Antibiotic susceptibilities of bacteria isolated from ophthalmic specimens between 1984 and 2005 in Zurich, Switzerland.

BACKGROUND: Increasing resistance of bacteria cultured from ophthalmic specimens to antibiotic therapy has been documented worldwide. Inappropriate prescribing practices are thought to represent a major risk factor for antibiotic resistance. This study investigates the pattern of bacterial antibiotic susceptibility in Zurich, Switzerland over a period of twenty years. METHODS: Antibiotic susceptibilities of bacterial isolates from all ophthalmic specimens cultured at the Institute of Medical Microbiology in Zurich between 1984 and 2005 were analysed retrospectively. RESULTS: A total of 7,862 ocular surface samples have been collected. 3,010 specimens (38.3 %) were positive for aerobic bacteria. The strains isolated most frequently were Staphylococcus aureus (23.9 %), coagulase-negative staphylococci (16.1 %), Pseudomonas aeruginosa (10.0 %), Haemophilus influenzae (6.3 %), Escherichia coli (5.1 %), Serratia marcescens (4.7 %), and Streptococcus pneumoniae (3.9 %). Various bacteria accounted for the remaining 30.0 %. Susceptibility of these strains to the aminoglycosides, quinolones, and cephalosporins tested did not change over this period of time. CONCLUSION: The data suggest that bacteria cultured from ophthalmic specimens in Zurich, Switzerland have not changed their pattern of antibiotic susceptibility over the past 20 years.