Abstract
Active infection control measures began being taken in geriatric wards starting in October 1991. MICs of 148 strains (nasal cavity 72, pharynx 44, and sputum 32) of Staphylococcus aureus were determined for 14 antimicrobial agents, isolated from Aino Memorial Hospital patients between August 1995 and August 1996. The frequency of methicillin-resistant S. aureus (MRSA) was 62.5% in the nasal cavity, 79.5% in the pharynx, and 93.7% in the sputum, suggesting that most strains of S. aureus remain resistant to β-lactam agents such as cephems, penicillins, and carbapenems. The frequency of strains susceptible to minocycline (MIC≤6.25μg/mL) was 61.1% in the nasal cavity, 54.5% in the pharynx, and 25.0% in the sputum. An increase in susceptible strains was brought by reinforcing infection control, including limiting the use of minocycline since 1987. No strains were highly intermediately or resistant to vancomycin. The frequency of strains with an MIC of 3.13μg/mL to vancomycin was 19.4% in the nasal cavity and 20.5% in the pharynx. No such strains were isolated from the sputum. Most strains (90.6%) in the sputum revealed an MIC of 1.56 μg/mL, suggesting the need to follow up MICs of S. aureus to vancomycin carefully in the future.
