Growth differences of Capnocytophaga canimorsus strains and some other fastidious organisms on various Columbia-based blood agar media.

Three human isolates of Capnocytophaga canimorsus from blood cultures showed no growth when cultivated on sheep blood agar plates based on BBL Columbia agar base, whereas the same three strains grew excellently on sheep blood agar plates based on Difco Columbia agar bases No. 2 or EH. Two of the three strains also grew well on blood agar plates based on bioMérieux Columbia agar. Strains that grew better on either Difco or bioMérieux Columbia based blood agar plates were found among Eikenella corrodens, Haemophilus aphrophilus, Kingella kingae, Lactobacillus sp., and Streptococcus adjacens, but these strains were never lost when cultivated on BBL Columbia agar plates. One strain of Lactobacillus failed to grow on Difco Columbia No. 2 agar and showed best growth on bioMérieux Columbia agar. Strains of Corynebacterium G 2, Corynebacterium afermentans and Streptococcus adjacens showed poor growth on chocolate agar when compared to blood agar media. Microbiologists should be aware of the importance of media formulations for optimal recovery of fastidious organisms.