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Evaluation of Double-Disk Potentiation and Disk Potentiation Tests Using Dipicolinic Acid for Detection of Metallo-β-Lactamase-Producing Pseudomonas spp. and Acinetobacter spp
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| Zeitschriftentitel: | Journal of Clinical Microbiology |
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| Personen und Körperschaften: | , , , , |
| In: | Journal of Clinical Microbiology, 50, 2012, 10, S. 3227-3232 |
| Format: | E-Article |
| Sprache: | Englisch |
| veröffentlicht: |
American Society for Microbiology
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| Schlagwörter: |
| Zusammenfassung: | <jats:title>ABSTRACT</jats:title> <jats:p> Accurate detection of metallo-β-lactamase (MBL)-producing <jats:named-content content-type="genus-species">Pseudomonas</jats:named-content> spp. and <jats:named-content content-type="genus-species">Acinetobacter</jats:named-content> spp. became very important with the increasing prevalence of carbapenem-nonsusceptible clinical isolates. The performance of phenotypic MBL detection methods may depend on the types of MBL and the characteristics of the isolates. A high false-positive rate is a problem with EDTA-based MBL detection methods. We evaluated the performance of double-disk potentiation tests (DDPTs) and disk potentiation tests (DPTs) with dipicolinic acid (DPA) using 44 isolates of <jats:named-content content-type="genus-species">Pseudomonas</jats:named-content> spp. and <jats:named-content content-type="genus-species">Acinetobacter</jats:named-content> spp. producing IMP-1-like, VIM-2-like, and SIM-1 type MBLs. Also, we characterized <jats:named-content content-type="genus-species">P. aeruginosa</jats:named-content> isolates with positive imipenem (IPM)-DPA DDPT, but negative meropenem (MEM)-DPA DDPT, and determined possibility of improving a DDPT by using MacConkey agar. Among five different DDPT methods, the IPM-DPA 250-μg method showed the highest sensitivity (97.7%) and specificity (100%). Among four DPT tests, the highest sensitivity (100%) was shown by the IPM-EDTA 1,900-μg disk method, but the specificity was very low (11.4%). Five of six <jats:named-content content-type="genus-species">P. aeruginosa</jats:named-content> isolates with false-negative DDPTs with MEM-DPA 250-μg disks carried <jats:italic>bla</jats:italic> <jats:sub>IMP-6,</jats:sub> and the high level resistance to MEM (MIC ≥ 512 μg/ml) was reduced by the presence of phenylalanine arginine β-naphtylamide. Improvement of DDPTs was observed when MacConkey agar was used instead of Mueller-Hinton agar. In conclusion, DPA is a better MBL inhibitor than EDTA for detection of <jats:named-content content-type="genus-species">Pseudomonas</jats:named-content> spp. and <jats:named-content content-type="genus-species">Acinetobacter</jats:named-content> spp. with IMP-1-like, VIM-2-like, and SIM-1-type MBLs. In DPA DDPTs, IPM disks perform better than MEM disks when the isolates are highly resistant to MEM due to the overexpression of efflux pumps. </jats:p> |
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| Umfang: | 3227-3232 |
| ISSN: |
0095-1137
1098-660X |
| DOI: | 10.1128/jcm.00818-12 |