Staphylococcus aureus is an important cause of peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Using standard broth microdilution and disk diffusion methodology, we evaluated the in vitro activity of selected antimicrobial agents against S. aureus strains isolated from CAPD patients to assess candidate regimens for 1) topical agent control of colonization, 2) oral chemotherapy of CAPD infectious complications, and 3) parenteral treatment of serious CAPD-associated staphylococcal infections. A total of 34 isolates (31 patients) of S. aureus were available for testing, including 29 isolates (29 patients) from pericatheter skin, four isolates (four patients) from the nares, and one isolate from an episode of peritonitis. Six of the isolates were oxacillin-resistant (ORSA). The antimicrobial agents tested by broth microdilution included 17 different quinolones, 10 cephalosporins, six glycopeptides, two aminoglycosides, and imipenem. A total of eight potential topical agents, including the antistaphylococcal agent mupirocin, were tested by disk diffusion. All of the quinolones, with the exception of nalidixic acid (MIC90 greater than 16 micrograms/ml), had excellent activity against both ORSA and oxacillin-susceptible S. aureus (OSSA) with the most active agent being WIN57273 (MIC90 less than or equal to 0.015 microgram/ml). Imipenem and the cephalosporins, with the exception of cefixime, ceftazidime, and E-1040, possessed good activity against OSSA. None of the beta-lactam agents tested were active against ORSA. Likewise, the aminoglycosides, amikacin and gentamicin, exhibited good activity against OSSA strains but no activity against ORSA strains. All glycopeptides tested demonstrated excellent activity against ORSA strains. Of the topical antimicrobial agents tested only bacitracin, mupirocin, and nitrofurantoin were active against all OSSA and ORSA strains tested.(ABSTRACT TRUNCATED AT 250 WORDS)