Evaluation of novel vancomycin-containing medium for primary isolation of Kingella kingae from upper respiratory tract specimens.

A new selective medium (BAV), consisting of trypticase agar with 5% sheep hemoglobin and 2 micrograms of vancomycin per ml, was compared with the routine blood-agar medium for the primary isolation of Kingella kingae from upper respiratory specimens from a population of young children. Infection was detected by the BAV medium in 43 of 44 (98%) cultures positive for K. kingae, and detection of the organism was facilitated by inhibition of gram-positive flora. Infection was detected in only 10 of 44 (23%) positive cultures by the blood-agar medium, and plates were usually covered by abundant normal flora, making the recognition of K. kingae much more difficult. Challenge of the medium with different organisms of respiratory origin showed that the BAV medium was inhibitory for gram-positive cocci and Haemophilus influenzae but that it supported growth of eight K. kingae strains isolated from patients with invasive infections. The new medium appears to be a useful epidemiological tool for studying the respiratory carriage of K. kingae.