改良Hodge试验检测肠杆菌科细菌中碳青霉烯酶的研究

Detection of carbapenemase in enterobacteriaceae with modified Hodge test

目的用改良Hodge试验（MHT）检测肠杆菌科细菌碳青霉烯酶的产生，了解碳青霉烯酶基因分布。方法从浙江大学医学院附属第二医院、浙江省东阳市人民医院、北京医院和四川大学附属华西医院4家医院收集3718株肠杆菌科细菌，用纸片法检测细菌对厄他培南的敏感性，用MHT检测碳青霉烯酶的产生情况，并用PCR扩增常见的碳青霉烯酶基因。结果4家医院的肠杆菌科细菌对厄他培南的不敏感率为3．04％（113／3718），上述4家医院的不敏感率依次为5．09％、2．15％、2．59％和1．72％。MHT的总阳性率为2．29％（85／3718），4家医院的阳性率依次为4．73％、1．21％、1．06％和1．58％。113株厄他培南不敏感菌株中，MHT阳性82株，阴性31株。85株MHT阳性菌株中，82株对厄他培南耐药或中介耐药，仅有3株敏感。82株MHT阳性、厄他培南不敏感的菌株中，肺炎克雷伯菌碳青霉烯酶（KPC）基因阳性65株，亚胺培南水解酶（IMP）基因阳性15株，其中2株KPC和IMP同时阳性，其他4株未扩增到常见碳青霉烯酶基因。31株MHT阴性、厄他培南不敏感的菌株和3株MHT阳性、厄他培南敏感的菌株均未扩增到常见碳青霉烯酶基因。结论MHT可有效地检测肠杆菌科细菌中的碳青霉烯酶，具有敏感性高、假阳性率低的特点。肠杆菌科细菌所产碳青霉烯酶主要为KPC，其次为IMP。

Objective To detect carbapenemase production in enterobacteriaceae by using modified Hodge test （MHT） and investigate the distribution of carbapenemase genes. Methods A total of 3 718 isolates from enterobacteriaceae were collected from 4 hospitals, including Second Affiliated Hospital of Zhejiang University, People＇ s Hospital of Dongyang, Beijing Hospital, and Huaxi Hospital of Sichuan University. Susceptibility of enterobacteriaceae to ertapenem was tested by K-B method. MHT was used to detect carbapenemase in enterobacteriaceae and the common earbapenemase genes were amplified by using PCR. Results The total resistance rate （resistance and intermediate resistance） of enterobacteriaceae to ertapenem was 3.04% （113/3718） and there were differences in resistance rate of enterobacteriaceae to ertapenem among 4 hospitals （ 5.09% , 2. 15 %, 2. 59%, and 1.72% , respectively）. Of the 3718 isolates, 2. 29% （85） were positive to MHT, and there were differences in positive rate to MHT among 4 hospitals （4. 73% , 1.21%, 1.06% , and 1.58% , respectively）. Of 113 non-susceptible isolates to ertapenem, 82 were positive to MHT and 31 were negative. Of 85 MHT-positive isolates, 82 were resistant or intermediate resistant to ertapenem and only 3 were susceptible. Of 82 MHT-positive and non-susceptible isolates to ertapenem, 65 were positive to KPC gene, 15 were positive to IMP gene （two of them were positive to both KPC and IMP）, and 4 were negative to all tested carbapenemase genes. Thirty-one MHT-negative and non- susceptible to ertapenem and 3 MHT-positive and susceptible isolates to ertapenem were negative to all tested carbapenemase genes. Conclusions MHT is used to detect carbapenemase in enterobacteriaceae with high sensitivity and low false positive rate. KPC gene is the most occurred gene to be dominant in the production of carbapenemase in enterobacteriaceae, and the IMP gene is also responsible to the genesis of carbapenemase in enterobacteriaceae..