Preprint Review Version 1 This version is not peer-reviewed

Phenotypic Assays for Detection of Extended Spectrum Β-Lactamases and Carbapenemases: A Laboratory Guide for Microbiologists

Version 1 : Received: 21 September 2018 / Approved: 24 September 2018 / Online: 24 September 2018 (08:57:40 CEST)

How to cite: Aruhomukama, D. Phenotypic Assays for Detection of Extended Spectrum Β-Lactamases and Carbapenemases: A Laboratory Guide for Microbiologists. Preprints 2018, 2018090448 (doi: 10.20944/preprints201809.0448.v1). Aruhomukama, D. Phenotypic Assays for Detection of Extended Spectrum Β-Lactamases and Carbapenemases: A Laboratory Guide for Microbiologists. Preprints 2018, 2018090448 (doi: 10.20944/preprints201809.0448.v1).

Abstract

This review aimed at defining and classifying extended spectrum β-lactamases, ESBLs and carbapenemases, summarizing the different phenotypic methods used to detect production of these enzymes in clinically significant gram negative bacteria and also describing the methods that discourse challenges mostly encountered during detection of these enzymes in microbiology laboratories with the purpose of formulating recommendations on best practice to screen for these enzymes. We conclude that the modified double disk synergy, MDDS is not only suitable for the confirmation of ESBL production after screening isolates with the cephalosporin/clavulanate combination disc diffusion or broth micro-dilution methods but also distinguishes ESBL production and over-expression of AmpC-derepressed mutants and as well serves as an indicator for AmpC screening. Furthermore, we suggest cefotaxime, ceftazidime and cefpodoxime (for testing using a single drug) as indicator antibiotics of choice for ESBL detection. The MDDS and cefoxitin/AmpC inhibitor combination disc method, using cloxacillin and phenylboronic acid can be used as screening tests for AmpC production and either the AmpC disc test, the disc approximation test or the modified three dimensional extract test as confirmatory tests for AmpC production. We also suggest that confirmation of carbapenemase production be done with the modified hodge test, using Klebsiella pneumoniae ATCC 700603 as the indicator organism or the modified carbapenem inactivation method. However, to differentiate between the different classes of carbapenemases, boronic acid and EDTA based methods (double-disk synergy tests and combined-disk tests) using imipenem, meropenem and ertapenem, in combination with 3-aminophenylboronic acid and ethylene diamine tetra acetic acid be used.

Subject Areas

Extended spectrum β-lactamases, AmpC Carbapenemases, Carbapenemases, Classification, Phenotypic Detection, Clinically significant bacteria

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Comment 1
Received: 24 September 2018
Commenter: Dickson Aruhomukama
Commenter's Conflict of Interests: I am the author of the paper
Comment: The article reviews and summarizes the different phenotypic methods used to detect production ESBLs and Carbapenemases in clinically significant gram negative bacteria and also describes the methods that discourse challenges mostly encountered during detection of these enzymes in the microbiology laboratories.
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