产AmpC酶的克雷伯菌药敏结果分析及质粒介导的AmpC和ESBLs耐药基因检测

Analysis of the drug susceptibility of Klebsiella and plasmid-medited of AmpC and ESBLs

目的了解克雷伯菌的耐药性及产AmpC菌株同时产ESBLs药敏的变化。方法采用Vitek60型和Vitek32型、纸片扩散法(KB法)测定42株产AmpC酶同时产ESBLs克雷伯菌的药敏结果,并与24株产AmpC酶但不产ESBLs克雷伯菌和138株不产AmpC酶但产ESBLs的克雷伯菌药敏结果对比分析;采用PCR分析产AmpC酶但不产ESBLs肺炎克雷伯菌的AmpC基因型。结果产AmpC不管是否产ESBLs的克雷伯菌对亚胺培南敏感,对其他抗生素均有不同程度的耐药;单纯产ESBLs时,第四代头孢菌素如头孢吡肟对其活性较好,但产AmpC酶同时产ESBLs时,令头孢吡肟几乎失去活性。肺炎克雷伯菌产AmpC酶但不产ESBLs的20株菌中7株检出blaDHA基因,占35%,1株检出blaMIR基因,占5%。另外同时产AmpC酶和ESBLs的20株肺炎克雷伯菌中100%检出blaTEM基因,90%检出blaCTX-M-1基因,100%检出blaSHV基因,85%检出blaDHA基因,15%检出blaMIR基因,90%检出不同的氨基糖苷类修饰酶基因。结论克雷伯菌产AmpC酶和同时产ESBLs的耐药性比单纯产AmpC酶的耐药性更高、更显著;肺炎克雷伯菌产Am-pC酶的主要基因型为DHA,对同时存在2～6种不同类型耐药基因的克雷伯菌,碳青霉烯类药物亚胺培南的体外活性最好。

Objective To investigate the drug resistance of Klebsiella and the durg susceptibilitiy variation of ESBLs and AmpC simultaneously-producing stains. Methods The drug susceptibility of 42 AmpC and ESBLs producing Klebsiella were detected by Kirby-Bauer motheds, Vitek 60 and Vitek 32 method. And the results were compared with those of 24 Klebsiella producing AmpC but nonproducing ESBLs and those of 138 Klebsiella producing ESBLs but nonproducing AmpC. The genotypes of AmpC were identified by PCR. Results All AmpC-producing Klebsiella were susceptible to imipenem and different degree of resistance to other tested antibiotics. The fourth generation of cephlosporin such as cefepime had potent activities to Klebsiella, but had little activity against Klebsiella simultaneously-producing AmpC and ESBLs. Of 20 strains of Klebsiella producing AmpC but nonproducing ESBLs, 7 strains were detected blaDHA gene and 1 strain with blaMIR gene; blaTEM genes were amplified in 20 strains （100%）, blaCTX-M-1 genes were detected in 18 strains （90%）, blasHv genes were examined in 2 strains （10%）, blaDHA genes in 17 strains （85%）, blaMIR genes in 3 strains （15%） and three types of AMEs-encoding genes were tested in 18 strains （90%）. Conclusions The antimicrobial resisitant rates of Klebsiella simutaneouly-producing AmpC and ESBLs are higher than that to Klebsiella producing AmpC but nonproducing ESBLs. The genotypes of Klebs＆lla producing AmpC are mainly DHA type. Imipenem is the first choice of the antibiotics against KlebsieUa carrying 2-6 kinds of resistance genes in clinic.