ANTIBIOTIC SUSCEPTIBILITY OF STAPHYLOCOCCAL ISOLATES FROM PATIENTS WITH VASCULAR CATHETER-RELATED BACTEREMIA - POTENTIAL ROLE OF THE COMBINATION OF MINOCYCLINE AND RIFAMPIN

The antimicrobial susceptibility to ten antibiotics of 197 staphylococ cal isolates recovered over a 10-year period from patients with vascul ar catheter-related bacteremia was examined. Isolated organisms includ ed methicillin-sensitive Staphylococcus aureus (95 isolates), methicil lin-resistant S. aureus (42 isolates) and methicillin-resistant S. epi dermidis (60 isolates). A microtiter assay was used to determine the M IC and MBC of individual antibiotics and to conduct time-kill studies of certain drug combinations. The activity of clidamycin, cefamandole and oxacillin was generally restricted to methicillin-sensitive organi sms, whereas daptomycin, novobiocin, teicoplanin and vancomycin exhibi ted bactericidal activity against all tested staphylococcal species. B acterial resistance to ciprofloxacin was detected among the more recen t isolates of methicillin-resistant staphylococci. Minocycline and rif ampin demonstrated bacteriostatic and bactericidal activity, respectiv ely, against all groups of organisms. The interaction of rifampin with minocycline, vancomycin, or novobiocin was generally indifferent. The results of this study support the ongoing efforts for evaluation of t he antimicrobial efficacy of vascular catheters coated with the combin ation of minocycline and rifampin.