No abstract

The incidence and severity of disease associated with toxigenic Clostridium difficile have increased in hospitals in North America from the emergence of newer, more virulent strains. Toxigenic C. difficile has been isolated from food animals and retail meat with potential implications of transfer to human beings. The objective of the present study was to determine the prevalence of toxigenic C. difficile in chickens and retail poultry meat in Texas. Seven C. difficile isolates were detected in fecal samples of 300 (2.3%) broiler chickens. Three cultivation procedures were evaluated for isolation of C. difficile from poultry meat and detected 1/32 (3.1%), 2/32 (6.2%), and 4/32 (12.5%) for the three procedures, respectively. Chicken and poultry meat isolates were characterized as toxinotype V and pulsed-field gel electrophoresis gel type-NAP7 or NAP7-variant. Susceptibilities to 11 antimicrobial agents in the current study suggested somewhat reduced resistance than reported for other meat or animal toxinotype V isolates.

A defined bacterial culture protective against Salmonella typhimurium cecal colonization in broiler chicks was derived utilizing a continuous-flow (CF) culture apparatus. Chicks receiving the CF culture in combination with a diet containing dietary lactose were protected against cecal colonization by S. typhimurium. The culture consisted of a mixture of gram-positive and gram-negative facultative and strictly anaerobic bacteria. The isolates were identified as Enterococcus avium, two strains of Enterococcus faecalis (designated A and B), Lactococcus lactis, Lactobacillus animalis, a Lactobacillus that could not be identified to species level (designated strain CMS), Citrobacter freundii, Escherichia coli, E. fergusonii, Bifidobacterium animals, and Propionibacterium acidipropionici. Results indicated that CF cultures can be used as a tool to identify bacteria which are antagonistic to S. typhimurium in the chick cecum.

A continuous-flow culture system was used to isolate and maintain a mixed culture of cecal bacteria from adult broilers composed of 29 bacterial strains representing 10 genera. Broiler chicks were treated with the mixed culture in the drinking water on the day of hatch and challenged orally with 10(4) Salmonella typhimurium 2 d after treatment. The experiment was repeated in four separate trials using newly hatched chicks. The concentration of propionic acid and total volatile fatty acid (VFA) in the cecal contents was determined 2 d after treatment and at 10 d of age. Compared with controls, the number of treated chicks that were cecal culture-positive for Salmonella decreased (P < .01) in each of the trials. Additionally, the number of Salmonella in the cecal contents of the treated chicks at 10 d of age was decreased (P < .005) compared with controls in each trial. The decreased number of Salmonella in the cecal contents of the 10-d-old treated chicks was correlated with elevated concentrations of propionic acid (P < .05) and total VFA (P < .1) in the cecal contents of the treated chicks 2 d after treatment. The results indicated that VFA-producing bacteria present in the mixed culture became rapidly established in the ceca of the treated chicks and effectively increased resistance to S. typhimurium challenge.