[Antimicrobial activities of sultamicillin against clinical isolates obtained from outpatients]

Minimum inhibitory concentrations (MICs) were determined for sultamicillin (SBTPC), and for other major oral beta-lactam agents against clinically isolated strains collected from outpatients during a period from August, 1992 to February, 1993, and the following conclusions were obtained. 1. The ratio of penicillinase (PCase)-producing strains of Staphylococcus aureus was 96.0% and that of methicillin-resistant S. aureus (MRSA) was 12.0%. MIC90 of SBTPC against S. aureus including MRSA was 6.25 micrograms/ml. No increasing tendency was observed for S. aureus resistant to SBTPC. 2. No resistant strains were found among Streptococcus pyogenes and Enterococcus faecalis against penicillins (PCs) including SBTPC. But PCs and cephems (CEPs) insensitive or resistant Streptococcus pneumoniae were observed in 22.0% among all the strains of S. pneumoniae. 3. 100% of the tested both strains of Escherichia coli and Proteus mirabilis were beta-lactamase producers. 12.0% of the tested strains of Haemophilus influenzae and 16.0% of the strains of Neisseria gonorrhoeae were also beta-lactamase producers. SBTPC showed strong antimicrobial activity against most of these beta-lactamase producing strains. However, in our study of beta-lactamase productivity using plural substrates and test methods, it appeared that a part of strains of E. coli might produce beta-lactamase of "Extended broad-spectrum". MICs of SBTPC and CEPs against those strains were distributed rather in a high range. 4. The results of the study suggested that the resistant strains of S. pneumoniae against PCs and CEPs might be increasing year by year. Some of strains of E. coli, resistance against the 2 agents were observed. It is important to keep observing changes in resistance of such organisms in the future. 5. The antimicrobial activities of SBTPC against clinically isolated strains in this study indicated potential problems such as those mentioned above. It is, however, also confirmed that SBTPC shows still strong antimicrobial activities against most of beta-lactamase producing strains found in daily medical examinations. Taking into consideration of the strong activities of SBTPC against so-called indirect pathogenicity caused by beta-lactamase producing indigenous bacteria reported lately, SBTPC may be a useful antibiotic for community acquired infections in the 1990's.