[Typing of Bacteroides fragilis by bacteriocin production]

Sixty-four strains of Bacteroides fragilis isolated from clinical specimens were tested for their bacteriocin production. It showed that 65.6% of them produced bacteriocin(s) and gave different patterns of inhibition. Among them 9 with clear inhibition zones were chosen as the indicator strains. With this indicator s,et 75.2% of 109 clinically isolated B. fragilis strains could be typed, with type 482 as the predominant type. The colonial dissociants gave the same bacteriocin type, but small and opaque colonies tend to lose their bactericidal ability.