| Popis: |
A selective agar medium was developed for the isolation of Clostridium bifermentans. The formulation of the C. bifermentans selective agar (CBSA) was a modification of C. botulinum isolation agar (CBI) medium. The modifications included: a) change of the base medium to promote growth of C. bifermentans, b) increase of antimicrobial concentrations to improve selectivity and, c) lowering of the egg yolk concentration to lower the cost. The CBSA medium contains cycloserine (375 µg/ml), sulfamethoxazole (114 µg/ml) and, trimethoprim (6 µg /ml) as selective inhibitory agents. Quantitation of C. bifermentans strains on CBSA yielded counts comparable to those obtained on egg yolk agar control plates. The increased concentration of the selective agents in CBSA suppressed the growth of the lecithinase producing C perfringens, C. sordellii and other fecal organisms tested. Isolation of C. bifermentans from 20 seeded fecal specimens was readily achieved. The CBSA medium permits quantitative recovery of lecithinase positive colonies of C. bifermentans from human feces and can be used for large scale screening of various clinical specimens. |
