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

Abstract

To investigate the conjunctival and nasal flora and the antibiotic susceptibility profiles of isolates from patients undergoing cataract surgery. Observational and cross-sectional study. A single-centre study in Taiwan. 128 consecutive patients precataract surgery. Conjunctival 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. The positive culture rate from conjunctiva was 26.6%, yielding 84 isolates. Coagulase-negative <i>Staphylococci</i> were 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 for <i>S<i>taphylococcus</i> aureus</i> was 21.9%, and six isolates were methicillin-resistant. No subjects had <i>S. aureus</i> colonisation on conjunctiva and nares simultaneously. There were no associated risk factors for colonisation of methicillin-resistant <i>Staphylococci.</i> CONCLUSION: The most common conjunctival bacterial isolate of patients undergoing cataract surgery was coagulase-negative <i>Staphylococci</i> in Taiwan. Because of predominant antibiotic preferences and selective antibiotic pressures, <i>Staphylococci</i> were more susceptible to fluoroquinolones but less to tobramycin than in other reports. Additionally, methicillin-resistant <i>Staphylococci</i> exhibited co-resistance to tobramycin but not to fluoroquinolones.