Influence of antimicrobial subinhibitory concentrations on hemolytic activity and bacteriocin-like substances in oral Fusobacterium nucleatum

Fusobacterium nucleatum is considered for its role in colonization of initi al and late microorganisms in dental plaque and for its coaggregation with other bacterial species. It is known that action of different antimicrobial substances may interfere with either virulence factors or with host-bacter ia interaction. The goal of this study was to examine the influence of subi nhibitory concentrations of chlorhexidine, triclosan, penicillin G and metr onidazole on hemolytic activity and bacteriocin-like substance production o f oral F. nucleatum. A high resistance to penicillin G was observed and 63% of the isolates were beta-lactamase positive. All the tested isolates were susceptible to metronidazole. F. nucleatum isolates grown with or without antimicrobials were alpha-hemolytics. Bacteriocin-like substance production was increased in isolates grown with penicillin G. Impaired production of hemolytic or antagonic substances can suggest a role in the regulation of o ral microbiota.