Antibiotic susceptibilities of Afipia felis in axenic medium and in cells.

Afipia felis, one of the putative agents of cat scratch disease (CSD), is a facultative intracellular bacterium. Although CSD is considered not to be susceptible to antibiotic therapy, sporadic case reports indicated that aminoglycosides may be effective. We determined the in vitro antibiotic susceptibilities of three A. felis strains in axenic medium and in a cell model. In axenic medium, A. felis was susceptible to imipenem, aminoglycosides, and rifampin when using either the broth dilution technique or the agar technique. When grown in HeLa cells, A. felis was susceptible to amikacin and tobramycin but was resistant to the other compounds tested. Despite its intracellular location, A. felis can apparently be reached by aminoglycosides. Thus, the in vitro data presented here are in accord with the clinical data obtained in patients suffering CSD.