奇异变形菌中整合子分布及耐药性分析

Analysis of integron distribution and drug resistance in Proteus mirabilis

目的了解院内奇异变形菌中各类整合子的携带分布情况、阳性菌株可变区基因盒类型以及其与宿主菌耐药表型的相关性,从而为临床治疗和院内感染控制提供参考。方法采用PCR扩增和琼脂糖凝胶电泳等方法,将本院2016年1月—2018年12月份从临床标本中分离得到的150株奇异变形菌进行第1、2和3类整合子的筛选,并对整合子阳性菌株可变区进行测序分析以及宿主菌的耐药性进行相关性分析。结果 150株奇异变形菌中携带整合子的菌株共有91株,阳性率为60.7%,其中第1类整合子阳性菌株有30株,占20.0%;第2类整合子阳性菌株22株,占14.7%;同时携带第1和2类菌株39株,占26.0%;未筛出第3类整合子;在91株整合子阳性菌株中,86株可变区出现扩增产物条带,其余5株可变区未见扩增产物;第1类整合子阳性菌株可变区携带的耐药基因盒主要为AadA2、DfrA32,第2类整合子阳性菌株可变区携带耐药基因盒主要为DfrA1;可变区携带AadA2的菌株对庆大霉素和妥布霉素的耐药率显著高于整合子阴性菌株(P<0.01),可变区携带DfrA1或DfrA32的菌株对复方磺胺甲噁唑(即甲氧苄啶/磺胺甲噁唑)的耐药率也明显高于整合子阴性菌株(P<0.01);91株整合子阳性菌株对氨苄西林/舒巴坦、复方磺胺甲噁唑、环丙沙星、庆大霉素、头孢曲松、妥布霉素和左氧氟沙星的耐药率均显著高于整合子阴性菌株(P<0.01)。结论临床分离的奇异变形菌携带整合子的比例较高,其可变区所携带的耐药基因主要为编码氨基糖苷类和甲氧苄氨嘧啶类抗菌药物的基因,整合子的携带与宿主菌产生的耐药性呈高度相关。

Objective To understand the distribution of integrons in Proteus mirabilis, the types of variable region gene cassettes of positive strains, and their correlation with drug resistance phenotypes of host bacteria, so as to provide references for clinical treatment and nosocomial infection control. Methods Using PCR amplification and agarose gel electrophoresis, 150 strains of Proteus mirabilis isolated from clinical specimens from January 2016 to December 2018 were screened for the class 1,2 and 3 integrons. Sequencing analysis of variable regions of integronpositive strains and correlation analysis of drug resistance of host strains were carried out. Results There were 91 strains carrying 150 integrons in Proteus mirabilis. The positive rate was 60.7%, among which 30 strains were the first type of integron positive strains, accounting for 20%, 22 strains of the second type of integron positive strains, accounting for 14.7%, 39 strains carrying the first and the second type at the same time, accounting for 26%. No type 3 integrons were screened out. Among the 91 integron-positive strains, 86 mutant regions showed amplification product bands, and the other five strain regions showed no amplification products. The resistance gene cassettes carried by the variable region of the first type of integron positive strains were mainly AadA2 and DfrA32, and the variable region carrying the resistance class of the second type of integron positive strain was mainly DfrA1. The strain carrying the AadA2 in the variable region was celebrated. The resistance rate against gentamicin and tobramycin was significantly higher than that of the integron-negative strain(P<0.01), and the resistance rate of the strains with DfrA1 or DfrA32 to the compound sulfamethoxazole was also significantly higher than that of the strains without integrons(P<0.01). The resistance rates of 91 integron-positive strains to ampicillin/sulbactam, compound sulfamethoxazole, ciprofloxacin, gentamicin, ceftriaxone, tobramycin, and levofloxacin were significantly higher than those without integrons(P<0.01). Conclusion The clinically isolated Proteus mirabilis had a higher proportion of carrying integrons, and the drug resistance genes carried in the variable region were mainly genes encoding aminoglycosides and trimethoprim antibacterial drugs. The host bacteria of the integrons and the resulting resistance was highly correlated.