A comparison of the in-vitro activity of seventeen antibiotics against Streptococcus faecalis

The in-vitro activity of seventeen antibiotics against 177 clinical strains of Streptococcus faecalis was evaluated. Ampicillin and mezlocillin were the most active beta-lactams tested (geometric mean MICs, 0.61 and 0.74 mg/l, respectively). Aminoglycosides showed poor activity and 22.6% of the strains were resistant to 2000 mg/l of streptomycin. No correlation was observed between MICs of gentamicin and streptomycin. Moderate activity was observed when testing norfloxacin and ciprofloxacin. Teicoplanin and co-trimoxazole were extremely active, showing geometric mean MICs of 0.59 and 0.08 mg/l respectively. All strains were susceptible to vancomycin and teicoplanin.