Investigations on ofloxacin: antibacterial activity and influence on the immune system.

The in vitro activity of ofloxacin was tested against freshly isolated strains, from clinical material, of Pseudomonas aeruginosa, Staphylococcus aureus, and coagulase-negative staphylococci, including strains that were resistant to methicillin and/or novobiocin. 97% of the Pseudomonas strains were inhibited by ofloxacin concentrations in the range of 0.78 to 6.25 mg/l, with 55% of the strains being inhibited by concentrations up to 1.56 mg/l. All of the staphylococci strains, including those resistant to novobiocin and/or methicillin, were sensitive to ofloxacin in the range 0.19 to 1.56 mg/l. The influence of ofloxacin on cellular and humoral host immunity was evaluated both in vivo and in vitro. The influence of the compound on phagocytic activity of human polymorphonuclear leucocytes was evaluated by luminol-enhanced chemiluminescence. Ofloxacin did not influence cell-mediated immunity. It had no effect on chemotaxis. The use of sub-inhibitory concentrations of ofloxacin enhanced the phagocytic kill rate.