四家長庚醫院加護病房中會產生超廣效性乙醯胺酶的Klebsiella pneumoniae及Escherichia coli之分子流行病學探討

Objective: Members of the Enterobacteriaceae that were able to produce extended-spectrum β-lactamases (ESBLs) have aroused global concerns regarding their multiple drug resistance. In Taiwan, the prevalence rates of ESBL-producing Klebsiella pneumoniae and Escherichia coli were relatively higher than those from other countries in Europe and American. During 2001-2004, analysis of the isolation rates of these resistant bacteria from four Chang Gung Memorial Hospitals (CGMHs) revealed that the prevalence rates of such resistant pathogens were much higher among intensive care units (ICUs) than those among general wards. To further elucidate the extent and mode of dissemination of these ESBL-producing isolates, a total of 130 K. pneumoniae and 143 E. coli isolates were collected from ICUs between January and June 2005. The genetic relatedness of these isolates and the genotypes of the ESBLs were investigated. The results revealed that SHV-and CTX-M-type ESBLs were the two major ESBL types with CTX-M-type ESBLs (80.9%) being the most prevalent. Among them, the most common ESBLs were CTX-M-14 (39%), CTX-M-3 (20%), and SHV-12 (14%). ESBL types were more diverse in K. pneumoniae than in E. coli. A total of 14 ESBL types (9 SHVs and 5 CTX-Ms) were found in K. pneumoniae, while 8 ESBLs (2 SHVs and 6 CTX-Ms) were found in E. coli. In K. pneumoniae, the prevalence rate of CTX-M-type ESBLs (both 75%) was higher than that of SHV-type ESBLs in northern CGMHs, while in southern CGMH (Kaohsiung), the prevalence rate of SHV-type ESBLs (60%) was higher than that of CTX-M-type ESBLs. In E. coli, CTX-M-type ESBLs were the most prevalent among all CGMHs (87.5%-100%, average 93.7%). Molecular typing analysis demonstrated 75 genotypes in K. pneumoninae and 115 genotypes in E. coli, suggesting the high genetic diversity in both organisms. However, small clusters of genotypes were also noted. In summary, ESBL-producing bacteria differed in both genotypes and prevalence rates between the two ends of Taiwan. Continuous surveillance of the prevalence and changing epidemiology among the ESBL-producing populations appears necessary.