C-19393 S2 and H2, new carbapenem antibiotics. I. Taxonomy of the producing strain, fermentation and antibacterial properties

C-19393 S2 and H2 are new carbapenem antibiotics produced by a streptomycete. The producing strain was taxonomically studied and named Streptomyces griseus subsp. cryophilus. Cobaltous compounds were necessary for production of the antibiotics. C-19393 S2 and H2 showed a broad spectrum of antibacterial activities with C-19393 H2 being 8 approximately 120 times more active than C-19393 S2. They also exhibited beta-lactamase-inhibiting activities and acted synergistically with ampicillin and cefotiam against clinical isolates resistant to beta-lactam antibiotics.