Multi‐centre evaluation of a phenotypic extended spectrum β‐lactamase detection guideline in the routine setting. (23rd January 2012)

• Record Type: Journal Article
• Authors: Platteel, T. N.; Cohen Stuart, J. W.; de Neeling, A. J.; Voets, G. M.; Scharringa, J.; van de Sande, N.; Fluit, A. C.; Bonten, M. J. M.; Leverstein‐van Hall, M. A.
• Is Part Of: Clinical microbiology and infection. Volume 19:Number 1(2013:Jan.)
• Page Start: 70
• Page End: 76
• Publication Date: 2012-01-23
• Subjects: Medical microbiology -- Periodicals; Diagnostic microbiology -- Periodicals; Communicable diseases -- Periodicals; Infection -- Periodicals; 616.01
• DOI: 10.1111/j.1469-0691.2011.03739.x
• Languages: English
• ISSNs: 1198-743X

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>This study aimed to evaluate the routine setting performance of a guideline for phenotypic detection of extended spectrum β‐lactamases (ESBLs) in Enterobacteriaceae, recommending ESBL confirmation with Etest or combination disc for isolates with a positive ESBL screen test (i.e. cefotaxime and/or ceftazidime MIC >1 mg/L or an automated system ESBL warning). Twenty laboratories submitted 443 Enterobacteriaceae with a positive ESBL screen test and their confirmation test result (74%<italic>Escherichia coli</italic>, 12%<italic>Enterobacter cloacae</italic>, 8%<italic>Klebsiella pneumoniae</italic>, 3%<italic>Proteus mirabilis</italic>, 2%<italic>Klebsiella oxytoca</italic>). Presence of ESBL genes was used as reference test. Accuracy of local phenotypic ESBL detection was 88%. The positive predictive value (PPV) of local screen tests was 70%, and differed per method (Vitek‐2: 69%, Phoenix: 68%, disc diffusion: 92%), and species (95%<italic>K. pneumoniae</italic>‐27%<italic>K. oxytoca</italic>). A low PPV (3%) was observed for isolates with automated system alarm but third‐generation cephalosporin MICs <2 mg/L. Local ESBL confirmation had a PPV and negative predictive value (NPV) of 93% and 90%, respectively. Compared with centrally performed confirmation tests, 7% of local tests were misinterpreted. Combination disc was more specific than Etest (91% versus 61%). Confirmation tests were not reliable for <italic>P. mirabilis</italic> and <italic>K. oxytoca</italic> (PPV 33% and 38%, respectively, although NPVs were 100%). In conclusion, performance of Etests could be enhanced by education of technicians to improve their interpretation, by genotypic ESBL confirmation of <italic>P. mirabilis</italic> and <italic>K. oxytoca</italic> isolates with positive phenotypic ESBL confirmation, and by interpreting isolates with a positive ESBL alarm but an MIC <2 mg/L for cefotaxime and ceftazidime as ESBL‐negative.</p> </abstract>