Selectivity of Mitis Salivarius agar and a new selective medium for oral streptococci in dogs

An evaluation on the applicability of Mitis Salivarius agar (MS) medium, commonly used for the detection of oral streptococci in human and animals, to dog specimens and the development of a new selective medium for isolating streptococci from the canine oral cavity are described. Oral samples from dogs were cultured on MS medium under anaerobic conditions. The predominant facultative anaerobic bacteria on MS plates were gram-negative rods. Selectivity of streptococci on MS medium was 21.2%. A new selective medium, designated MS-CAN-AE, was developed for the isolation of streptococci from the canine oral cavity. The average growth recovery of laboratory and clinically isolated strains of streptococci on MS-CAN-AE medium was 84.1% of that on MS medium. Gram-positive rods and gram-negative rods and cocci rarely grew on the MS-CAN-AE. The selectivity of MS-CAN-AE was 95.0% for clinical samples. MS-CAN-AE medium will be helpful for investigations of streptococci in the canine oral cavity.