改良Hodge试验检测肠杆菌科IMP型碳青霉烯酶的性能评价

目的探讨改良Hodge试验（modified Hodge test，MHT）在检测肠杆菌科细菌IMP型碳青霉烯酶中的应用价值。方法以VITEK2Compact全自动细菌鉴定及药敏系统进行细菌鉴定和药敏试验，筛选2010-2012年非重复临床分离的碳青霉烯类药物敏感性降低的肠杆菌科细菌，以MHT进行产碳青霉烯酶表型确证试验，PCR检测碳青霉烯酶blaKPC、blaIMP；6如VIM、blaoXA-48及blandm-1基因型，阳性结果进行测序并Blast比对确定基因型。以基因测序结果为金标准，分析统计MHT检测肠杆菌科碳青霉烯酶的各项性能指标。结果本实验共收集62株碳青霉烯类药物敏感性降低的肠杆菌科细菌，包括肺炎克雷伯菌42株，阴沟肠杆菌12株，大肠埃希菌5株，产酸克雷伯菌3株；MHT检测阳性51株，占总株数的82．26％，肺炎克雷伯菌、阴沟肠杆菌、大肠埃希菌、产酸克雷伯菌分别占各自菌种的比例为83．33％，75．0％，80．0％，100．0％；经PCR扩增并测序证实27株为产IMP-4型菌株，20株为产IMP-8型菌株，其他15株为碳青霉烯酶阴性菌株；MHT检测肠杆菌科细菌产IMP型碳青霉烯酶的灵敏度为97．87％％，特异性为66．67％，阳性预测值为90．2％，阴性预测值为90．91％，检验效能为90．32％。结论MHT检测肠杆菌科细菌产IMP型碳青霉烯酶具有良好的灵敏度，但特异性偏低，建议进一步使用分子生物学技术检测碳青霉烯酶肠杆菌科细菌基因型。

Performance of modified Hodge test for the detection of Enterobacteriaceae that produce IMP carbapenemase

Objective To evaluate the application value of-modified Hodge test （MHT） for the detection of Enter- obacteriaceae that produce IMP carbapenemase. Methods The bacterial identification and antibiotic susceptibility was operated by VITEK 2 Compact automated system. The non-repeat clinical isolates of Enterobacteriaceae with reduced susceptibility to carbapenems were collected between 2010 and 2012. The phenotypes of carbapenemases was detected by MHT. The blaKec, blaIMP , blaVIM, blaoxn 48 and blaNDM-1 gene were amplified by PCR, then positive results were se quenced and blasted to determine genotype. Since the results of gene sequencing as the gold standard,the performance of MHT for the detection of carbapenemase in Enterobacteriaceae was calculated based on sequencing result. Results Six- ty-two Enterobacteriaceae with reduced susceptibility to carbapenems were collected, including 42 K. pneumoniae, 12 E. cloacae,5 E. coli and 3 K. oxytoca. The MHT detected 51 positive in study strains,account for 82.26% of the total strain. The proportion of K. pneumoniae,E, cloacae,E, coli,K, oxytoca was 83.33% ,75.0% ,80.0% and 100.0% ac- counted for each strain. The 27 IMP-4 and 20 IMP-8 carbapenemase producing isolates were confirmed by PCR amplifi- cation and sequencing, the other 15 isolates were confirmed carbapenemase-negative strains. The sensitivity, specificity, positive predictive value, negative predictive value and test power of MHT was 97.87 %,66.67%,90.2%, 90.91%and 90.32% for the detection of IMP carbapenemase among Enterobacteriaceae with decreased susceptibility to carbapene- ms. Conclusion MHT revealed great sensitivity but low specificity for IMPs,molecular biology to detect carbapene- mase genotype were recommend for the further detection of carhapenemase-producing Enterobacteriaceae.