Study of the Potential Zoonotic Transmission of Clostridium difficile in Belgian Cattle Farms.

Introduction:
Zoonoses are infectious that can be transmitted between animals and humans through direct contact,
close proximity or the environment. Since domestic and food animals frequently test positive for the
bacterium, it seems plausible that C. difficile could be zoonotic. A former study showed that the
prevalence in veal calf aged less than 6 months was 22% while in adult cattle population, it was 6,9 %.
Purpose:
This study aimed to determine the prevalence and the epidemiology of C. difficile in cattle farms and
the possible spread of the bacterium among animals and farmers.
Methods:
A total of 176 faecal samples of cattle were collected from 5 different Belgian farms (south East
Belgium), from November 2015 to February 2016. A stool sample of each farmer was also requested.
Detection of C. difficile was performed by classical culture on C. difficile selective medium (cycloserine
cefoxitin fructose cholate). Isolates were characterised by PCR-ribotyping and Genotype Cdiff test
(Hain Lifescience), which allows the detection of all toxin genes, mutations in gyrA gene and the
deletion in the regulator gene tcdC. Toxic activity was confirmed by a cytotoxic assay on MRC-5 cells.
Results:
C. difficile was detected in 14/178 (7.9%) animal samples. Isolates were grouped into five different
types, including PCR-ribotype 015 (this ribotype is one the most encountered in hospitals in Belgium).
The other types were UCL46A, UCL24*, UCL24, UCL33. All of them were identified as toxigenic by
cytotoxicity assay and toxin genes profile. In contrast, none of the 5 farmers studied were positive for
the bacterium.
Significance:
Results obtained indicate that PCR-ribotypes commonly isolated from hospitalised patients are also
present in cattle, indicating an animal reservoir. However, a zoonotic transmission could be not
demonstrated in this preliminary study.