Antibiotic susceptibility profiles of ocular and nasal flora in patients undergoing cataract surgery in Taiwan: an observational and cross-sectional study

Abstract

ObjectiveTo investigate the conjunctival and nasal flora and the antibiotic susceptibility profiles of isolates from patients undergoing cataract surgery.DesignObservational and cross-sectional study.SettingA single-centre study in Taiwan.Participants128 consecutive patients precataract surgery.Primary and secondary outcome measures methodsConjunctival and nasal cultures were prospectively obtained from 128 patients on the day of cataract surgery before instillation of ophthalmic solutions in our hospital. Isolates and antibiotic susceptibility profiles were identified through standard microbiological techniques. Participants were asked to complete a questionnaire on healthcare-associated factors.ResultsThe positive culture rate from conjunctiva was 26.6%, yielding 84 isolates. Coagulase-negativeStaphylococciwere the most commonly isolated organisms (45.2%), and 35% of staphylococcal isolates were methicillin-resistant. Among staphylococcal isolates, all were susceptible to vancomycin, and 75%–82.5% were susceptible to fluoroquinolones. Methicillin-resistant isolates were significantly less susceptible than their methicillin-sensitive counterparts to tobramycin, the most commonly used prophylactic antibiotic in our hospital (28.6% vs 69.2%; p=0.005). The positive culture rate from nares forStaphylococcusaureuswas 21.9%, and six isolates were methicillin-resistant. No subjects hadS. aureuscolonisation on conjunctiva and nares simultaneously. There were no associated risk factors for colonisation of methicillin-resistantStaphylococci.ConclusionThe most common conjunctival bacterial isolate of patients undergoing cataract surgery was coagulase-negativeStaphylococciin Taiwan. Because of predominant antibiotic preferences and selective antibiotic pressures,Staphylococciwere more susceptible to fluoroquinolones but less to tobramycin than in other reports. Additionally, methicillin-resistantStaphylococciexhibited co-resistance to tobramycin but not to fluoroquinolones.