THE ACTIVITY INVITRO OF TROSPECTOMYCIN SULFATE (U-63366F) AGAINST AMINOGLYCOSIDE-RESISTANT ENTEROCOCCI

Trospectomycin (U-63366F), a 6′-propyl analogue of spectinomycin, was tested against aminoglycoside-resistant enterococci. The MIC90 for Enterococcus faecalis was 4mg/l and that for E.faecium was 8mg/l. Trospectomycin alone was not bactericidal for enterococci, with MBC90 4096 mg/l for both E.faecalis and E.faecium. The addition of commercially available polyvalent immunoglobulin decreased significantly both the MICs and the MBCs and the rendered trospectomycin bactericidal for enterococci. Chequerboard titration of a combination of trospectomycin with ampicillin revealed an FIC index of 1.0 for all the isolates tested. Time-kill curves also did not show any enhancement of bactericidal activity of ampicillin when combined with trospectomycin. A combination of ampicillin and gentamicin was synergistic for enterococci under similar experimental conditions. Trospectomycin can be used as a safe alternative to aminoglycosides or β-lactam antibiotics in enterococcal infection where bactericidal activity is not required, or in the event of serious side effects from these two classes of antibiotics. © 1990 The British Society for Antimicrobial Chemotherapy.