Four agar media, Jones-Kendrick (JK) charcoal agar unsupplemented, JK agar supplemented with 0.5 U of penicillin per ml, JK medium supplemented with 2.5 ,ug of methicillin per ml, and JK medium supplemented with 40 ,ug of cephalexin per ml, were evaluated to determine their ability to support growth of Bordetella pertussis, their ability to selectively inhibit normal pharyngeal flora while maintaining growth of B. pertussis, and their stability during storage. Five stock cultures of B. pertussis were plated on each of the media. Penicillinand