[Antibacterial activities of fosfomycin against recent clinical isolates from patients of otitis media and otitis externa].

Clinical isolates from patients with otitis media and/or otitis externa were collected at otorhinology clinics nationwide and sent to us during 1989, 1991 and 1993. Minimum inhibitory concentrations (MICs) of fosfomycin (FOM) and of reference drugs against these strains were determined to investigate year-to-year antibacterial activity of FOM. A comparative analysis of the results revealed trends described below. 1. The MIC90 of FOM against Staphylococcus aureus subsp. aureus increased 4 times by 1993 as compared to those measured for strains isolated in 1984 and 1985, when FOM for otic use was under development. This was thought to be due to the recent increase in the detection frequency of methicillin-resistant S. aureus (MRSA) which is also resistant to FOM. 2. No annual changes were seen for MIC distribution of FOM against Proteus group and Pseudomonas aeruginosa. 3. Since there was no large annual change in the antibacterial activity of FOM against recent clinical isolates obtained from patients with otitis media and/or otitis externa, FOM may be considered as one of the useful drugs even now, in the mid-1990's.