Intraphagocytic bactericidal activity of ofloxacin compared with that of aztreonam and ceftriaxone against Serratia marcescens.
Addition of phenylbutazone (2 mg/ml) to 55 vol % of fresh defibrinated human blood permitted leukocytic ingestion of serum-resistant Serratia marcescens bacteria, but blocked phagocytic killing activity. The group A (phage tail) bacteriocin bA+ 16 served to kill extraphagocytic test bacteria. At greater than or equal to 2 X MBC, the DNA gyrase inhibitor ofloxacin revealed potent intraphagocytic bactericidal activity against S. marcescens test bacteria (99% kill; 3 h observation period) which corresponded to that of the control drug rifampin (97% kill). The monobactam aztreonam (11% kill) and the third generation cephalosporin ceftriaxone (14% kill) corresponded to cefotaxime (26% kill) in terms of suboptimal intraphagocytic activity. Ofloxacin and aztreonam yielded additive effects following combination of supra-(2 X MIC) and inhibitory (MIC), but not sub-inhibitory (0.5 X MIC) concentrations with 55 vol % of defibrinated human blood against S. marcescens and Escherichia coli control strain ATCC 25922; sub- and inhibitory concentrations of ceftriaxone yielded indifferent effects.
D001398:Aztreonam / Q000494:pharmacology*; D002443:Ceftriaxone / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects; D006801:Humans; D015242:Ofloxacin; D010078:Oxazines / Q000494:pharmacology*; D010586:Phagocytes / Q000382:microbiology*; D010587:Phagocytosis; D012293:Rifampin / Q000494:pharmacology; D012706:Serratia marcescens / Q000187:drug effects*
D010078:Oxazines; D002443:Ceftriaxone; D015242:Ofloxacin; D001398:Aztreonam; D012293:Rifampin