Effect of ofloxacin combined with Lactobacillus casei against Mycobacterium fortuitum infection induced in mice.

Multiple injections of ofloxacin (subcutaneous or oral) in combination with a Lactobacillus casei preparation, LC9018 (subcutaneous), in mice infected intravenously with Mycobacterium fortuitum led to a marked delay in the incidence of spinning disease, a lowered incidence of gross renal lesions, and an increase in the rate of elimination of organisms from the kidneys. This indicates synergism in the therapeutic efficacy of the two agents. When the antimicrobial ability of peritoneal macrophages (M phi s) against M. fortuitum was measured in medium with or without ofloxacin, growth of the organisms was more markedly inhibited by ofloxacin in LC9018-induced M phi s than in normal M phi s. Synergism in the therapeutic activity of oxfloxacin plus LC9018 is assumed to be mediated in part by host M phi s, that is, functional stimulation of host M phi s by LC9018 treatment results in the synergistic effects of the two agents.