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Detection and enumeration of Clostridium difficile in retail meat

Abstract number: P2037

Weese J.S., Avery B., Rousseau J., Reid-Smith R.

Objectives: Community-associated C. difficile infection appears to be an increasing problem and concern has been expressed about food as a source of infection. While studies have identified C. difficile in retail meat, the level of contamination has not been reported. The objectives of this study were to determine the prevalence and concentration of C. difficile spores in retail meat and to characterise recovered isolates.

Methods: Ground beef and ground pork were purchased from retail outlets in 4 Canadian provinces. Broth enrichment using a rinse of ground meat into CDMN broth with 0.1% sodium taurocholate and inoculation onto CDMN agar was used for qualitative analysis. Quantitative testing was performed using serial 10-fold dilutions of the rinses and inoculation onto CDMN agar. Ribotyping, toxinotyping and toxin gene PCR were performed on isolates.

Results:C. difficile was isolated from 27/230 (12%) samples overall; 14/115 (12%) ground beef and 14/115 (12%) ground pork (P = 1.0) For ground beef, 10/14 (69%) were positive on enrichment culture only while 2/14 (14%) were positive on both enrichment and direct culture and 2/14 (14%) were positive on direct culture only. Of the 4 ground beef samples that were positive on direct culture, 20 spores/g were present in two while 120 and 240 spores/g were present in one each. For ground pork, 10/14 (71%) were positive on enrichment culture only while 2/14 (14%) were positive on both enrichment and direct culture and 2/14 (14%) were positive on direct culture only. Of the 4 ground pork samples that were positive on direct culture, 20 spores/g were present in three while 60 spores/g were present in one. All samples that were positive on direct but not enrichment culture only contained 20 spores/g. Typing data are presented in the table.

Discussion: This is the first study to quantify C. difficile contamination in retail meat and the finding of low levels may be important. While the infectious dose for C. difficile is not known and may be variable between individuals, it is plausible that low numbers of spores are less relevant than larger numbers. Yet, this low level contamination should not be dismissed. The predominance of toxin variant strains in not surprising, and the finding on ribotype 078 which has been associated with CA-CDI and ribotype 027, an important epidemic strain, raise concerns. Further study of food as a source of infection in warranted.

SourceRibotypeToxinotypeToxin genesn (%)
Ground beef078VA+, B+, CDT+10 (71)
 027IIIA+, B+, CDT+1 (7.1)
 CIXA+, B+, CDT+1 (7.1)
 Not tested  2 (15)
Ground pork078VA+, B+, CDT+9 (64)
 027IIIA+, B+, CDT+1 (7.1)
 CIXA+, B+, CDT+1 (7.1)
 YIIIA+, B+, CDT+1 (7.1)

Session Details

Date: 16/05/2009
Time: 00:00-00:00
Session name: 19th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Helsinki, Finland, 16 - 19 May 2009
Presentation type:
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