整合子的临床分布及其与细菌耐药表型相关性分析

Clinical distribution of integron and its correlation with bacterial resistance phenotype

目的了解整合子阳性菌株在临床分离的常见病原菌中的分布情况,及其与细菌耐药表型的相关性,为控制医院感染提供依据。方法采用聚合酶链反应(PCR)扩增和琼脂糖凝胶电泳等方法,对宁波市李惠利医院2018年临床分离的400株常见病原菌进行第1、2和3类整合子筛查,并对整合子阳性和阴性菌株的耐药表型进行对比分析。结果 400株临床菌株中整合子阳性菌株为112例,阳性率为28%。其中第1、2类及同时阳性菌株分别为17.50%、4.75%和5.75%,没有筛选到第3类整合子;112株阳性菌株主要分布于大肠埃希菌、肺炎克雷伯菌、铜绿假单胞菌和鲍氏不动杆菌;可变区测序结果显示,大肠埃希菌携带耐药基因主要为aadA5和aacA4,肺炎克雷伯菌携带耐药基因主要为aadA2、blaOXA-30和dfrA17,铜绿假单胞菌携带基因主要为aadA5和aacA8;鲍氏不动杆菌主要携带基因为afrA12;37株整合子阳性肺炎克雷伯菌对磺胺甲噁唑/甲氧苄啶、庆大霉素、左氧氟沙星、妥布霉素的耐药性均高于整合子阴性菌株(P<0.05),16株整合子阳性的铜绿假单胞菌对妥布霉素的耐药性高于整合子阴性菌株(P<0.05),10株整合子阳性的鲍氏不动杆菌对磺胺甲噁唑/甲氧苄啶的耐药性高于整合子阴性菌株(P<0.05)。结论本地区临床菌株中整合子分离率较高,其中以第1和2类为主,主要分布于革兰阴性菌中,来源于呼吸和重症监护室(ICU)等院感易发科室,整合子的携带与宿主菌的耐药表型有着密切联系。

OBJECTIVE To understand the distribution of integron-positive strains in common clinical isolates of pathogens and observe its correlation with bacterial resistant phenotype so as to provide guidance for control of nosocomial infection. METHODS By means of polymerase-chain-reaction(PCR) and agarose gel electrophoresis, the Class 1, 2 and 3 integrons were screened for 400 common pathogenic bacteria isolated from Ningbo Li Huili Hospital in 2018, and the resistance phenotypes were observed between the intergron-positive strains and the integron-negative strains. RESULTS Among the 400 clinical strains, 112 were positive for integrons, the positive rate was 28%, 17.50% of which were Class 1, 4.75% were Class 2, and 5.75% were simultaneous positive strains;the Class 3 integrons were not screened. Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii were dominant among the 112 positive strains. The result of sequencing of variable region showed that the major resistance genes of E.coli were aadA5 and aacA4, the main resistance genes of K.pneumoniae were aadA2, blaOXA-30 and dfrA17, the main genes of P.aeruginosa were aadA5 and aacA8, the main genes of the A.baumannii were dfrA12. The drug resistance of the 37 strains of integron-positive K.pneumoniae to trimethoprim-sulfamethoxazole, gentamycin, levofloxacin and tobramycin were significantly higher than those of integron-negative strains(P<0.05);the drug resistance rate of the 16 strains of integron-positive P.aeruginosa to tobramycin was significantly higher than that of the integron-negative strains(P<0.05);the drug resistance rate of the 10 strains of integron-positive A.baumannii to trimethoprim-sulfamethoxazole was significantly higher than that of integron-negative strains(P<0.05). CONCLUSION The isolation rates of integrons in clinical strains are relatively high in this region, the Class 1 and 2 are dominant and mainly distribute in the gram-negative bacteria isolated from the departments at high risk of nosocomial infection such as respiratory medicine department and intensive care unit(ICU). The strains’ carrying with integrons is closely associated with the drug resistance phenotype of the host strains.