质粒介导的DHA型AmpC酶在肺炎克雷伯菌中的表达及对耐药性的影响

Impact of Expression of DHA AmpC β-Lactamases Mediated by Plasmid on Antibiotics Susceptibility of Clinical Isolates of Klebsiella pneumoniae

目的研究质粒介导的DHA型AmpC酶在肺炎克雷伯菌中的基因表型及耐药性。方法根据美国临床实验室标准协会(CLSI)的标准,用琼脂稀释法检测MIC值和K-B法确证ESBLs,利用3-氨基苯酚硼酸对AmpCβ-内酰胺酶(AmpC酶)的抑制作用检测肺炎克雷伯菌的AmpC酶表型;用基因芯片技术及聚合酶链反应(PCR)检测ESBLs与AmpC酶的基因型。结果DHA型AmpC酶肺炎克雷伯菌同时具有产超广谱β-内酰胺酶(ESBLs)为94.2%,以DHA+TEM+SHV的基因表型最多38.3%;AmpC酶肺炎克雷伯菌的MIC50均<0.25μg/ml、MIC90均<0.5μg/ml,该类菌对头孢他啶的耐药率(85.7%)高于对头孢噻肟的耐药率(60.0%),但MIC50和MIC90基本相同;34株产酶菌的耐药基因经质粒接合试验,分别有14株接合成功,5株在头孢噻肟和头孢西丁两种选择性平皿培养基中同时接合成功,2株在和头孢西丁平皿培养基中接合成功,7株在头孢噻肟平皿培养基中接合成功。结论解放军总医院质粒介导的DHA型AmpC酶,在肺炎克雷伯菌中以DHA+TEM+SHV的基因表型为主,同时具有ESBLs占94.1%;41.2%的可以将耐药质粒结合给大肠埃希菌。

OBJECTIVE To investigate the prevalence of DHA AmpC β-lactamases mediated by plasmid in Klebsiella pneumoniae in China, METHODS Antimicrobial susceptibility test was conducted by the methods of double agar dilution and ESBLs confirmatory in K-B method according to the criteria of guidelines of CLSI, AmpC β- lactamases were detected on the basis that AmpC β-1actamases could be inhibited by 3-aminophenylboronic acid （APB）. Gene chip technology and PCR were used to detect ESBLs and AmpC gene. RESULTS Among total 34 isolates of K. pneumoniae 32 （94. 1%） produced AmpC β-1actamases and ESBLs. The most common （38.3%） were types DHA and TEM and SHV. MIC50 and MIC90 of all strains to all tested antimicrobial agents were lower than 34 strains tested 0, 25μg/ml and 0.5μg/ml. Fourteen strains AmpC and ESBLs were conjugated successfully, CONCLUSIONS DI-IA AmpC β-lactamases mediated by plasmid are the most common in K. pneumoniae in General Hospital of PLA of China. The most common （38, 3%） are types DHA and TEM and SHV. Fourteen （41.2%） strains can be spreaded by plasmid,