CLINICAL USE OF MOLECULAR EPIDEMIOLOGY FOR NOSOCOMIAL IMIPENEMRESISTANT PSEUDOMONAS AERUGINOSA INFECTIONS

为探讨基因分型在铜绿假单胞菌医院感染中的临床应用，我们对本院外科病房分离的耐亚胺培南铜绿假单胞菌(IRPA)进行了基因分型和血清学分型。对1987~1998年间临床分离的428株铜绿假单胞菌分别用玻片凝集试验和脉冲场凝胶电泳法进行血清学分型和基因分型。根据NCCLS指南确定亚胺培南的耐受性。总体而言，IRPA感染的发生率为21.5%。1990年、1991年和1994年IRPA感染的年发病率特别高(34-47%)。从血清学角度看，1990-1991年间F群流行，1994年B群流行。在PFGE分析中，F组菌株显示出相同的模式，而B组菌株则检测到三种模式，表明这些暴发是医院感染的肆虐。1995年后，通过合理使用碳青霉烯类抗生素，IRPA感染发生率下降(14.6%)，血清学分型和PFGE分析均未发现明显暴发。然而，从数字化的PFGE模式中得出的计算机树状图显示，一些零星的医院感染仅限于“病人对病人”。尽管可以提倡用血清分型来检测医院感染的暴发。PFGE可用于院内感染暴发前“病人对病人”有限感染的调查。

To elucidate the clinical use of genotyping for nosocomical infections of Pseudomonas aeruginosa (P.aeruginosa), we examined genotyping and serotyping of imipenem-resistant Pseudomonas aeruginosa (IRPA) isolated in our surgical ward. In 428 P.aeruginosa strains clinically isolated from the patients between 1987 and 1998, serotyping and genotyping were performed by the slideagglutination test and pulsed-field gel electrophoresis (PFGE), respectively. Suseeptibility ageinst imipenem was determined according to the NCCLS guidelines. Overall, the incidence of IRPA infection was 21.5%. The annual incidences of IRPA infections were particularly high in 1990, 1991 and 1994 (34-47%). Serologically, group-F strains were prevalent between 1990 and 1991, and group-B strains in 1994. In PFGE analysis, the identical pattern was shown in group-F strains, and three patterns were detected for group-B strains, suggesting that these outbreaks raged as nosocomial infections. By appropriate use of carbapenem antibiotics after 1995, the incidence of IRPA infections was reduced (14.6%) and neither serotyping nor PFGE analysis detected distinct outbreaks. However, computed dendrogram derived from digitized PFGE patterns revealed some sporadic nosocomial infections limited to "patient-to-patient". Although serotyping can be advocated for detecting outbreaks of nosocomial infections. PFGE may be useful for survey of "patient-to-patient" limited infection before outbreaks of nosocomial infections.