Performance of VITEK 2 ESBL confirmation test in a set of well characterised clinical isolates of E. coli, K. pneumonia, K. oxytoca and Enterobacter species. An alternative for double disc testing

Abstract number: P890

Debets-Ossenkopp Y.J., al Naiemi N., Lee S., Murk J.L., Mulder J.A., Vandenbroucke-Grauls C.M.J.E.

Objectives: Severe infections caused by ESBL-producing micro-organisms are becoming more common all over the world. Rapid and accurate ESBL detection has to be pursued by routine clinical laboratories in order to offer assistance in guided antibiotic therapy. Phenotypic ESBL confirmation tests must be performed on isolates that, based on initial antimicrobial testing, are suspected to produce ESBL. We evaluated the performance of the VITEK 2 ESBL confirmatory test on two sets of clinical isolates.

Methods: Strains; First set: 31 E. coli (ECO), 3 Klebsiella pneumoniae (KPN), 1 Klebsiella oxytoca (KOX), 19 Enterobacter spp., ESBL positive (+) and 7 Enterobacter spp. ESBL negative (-) confirmed by molecular methods. Second set: 50 Enterobacter spp. ESBL(-) or (+), phenotypic confirmation with Double Disk Synergy Test (DDST), Double Disk Combination Test (DDCT) and ESBL E-test. Confirmatory tests: VITEK 2 ESBL card (in conjunction with VITEK 2 GNS N048), DDST, DDCT and E-test cefepime.

Table 1.

Results: see Table 1. Three out of 31 ECO were misidentified (2/3 SHV-12, 1/3 CTXM-2) with VITEK 2 ESBL test as well as with DDST, DDCT and E-test. All Enterobacter isolates ESBL (+) strains, that were confirmed by PCR and sequencing and/or by phenotypic confirmation, were correctly identified with the VITEK 2. One sequenced Enterobacter spp. ESBL (-) was false positive with the VITEK 2. In 13 out of 40 ESBL (-) strains (phenotypic confirmation), VITEK 2 was positive.

Conclusion: For the ECO, KPN the VITEK 2 ESBL test performed as well as the DDST, DDCT and E-test. For Enterobacter isolates performance of the VITEK 2 ESBL test needs further evaluation.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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