Quality analysis of commercial probiotic products for food animals.

Thirteen commercial probiotic feed products were examined for microbiological content and the results were compared with the information available on the product labels. Antibiotic resistance of Lactobacillus and Bacillus was investigated. All the products were inaccurately labelled in either numbers or species of bacteria. Misnaming at the species level was the most common flaw. Lactobacillus exhibited higher-antibiotic resistance than Bacillus did. Plasmid was found in both Lactobacillus (22%) and Bacillus (2.5%). The vanA gene was present in one L. plantarum and one B. subtilis isolate. The vanA-containing B. subtilis also harbored the tetW gene. None of the genes detected appeared to be associated with a conjugative plasmid.