抑制法检测持续高产和质粒介导的AmpC β内酰胺酶

目的 探讨以苯基硼酸(Phenylboronic acid,PBA)和氟氯西林(Flucloxacillin,FCC)为抑制剂检测持续高产和质粒介导的AmpC β内酰胺酶(AmpC-BLA)的可靠性.方法 以PBA和FCC作为AmpC-BLA的抑制剂,采用双纸片增效试验、双纸片协同试验,分别检测阳性控制菌株阴沟肠杆菌(029M)、质粒介导的ACT-1型大肠埃希菌DHSa2919、MOX-1型肺炎克雷伯菌、LAT-2型大肠埃希菌,阴性控制菌株阴沟肠杆菌O29(野生型)、大肠埃希菌SHV-1、大肠埃希菌SHV-2、大肠埃希菌SHV-5、大肠埃希菌TEM-1、大肠埃希菌TEM-3、肺炎克雷伯菌SHV-18、大肠埃希菌ATCC25922和107株革兰阴性杆菌的AmpC-BLA,与头孢西丁三维试验(3-DT)进行比较,分析不同方法检测AmpC-BLA的准确度.结果 头孢西丁3-DT、PBA、FCC抑制试验检测4个阳性控制菌株和9个阴性控制菌株都获得了如期结果.检测107株肠杆菌科细菌的AmpC-BLA,3-DT阳性率24.3%(26/107),PBA、FCC双纸片增效试验阳性率分别为30.8%(33/107)、26.2%(28/107),PBA、FCC双纸片协同试验阳性率均为23.4%(25/107).接合试验有2株奇异变形杆菌和1株肺炎克雷伯菌阳性,为质粒型AmpCBLA.PBA和FCC双纸片增效试验检测诱导型AmpC-BLA有较高的假阳性,而双纸片协同试验的准确度高,与头孢西丁三维试验相比符合率均达99.1%.结论 PBA和FCC为抑制剂的双纸片协同试验,不管是检测持续高产型还是质粒介导的AmpC-BLA,均具有操作简单、实用、有效、准确等特点.

Inhibitor-based methods for detection of derepressed hyperproduction and plasmid-mediated AmpC β-lactamases

Objective To investigate the reliability of using inhibitors including Phenylboronic acid (PBA)and Fqucloxacillin(FCC)in detecting derepressed hyperproduction and plasmid-mediated AmpC B-lactamases.Methods PBA and FCC were chosen as inhibitors and double-disk potentiation method and double-disk synergy method were used to detect positive and negative control strains of AmpC β-lactamases and 107 clinical isolates for AmpC β-lactamases production.The positive control strains included E.cloacae (029M),plasmid-mediated ACT-1 type of E.coli DH5a2919,MOX-1 type of k pheumoniae,LAT-2 type of E.coil.The negative control strains included E.cloacae 029(wild-type),E.coli SHV-1,E.coli SHV-2, E.coil SHV-5,E.coli TEM-1,E.coli TEM-3,k peumoniae SHV-18 and E.coli ATCC25922.We compared the results above with the three dimensional test(3-DT)to observe the accuracy in detecting AmpC-BLA.Results 3-DT together with PBA and FCC based inhibition tests showed the 4 positive control strains and the 9 negative control strains were determined as expected.AmpC-BILA was detected in 107 clinical isolates ofEnterobacteriaceaes.The positive rate of3-DTmethod is24.3%.The positive rates ofPBA.FCC double-disk potentiation method and double-disk synergy method are 30.8%(33/107),26.2%(28/107) and 23.4%(25/107),respectively.The conjugate results in two strains of P mirabilis and one strain of K.peumoniae were positive.They were all plasmid-mediated AmpC-Bi.A.There Was a higher false positive when using PBA and FCC-based double-disk potentiation method to detect the induction type of AmpC-BLA, but the accuracy of double-disk synergy method was high.Compared with the 3-DT,the coincidence rate using PBA and FCC-based double-disk synergy method is 99.1%.Conclusions Using PBA and FCC as inhibitors in the double-disk synergy test is a accurate and reliable method to detect AmpC-BLA regardless of derepressed hyperproduction type or plasmid-mediated type.