Conjunctival colonisation and antibiotic resistance of coagulase-negative Staphylococcus after cataract surgery: a 6-month longitudinal study at a medical centre in Taiwan

OBJECTIVE: To explored 6-month longitudinal changes in conjunctival colonisation and antibiotic resistance profiles of coagulase-negative Staphylococcus (CNS) after cataract surgery with 1 month tobramycin treatment. DESIGN: Prospective cohort study between 1 August 2012, and 31 July 2013. SETTING: A single medical centre in Taiwan. PARTICIPANTS: A total of 128 Taiwanese patients with 46.9% of male participants. INTERVENTIONS: Samples from the conjunctival sacs of both operation (OP) and non-OP eyes were obtained separately before cataract surgery and at 1, 3 and 6 months after surgery. Tobramycin (0.3%) treatment was applied four times daily for 1 month postoperatively. MAIN OUTCOME MEASURE: Identification of CNS isolates and their antibiotic susceptibility by using disk diffusion or E-test. RESULTS: CNS was detected in 24.2% of patients at baseline. During postoperative follow-up, the CNS colonisation rate did not decrease in either eye but showed an increasing trend in the OP eyes at 1 month (p=0.06). The colonisation rate showed no significant difference between the OP and non-OP eyes from baseline to a specific follow-up. We observed a significant increase (p<0.05) in resistance to tobramycin at 1 month and to ciprofloxacin at 3 months in the OP eyes and to trimethoprim/sulfamethoxazole at 1 month and 3 months and to oxacillin at 6 months in the non-OP eyes. CONCLUSIONS: During the 6-month postoperative follow-up, 0.3% tobramycin administration failed to reduce CNS colonisation but increased resistance to several antibiotics. Postoperative antibiotic treatment may be replaced by other evidence-endorsed prophylactic routines.