Sch 29482, laboratory evaluation of a new penem antibiotic.

Abstract

The antibacterial activity of a new penem antibiotic, Sch 29482 (SCH), was examined in comparison with appropriate cephalosporins and penicillins. The drug inhibited penicillinase-positive and negative staphylococci equally well, being 2–5 times more active than cephalothin or cefamandole and 10–20 times more active than methicillin. Staphylococci resistant to methicillin were susceptible to SCH in agar dilution tests. Staphylococci tolerant to methicillin were also tolerant to SCH. Streptococci and pneumococci were highly susceptible to the drug. The agent was of only moderate activity against enterococci, especially Streptococcus faecium strains. MICs of ampicillin and penicillin G against enterococci were 4–8 times lower than those of SCH. SCH was bactericidal. Neither the choice of the method used for susceptibility testing, nor the size of the inoculum nor various test media influenced the in-vitro activity of this drug against a representative collection of Gram-negative and Gram-positive bacteria.