formation of S.maltophilia by semiquantitative biofilm formation test.Results A total of 78 nonduplicate S.maltophilia isolates were analyzed,of which 26 were isolated from surgical intensive care unit,and 53 strains were from male patients.All patients infected by S.maltophilia had received antibiotic therapy before the strains were isolated.At least three kinds of antibiotics were used in 62.8％ of the patients.MLST analysis indicated that 49 isolates were assigned novel STs(STnewl-STnew38),with new combinations of allelic profiles.The largest cluster of isolates was ST23 (6 strains).PFGE showed that there was weak genetic linkage between S.maltophilia strains.The 78 isolates were divided into 58 groups.About 2.6％ (2/78) and 10.3％ (8/78) of these strains were resistant to levofloxacin and trimethoprim-sulfamethoxazole,respectively.All the strains were susceptible to minocycline.The prevalence of virulence genes Stmprl,Stmpr2,snf-1 and Smlt3773 locus was 79.5％ (62/78),93.6％ (73/78),94.9％ (74/78) and 48.7％ (38/78),respectively.Biofilm formation test indicated that the mean ability of biofilm formation was 0.51±0.44 in terms of D492.There was no significant difference between males and females.Conclusions All patients with Stenotrophomonas maltophilia infection had a history of antibiotic use and male patients were susceptible population.Stenotrophomonas maltophilia isolates showed high prevalence of virulence genes.No clonal dissemination was found in the same department of hospital.