In vitro efficacy of several antibiotics against intracellular S. aureus in chronic granulomatous disease.

We report the case of a one-year-old boy with chronic granulomatous disease (CGD), characterized by a defect in the polymorphonuclear leukocytes (PMN) which ingest, but do not kill catalase-positive bacteria such as S. aureus. This well-known observation led us to study the ability of clindamycin, rifampin, co-trimoxazole (TMP-SMX), methicillin and gentamicin to kill intracellular S. aureus in CGD and in normal PMN. Clindamycin killed S. aureus more effectively when these bacteria were intracellular than in the absence of PMN; rifampin was equally active on the same microorganisms in presence and absence of PMN, whereas TMP-SMX, methicillin and gentamicin were less effective in killing intracellular S. aureus. Similar results were obtained in CGD and in normal PMN. These results suggest that clindamycin and rifampin would be a reasonable choice in the treatment of staphylococcal infections in patients with CGD.