In vitro antibacterial activities of eleven antibiotics against S. faecalis.

The in vitro antibacterial activities of penicillin, ampicillin, piperacillin, azlocillin, vancomycin, erythromycin, clindamycin, gentamicin, streptomycin, cefotaxime, and ceftriaxone against 198 S. faecalis strains were investigated, employing an agar dilution technique. Results were generally in accord with those of other studies. Ampicillin and penicillin showed equal activities. Twenty percent of the strains were resistant to erythromycin, which correlated with resistance to clindamycin. The activity of cefotaxime was fairly good, but the clinical importance of this observation warrants further investigation. Twenty percent showed high-level resistance to streptomycin. High-grade resistance to gentamicin was noted for one isolate only, making gentamicin the first-choice aminoglycoside for combination treatment at present.