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The Journal of the Japanese Society for Clinical Microbiology |
Biblioraphy Information
| ArticleTitle |
Evaluation of ertapenem disks in modified Hodge test for detection of carbapenemases in Gram-negative bacteria |
| Language |
J |
| AuthorList |
Tatsuki Mura1), Kumiko Kawamura1), Yoshichika Arakawa2) |
| Affiliation |
1) Department of Pathophysiological Laboratory Science, Nagoya University Graduate School of Medicine
2) Department of Bacteriology, Nagoya University Graduate School of Medicine |
| Publication |
J.J.C.M.: 25 (1), 42-51, 2014 |
| Received |
July 1, 2014 |
| Accepted |
September 16, 2014 |
| Abstract |
The aim of this study was to evaluate the performance of ertapenem (ERT) disk in modified Hodge test (MHT) for detection of carbapenemase-producing Gram-negative bacteria. A total of 100 genotypically well-characterized carbapenem-resistant Gram-negative bacteria and forty non-carbapenemase-producers were used in this study. Sensitivity rates for ERT disks, imipenem disks, and meropenem (MEPM) disks were 93%, 82% and 83%, respectively. Although ERT disks partially failed to detect carbapenemase-producers in Pseudomonas sp. (3 of 27 isolates), Acinetobacter sp. (2 of 19 isolates), OXA-23 type β-lactamase producers (1 of 4 isolates) and VIM-1 type β-lactamase producers (1 of 1 isolates), ERT disks showed the best sensitivity for detecting carbapenemase-producers co-producing other classes of β-lactamases, such as NDM-1 type β-lactamase-producing Enterobacteriaceae isolates. The specificity rate (88.9%) of ERT disks was slightly lower than that (95.6%) of MEPM disks, since false detection of carbapenemase production was observed in some non-carbapenemase-producing isolates, such as CTX-M-type ESBL-producing Enterobacteriaceae and P. aeruginosa overexpressing AmpC-type β-lactamase. However, incorporation of inhibitors such as clavulanic acid and cloxacillin to ERT disks increased the specificity of ERT disks. These techniques seem to be effective for the detection of carbapenemase even in bacterial isolates co-producing ESBL and/or AmpC-type β-lactamases. As in all phenotypic tests, interpretation is subjective and requires some experience, but ERT disks have the advantage of being easy to interpret compared to other disks. Rapid and accurate phenotypic detection of carbapenemase-producers is important for epidemiological purposes and for inhibiting the spread of resistant strains by implementing specific infection control measures. In conclusion, MHT using ERT disks would be useful for detecting carbapenemase-producers in the daily clinical laboratory workflow. |
| Keywords |
modified Hodge test |
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