Performance of modified Hodge test on the detection of carbapenemase among Enterobacteriaceae
10.3760/cma.j.issn.1009-9158.2010.12.004
- VernacularTitle:改良Hodge试验检测肠杆菌科细菌碳青霉烯酶的性能评估
- Author:
Qiwen YANG
;
Rui ZHENG
;
Hui WANG
;
Minjun CHEN
;
Yingchun XU
;
Weiyuan WU
;
Yunsong YU
;
Ziyong SUN
;
Mingqing TONG
;
Rong ZHANG
;
Kang LIAO
;
Bin CAO
;
Xinhong HUANG
;
Lianna ZHU
;
Yuxing NI
;
Ping JI
;
Chao ZHUO
;
Danhong SU
;
Hong FAN
;
Wenen LIU
;
Xiuli XU
;
Hongli SUN
;
Xiuli XIE
- Publication Type:Journal Article
- Keywords:
Enterobacteriaceae;
beta-Lactamases;
Bacterial proteins;
Carbapenems;
Microbial sensitivity tests
- From:
Chinese Journal of Laboratory Medicine
2010;33(12):1122-1127
- CountryChina
- Language:Chinese
-
Abstract:
Objective To evaluate the performance of modified Hodge test on the detection of carbapenemases among Enterobacteriaceae with decreased susceptibility to carbapenems. Methods Fortynine Enterobacteriaceae isolates with decreased susceptibility to carbapenems ( MIC of imipenem, meropenem or ertapenem was ≥ 2 μg/ml ) were collected from 16 teaching hospitals from 2004 to 2008. MICs of imipenem, meropenem and etapenem were determined by agar dilution method. Carbapenemases were detected by modified Hodge test. Carbepenemase-causing positive results and AmpCs-causing positive results were differentiated by phenyl boronic acid and oxacillin. Beta-lactamases encoding genes including blaNDM-1were detected by PCR and sequencing. Results Thirty-six of 49 isolates were non-susceptible to imipenem (MIC >4 μg/ml), 31 were non-susceptible to meropenem (MIC > 4 μg/ml) and 47 were non-susceptible to ertapenem (MIC > 2 μg/ml). Twenty-three isolates showed positive modified Hodge test result, including 9 weak-positive results and 14 strong-positive results. Through PCR detection and sequencing, 2 out of 9 isolates showing weak-positive results carried blaKPC-2 and other 7 did not carry any carbapenemase genes but AmpCs/ESBLs genes. Among the 14 isolates showing strong-positive results, 4 carried blaKPC-2, 8 carried blaIMP-4 and 2 caried blaIMP-8. All 26 isolates with negative modified Hodge test result didn't carry any carbapenemase genes. No isolate carried blaNDM-1. Carbapenemases genes PCR detection was regarded as a gold standard, and the sensitivity, specificity, positive predictive value and negative predictive value of modified hodge test was 100%, 79%, 70% and 100% on the detection of carbapenemases among Enterobacteriaceae with decreased susceptibility to carbapenems. Conclusions Modified Hodge test revealed great sensitivity but showed a few false positive results. True and false positive results can be effectively differentiated by phynel boronic acid and oxacillin.
