Improving the enrichment procedure for Enterobacteriaceae detection.

Abstract:

:The current ISO standard method for detection of Enterobacteriaceae (21528-1:2004) includes enrichment in EE broth which has been shown to be inhibitory to some members of this family, notably Cronobacter spp. A shortened procedure omitting the EE broth has been proposed, however competition from Gram-positive flora may be detrimental to the effective recovery of low levels of target organisms in some sample matrices. In this study we investigated novel cost effective modifications, designed to improve ISO 21528-1:2004 for the detection of Enterobacteriaceae. Initial experiments used a worse-case scenario involving stressed Enterobacteriaceae strains known to grow poorly in laboratory media as well as representative background competitors from powdered milk. The interaction between the Enterobacteriaceae and their competitors was characterised and additives to enhance the growth of target strains over non-target strains were investigated. Supplementation of BPW with 40 microM 8-hydroxyquinoline, 0.5 gL(-1) ammonium iron(III) citrate, 0.1 gL(-1) sodium deoxycholate and 0.1 gL(-1) sodium pyruvate (BPW-S) improved the recovery of Enterobacteriaceae from artificially and naturally contaminated samples. This improvement of the pre-enrichment broth may also be of interest for methods designed to detect specific foodborne pathogens belonging to the Enterobacteriaceae (e.g. Salmonella spp., Cronobacter spp.) that require a pre-enrichment step in BPW.

journal_name

Food Microbiol

journal_title

Food microbiology

authors

Weber C,Stephan R,Druggan P,Joosten H,Iversen C

doi

10.1016/j.fm.2009.03.010

subject

Has Abstract

pub_date

2009-09-01 00:00:00

pages

565-72

issue

6

eissn

0740-0020

issn

1095-9998

pii

S0740-0020(09)00065-3

journal_volume

26

pub_type

杂志文章