Tóm tắt
Primary cultures of clinical material were screened for the presence of colonies suspected of being Streptococcus agalactiae (Lancefield group B). Sixty-three such cultures and 108 other isolates of beta-hemolytic streptococci (groups A, C, and G), encountered during the first 3 months of the investigation, were studied by Lancefield grouping, sodium hippurate hydrolysis, and a standardized CAMP test. All streptococci were inoculated perpendicularly to streaks of a beta-toxin-producing staphylococcus on sheep blood agar plates and incubated aerobically in a candle jar and anaerobically at 37 C. Plates were examined after 5 to 6 and 18 h of incubation. The production of a distinct "arrowhead" of hemolysis was indicative of a positive CAMP reaction. All group B streptococci produced a positive CAMP reaction in the candle jar or anaerobically, usually within 5 to 6 h, and aerobically after 18 h of incubation. All group A streptococci produced a positive reaction only under anaerobic conditions. Groups C and G streptococci were negative under all atmospheres. The CAMP reaction is a prompt and reliable procedure for the presumptive identification of group B streptococci when a candle jar atmosphere is used during incubation.
