The laboratory diagnosis of Pseudomonas aeruginosa that produce metallo-beta-lactamases in a Dutch tertiary care centre

Akke Bij, M (Mark) de Mol, Mireille van Westreenen, Wil Goessens, JDD Pitout

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Abstract

Background: The laboratory detection of Pseudomonas aeruginosa that produce metallo-beta-lactamases (MBLs) is not well defined in regions with a low prevalence of these enzymes. We report a study that developed ethylenediaminetetraacetic acid (EDTA) disk screen tests using doripenem, imipenem and meropenem and investigated the prevalence of these enzymes among clinical isolates of imipenem-resistant P. aeruginosa in Rotterdam during 2008-2009. Methods: Using strains with well-characterized beta-lactamases and the Clinical and Laboratory Standards Institute (CLSI) disk methodology similar to extended-spectrum beta-lactamase (ESBL) detection, inhibition zone diameters were determined in tests with doripenem, imipenem, and meropenem, alone and in combination with 370 mu g of EDTA. These tests were compared with the MBL E-test. A positive test was a >= 5 mm increase in zone diameter in the presence of EDTA. Results: The imipenem EDTA disk screen test showed a sensitivity of 100% and a specificity of 90% in 96 recent clinical isolates. Imipenem in combination with doripenem performed better than imipenem alone, meropenem, and the MBL E-test (sensitivity of 100%; specificity of 95%). The majority of clinical isolates were isolated from patient respiratory specimens. Of the 96 imipenem-resistant P. aeruginosa isolated, 35 (36%) were positive for bla(VIM) genes. Conclusions: The EDTA imipenem/doripenem disk test showed accurate and reproducible results with excellent sensitivity and specificity. It is simple to perform and interpret and can be easily introduced into the workflow of a clinical laboratory to screen for MBLs in imipenem-resistant P. aeruginosa. Due to its high specificity the test is also suitable for regions with a low prevalence of these enzymes.
Original languageUndefined/Unknown
Pages (from-to)596-602
Number of pages7
JournalScandinavian Journal of Infectious Diseases
Volume43
Issue number8
DOIs
Publication statusPublished - 2011

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  • EMC MM-04-28-01

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