In vitro antibacterial activity of trospectomycin (U-63366F), a novel spectinomycin analog

Trospectomycin (U-63366F) is a novel spectinomycin analog with broad-spectrum antibacterial activity. The in vitro activity of this analog was compared with that of spectinomycin and other reference antibiotics against 411 clinical isolates of aerobic and anaerobic bacteria. MICs were determined by agar or broth dilution methods. The stability of trospectomycin in the presence of an enzyme extract derived from spectinomycin-resistant Escherichia coli was determined. Trospectomycin was more active than spectinomycin (4- to 32-fold) against strains of numerous bacterial species, including staphylococci, streptococci, Haemophilus influenzae, Branhamella catarrhalis, Neisseria gonorrhoeae, Proteus species, Bacteroides species, Clostridium difficile, Clostridium species, and Chlamydia trachomatis. Trospectomycin demonstrated a moderate level of activity (comparable to that of spectinomycin) for most species of the family Enterobacteriaceae tested and was generally cross resistant with spectinomycin. Trospectomycin was susceptible to inactivation by crude enzyme preparations from spectinomycin-inactivating strains of E. coli. Trospectomycin inhibited a variety of clinically important organisms, including agents of sexually transmitted diseases and pelvic inflammatory disease. Clinical studies with this novel aminocyclitol antibiotic are in progress.