广州地区泛耐药铜绿假单胞菌的分子流行病学调查

Investigation on epidemiology of pan-drug resistant Pseudomonas aeruginosa in Guangzhou

目的调查广州地区4家医院2005年3月至2007年3月泛耐药铜绿假单胞菌株之间的同源性，了解是否有该耐药株暴发流行。方法用脉冲场凝胶电泳（PFGE）对134株泛耐药铜绿假单胞菌株进行分型，明确其是否为同一菌株的克隆。结果134株铜绿假单胞菌PFGE图谱分为56型，其中主要流行型A型有45株，主要在医院A的中心ICU传播流行。其余3家医院也存在各自的流行株，即B、C、D医院的流行株分别为B型、C型、D型，占各医院的总分离株数的22．6％（7／31）、33．3％（6／18）、31．6％（6／19）。克隆株Q型同时存在于B医院与D医院，B医院和C医院分别有1株菌与A医院的A型同源性在80％以上，其余菌株在各医院间无同源性。对A医院ICU环境、纤维支气管镜、呼吸机管道采样，未发现A型克隆株存在；但有6例携带A型克隆株的患者在调查时间里多次入住ICU的情况。耐药机制分析，42株A克隆产IMP-9金属β内酰胺酶，B、C、D克隆不产金属酶。结论在2年的调查中，广州地区4家大型医院均存在不同规模的泛耐药铜绿假单胞菌株克隆株传播，虽然未发现优势克隆株在4家医院大规模传播，但部分医院间已有共同的克隆株存在。加强对铜绿假单胞菌定植患者的监控可能是控制克隆株继续传播的关键。

Objective To analyze a potential outbreak mechanism of Pseudomonas eruginosa by investigating the homology of pan-drug resistance isolates （PDR） isolated in four hospitals of Guangzhou from March 2005 to March 2007. Methods The pulse-field gel lectrophoresis （PFGE） was used to detect134 strains of pan-drug resistant Pseudomonas eruginosa in four hospitals, and determined whether they were derived from the same clone. Results 134 strains were classified into 56 types based on PFGE pattern. Type A was the commonest clone among four hospitals, 45 strains belonged to type A, mainly spreaded in hospital A. The rest strains were identified：7 for type B, 6 for type C, 6 for type D, which were isolated from hospital B to hospital D, respectively. There were 40 strains classified for individual types. General comparison showed there was no a large clone existing in all four hospitals, though type Q clone appeared in hospital B and hospital D. One strain from hospital B and one strain from hospital C had 80% homology with type A from hospital A. The environment survey showed there was no clonal strain of type A found in hospital A, although various samples from respiratory therapy equipment, bronchoscopes and medical erosols were collected and cultivated for three times during the period. However, six patients arrying type A Pseudomonas aeruginosa had been admitted to the same ICU of hospital A for many times. Analysis of antimicrobial resistance of the common clone from four hospitals revealed that 42 of 43 type A of Pseudomonas aeruginosa produced IMP-9 metallo β-lactamase. The strains of type B, type C and type D didn＇t produced metallo β- lactamase. Conclusions The various degree of clonal spread of pan-drng resistance Pseudomonas aeruginosa had occurred in four hospitals individually in two years. There was also clonal spread among some hospitals.It is important to monitor the patients colonized with epidemic clones to prevent clonal spread.