[Antimicrobial activities of sulbactam/ampicillin against clinically isolated microbial strains]

Antimicrobial activities were examined for sulbactam/ampicillin (SBT/ABPC) against clinically isolated microbial strains in 1987, 1990, 1994. Besides, the beta-lactamase productivity and MICs of these strains were measured, and the following conclusions were obtained. 1. The ratio of beta-lactamase producing strains were 90% of methicillin (DMPPC)-susceptible Staphylococcus aureus subsp. aureus (MSSA), about 80% of DMPPC-resistant S. aureus (MRSA), 100% of Escherichia coli, Klebsiella pneumoniae subsp. pneumoniae and Proteus mirabilis, 95% of Moraxella subgenus Branhamella catarrhalis and 15-20% of Haemophilus influenzae. Several kinds of beta-lactamase productivity were observed. 2. Antimicrobial activities of SBT/ABPC against beta-lactamase producing strains of MSSA, M. (B.) catarrhalis, H. influenzae, and almost all of Enterobacteriaceae were stronger than those of ampicillin (ABPC) and piperacillin (PIPC), but antimicrobial activities of SBT/ABPC were weak against MRSA and cephems (CEPs)-resistant strains detected in some of Enterobacteriaceae. 3. It appeared that benzylpenicillin (PCG)-insensitive Streptococcus pneumoniae (PISP) or PCG-resistant S. pneumoniae (PRSP) and CEPs-resistant Escherichia coli increased year by year. 4. Antimicrobial activities of SBT/ABPC were strong against Streptococcus pyogenes, S. pneumoniae, M. (B.) catarrhalis and H. influenzae including beta-lactamase producing strains. Additionally, beta-lactamase inhibiting effect of SBT was observed against beta-lactamase produced by S. aureus and K. pneumoniae which demonstrate indirect pathogenicity. Thus, SBT/ABPC is an injectable antibiotic that is expected to demonstrate clinical usefulness, especially as the first line drug for the respiratory tract infections that are community-acquired.