Bactericidal activity of antimicrobial agents for treponemes.

Bactericidal studies of antibiotics on treponemes have been limited to a small group of organisms and to a limited number of antimicrobial agents. Eagle and Musselman (1944) determined the sensitivity in vitro of the non-virulent Reiter treponeme to penicillin G. Penicillin concentrations of between 01 and 0-25 units/ml. medium killed 90 to 99 per cent. of the spirochaetes in 8 to 12 hrs. Penicillin was equally active against a cultivable mouth treponeme and the Nichols, Noguchi, and Kazan treponemes. Eagle, Musselman, and Fleischman (1948) tested the Reiter treponeme for bactericidal sensitivity to bacitracin. They reported that 0-025 units bacitracin/ ml. medium were treponemicidal within 24 to 48 hrs. Fitzgerald and Hampp (1952) investigated the treponemicidal activity of several antibiotics against three strains of Treponema vincentii and three strains of an oral treponeme. Subculture into antibiotic-free medium was used to distinguish inhibitory from bactericidal concentrations. Treponemicidal concentrations for penicillin, aureomycin, chloramphenicol, and streptomycin at 7 days were two to four times those of the inhibitory concentration. Hampp and Fitzgerald (1959) examined three strains of T. vincentii, three oral treponemes, and three strains of Borrelia buccalis. Absence of motility and the presence of bizarre forms were considered to be evidence ofspirochaetal death. Antibiotics considered to be treponemicidal were penicillin, oleandomycin, novobiocin, erythromycin, and vancomycin. The purpose of this study was to determine the bactericidal concentrations of a large number of antimicrobial agents using representative strains of the cultivable species or groups of treponemes. In addition, investigations were made into the occurrance of spontaneous and penicillin-induced mutants.