Cephalexin-supplemented Jones-Kendrick charcoal agar for selective isolation of Bordetella pertussis: comparison with previously described media

Publisher Website
Google Scholar
Abstract
Unsupplemented Jones-Kendrick (JK) charcoal agar, JK agar supplemented with 0.5 U of penicillin/ml, JK medium supplemented with 2.5 .mu.g of methicillin/ml and JK medium supplemented with 40 .mu.g of cephalexin/ml were evaluated to determine their ability to support growth of B. 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. Penicillin- and cephalexin-supplemented media were more inhibitory for early growth of B. pertussis than was medium supplemented with methicillin. After 5 days of incubation at 35.degree. C, all media supported good growth of this organism. When employed to detect B. pertussis in sham specimens, prepared by mixing normal pharyngeal material with each of the 5 B. pertussis stock cultures, the medium containing cephalexin was judged superior to all other media tested in its combined ability to suppress the growth of normal pharyngeal flora and to allow early detection of Bordetella colonies. All media tested retained their efficacy after 9 wk of storage at 2-8.degree. C.