Prevention of bacteremia caused by alpha-hemolytic streptococci by roxithromycin (RU-28 965) in granulocytopenic patients receiving ciprofloxacin.

We previously demonstrated that ciprofloxacin prevents infections caused by gram-negative bacilli in patients with granulocytopenia. However, in patients with intensive cytotoxic treatment leading to severe mucosal damage a high incidence of bacteremias caused by alpha-hemolytic streptococci was seen. In the present study 45 consecutive patients undergoing intensive cytotoxic treatment received a short course of roxithromycin (10 days) in addition to ciprofloxacin for prevention of bacteremias caused by alpha-hemolytic streptococci. The results of this study were compared with the results obtained in previous comparable patients receiving ciprofloxacin alone. During the days with addition of roxithromycin no infections caused by alpha-hemolytic streptococci occurred, while in the control group of 80 patients 16 bacteremias (20%) were seen. Although roxithromycin was shown to antagonize bactericidal action of ciprofloxacin on gram-negative bacilli in vitro, in vivo study based on serum bactericidal titers and on results of surveillance cultures showed no antagonistic interactions.