ENTEROCOCCUS-FAECIUM - IN-VITRO ACTIVITY OF ANTIMICROBIAL DRUGS, SINGLY AND COMBINED, WITH AND WITHOUT DEFIBRINATED HUMAN BLOOD, AGAINST MULTIPLE-ANTIBIOTIC-RESISTANT STRAINS

The minimal inhibitory (MICs) and bactericidal concentrations of 14 an timicrobial drugs were determined against 17 clinical isolates of Ente rococcus faecium, including 4 glycopeptide-resistant strains. Both tei coplanin and vancomycin lacked bactericidal activity against all 13 su sceptible isolates. Time-kill experiments served to test various antib iotic combinations chiefly against glycopeptide-resistant strains in M ueller-Hinton broth (MHB) and in MHB supplemented with 65% (v/v) fresh defibrinated human blood. Co-trimoxazole, fusidic acid, and novobioci n yielded bacteriostatic effects. Rifampin was bactericidally active a gainst rifampin-susceptible strains (MICs = 0.125 mug/ml), but less so against low-level-rifampin-resistant (MICs = 2-8 mug/ml) strains in M HB. However, in the presence of human blood, rifampin (2 mug/ml) combi ned with co-trimoxazole (0.25/4.75 mug/ml) killed rifampin-susceptible and low-level-rifampin-resistant, but not moderate-level-rifampin-res istant (MICs = 16-32 mug/ml) strains of E. faecium. Of two topical dru gs examined, mupirocin merely inhibited strains of E. faecium; convers ely, taurolidine at 2,000 mug/ml was efficacious against all strains e xamined, although the kinetics of bactericidal activity were retarded somewhat in the presence of 65 vol% human blood.