Luis G. Arroyo1; Anthony van Dreumel2; Reny Lothrop3; Henry Staempfli3; J. Scott Weese1
Clostridium difficile is an important enteropathogen in humans and several domestic animal species. It has been isolated and its toxin (s) detected in fecal samples of diarrheic and non-diarrheic dairy calves, yet its role in disease is still unclear. The role of this enteropathogen as a cause of disease in veal calves had not been investigated. The objective of this study was to describe the pathological findings of suspected C. difficile-associated gastroenteritis infection in veal calves and to characterize C. difficile isolates obtained from veal calves.
Six veal calves (age range: 1-18 weeks-old) were submitted from a veal farm operation over a 6 month period for postmortem examination. Gastrointestinal (GI) contents were tested by enzyme immunoassay (EIA) for C. difficile toxins A/B and C. perfringens enterotoxin, and screened for common enteropathogens associated with neonatal calf diarrhea, including enterotoxigenic E. coli, Salmonella spp. C. perfringens, rotavirus, coronavirus and parasites. Samples from only 2 calves were cultured for C. difficile. C. difficile toxins A and/or B were detected in intestinal contents of all calves and no other enteropathogens were identified. Macroscopic lesions were similar in all cases and consisted of fibrinous enteritis, colonic edema, entero-colitis and multiple hemorrhages, dehydration, and pulmonary congestion and edema. Histologically, there were focal areas of mucosal erosion and fibrino-cellular exudates, with colonies of clostridia-like bacilli present in the lumen and on the mucosal surface small intestine and abomasum. There was marked transmural edema and focal areas of hemorrhage in the lamina propria, with congested and thrombosed capillaries. Mesenteric lymph nodes were markedly congested and edematous.
Subsequently, an investigation was performed on the farm. Fecal samples were collected from 24 diarrheic calves at one time point for C. difficile culture. Three historic isolates recovered from diarrheic calves 4 years earlier from the same veal farm were included for molecular analysis. PCR-ribotyping was performed and isolates were screened for genes encoding toxins A (tcdA), B (tcdB) and binary toxin (cdtB).
Clostridium difficile was isolated from the 2 initial calves and 22/24 diarrheic calves. Five ribotypes were identified from the 27 isolates (3 historical, 2 post mortem calves and 22 from diarrheic calves), and all were toxigenic. Sixteen (57%) possessed genes tcdA and tcdB, while the remainder were variant strains. 9 (32%) only possessed genes encoding tcdB, while 2 (7.1%) possessed tcdB and cdtB genes. Overall, the genes encoding tcdA, tcdB and cdtB were present in 16 (59%), 27 (100%) and 2 (7%) strains, respectively.
This preliminary report supports the potential capacity of C. difficile to colonize and cause disease in several species. Further study of diarrheic and normal veal calves is required to elucidate the role of this enteropathogen as a cause of gastroenteritis and diarrhea in veal calves and as a zoonotic pathogen.