Elsevier

Food Microbiology

Volume 32, Issue 2, December 2012, Pages 448-451
Food Microbiology

Short communication
Development of a consensus method for culture of Clostridium difficile from meat and its use in a survey of U.S. retail meats

https://doi.org/10.1016/j.fm.2012.08.005Get rights and content

Abstract

Three previously described methods for culture of Clostridium difficile from meats were evaluated by microbiologists with experience in C. difficile culture and identification. A consensus protocol using BHI broth enrichment followed by ethanol shock and plating to selective and non-selective media was selected for use, and all participating laboratories received hands-on training in the use of this method prior to study initiation. Retail meat products (N = 1755) were cultured for C. difficile over 12 months during 2010–2011 at 9 U.S. FoodNet sites. No C. difficile was recovered, although other clostridia were isolated.

Highlights

► A standard protocol for Clostridium difficile culture from retail meats was established. ► 1755 retail meats were cultured for C. difficile over a 12 month period. ► No C. difficile was isolated from meat, although other Clostridium ssp. were common.

Introduction

Clostridium difficile is an important cause of infectious diarrhea in healthcare settings, usually following antimicrobial therapy. However, C. difficile infection (CDI) is an increasingly-recognized cause of diarrhea among people in community settings without recent inpatient hospital exposure (Centers for Disease Control and Prevention, 2008; Kutty et al., 2010; Lambert et al., 2009). Hypervirulent C. difficile strains have been associated with increased incidence and severity of CDI in healthcare settings (Deneve et al., 2009; McDonald et al., 2005); increases in community-associated CDI (CA-CDI) may be driven by other factors. C. difficile causes disease in food animals (Debast et al., 2009; Keel et al., 2007; Songer, 2004) and has been recovered from retail foods in several countries (de Boer et al., 2011; Harvey et al., 2011a, 2011b; Johnson et al., 2005; Metcalf et al., 2010; Rodriguez-Palacios et al., 2007; Songer et al., 2009), leading some to suggest that food may be a source for CA-CDI (Metcalf et al., 2010; Rupnik, 2007; Rupnik and Songer, 2010). Although several groups have reported the isolation of C. difficile from retail meats (Harvey et al., 2011a, 2011b; Rodriguez-Palacios et al., 2009; Rodriguez-Palacios et al., 2007; Songer et al., 2009; Weese et al., 2009), there is no consensus method for culture of C. difficile from meats or other food products. This study was designed to establish a consensus method for culture of C. difficile from meats, and to determine the prevalence of C. difficile contamination of selected retail meats in the United States using a standardized culture method.

Section snippets

Comparison of culture methods for C. difficile culture from meats

Several different culture methods were evaluated for recovery of C. difficile from spiked ground meat samples. Independently-acquired ground beef was inoculated using a single spore suspension at a rate of approximately 100 spores/gram in three laboratories with expertise culturing and characterizing C. difficile. The spore suspension was prepared as described previously (Bertolo et al., 2012), except that phase contrast microscopy was not performed. Three types of initial broth enrichment were

Selection of a consensus method for culture of C. difficile from meats

C. difficile was recovered from the spiked meat samples with each of the methods evaluated. The best recovery was observed after 3 and 5 days of enrichment in broth medium (Table 1). Recovery of C. difficile in BHIT broth without initial heat shock appeared to be better than in CDMN broth or in BHIT with initial heat shock (Table 1). A subsequent evaluation of BHI compared with BHIT demonstrated no added benefit of taurocholate on C. difficile recovery in the broth enrichment step (data not

Disclaimer

The findings and conclusions in this report are those of the author(s) and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

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Current affiliation: The Carter Center, Atlanta, GA, USA.

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