Antistreptococcal activity of Sch 34343, a new penem antibiotic.

The in-vitro activity of Sch 34343 was compared with that of penicillin and cefotaxime against clinical isolates of streptococci. Sch 34343 was highly active against Streptococcus pneumoniae, viridans streptococci, streptococci of groups A, B, C and G, and Str. bovis. Ninety per cent of these strains were inhibited by less than or equal to 0.25, less than or equal to 0.12 and less than or equal to 0.06 mg/l of Sch 34343, penicillin and cefotaxime respectively. Activity of Sch 34343 against Str. faecalis was only moderate. Sch 34343 had very good bactericidal activity against group B streptococci, and showed high MBC/MIC ratios against penicillin-tolerant viridans streptococci and Str. faecalis. Sch 34343, 20 mg/l, and gentamicin, 4 mg/l, were synergistic against both of the penicillin-tolerant viridans streptococci, and one-third of the Str. faecalis strains.