Antibiotic Susceptibilities of Bacteria Isolated from Ophthalmic Specimens between 1984 and 2005 in Zurich, Switzerland

Abstract

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. 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. 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. 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.