Abstract: Objective To investigate the distribution of conjunctival bacteria before different type of  keratoplasty (include limbal stem cell transplantation) and the factors that affecting the positive rate as well as the antibiotic susceptibility. Design Retrospective case series. Participants 572 patients underwent keratoplasty in Peking University 3rd Hospital were included and patients with current infection were excluded. Method Bacterial culture of conjunctival sac, results of antibiotic susceptibility and clinic data were reviewed. Clinic data of acute infection after surgery was also collected. All cases were divided into case group (positive culture) and control group (negative culture) depending on the result of conjunctival culture. Main Outcome Measures Clinical information, conjunctival culture results and antibiotic susceptibilities. Results The positive rate of bacterial culture was 4% (23/572). The main detected bacteria were Staphylococcus epidermidis (78.2%). There was no significant difference in gender, age, left/right eyes, type of keratoplasty, history of eye surgery, diabetes mellitus (all P>0.05). The positive rate of local antibiotic time (1 day, 2 days, 3 days and more) before keratoplasty was statistically significant (χ2=5.807, P=0.046). The positive rate was significantly different in different protopathy（P=0.001）and immune diseases was the highest (38.5%). Antibiotic susceptibility test suggest that gram positive bacteria was sensitive to rifampicin (100%) and vancomycin (88.9%). One patient with Stevens-Johnson syndrome had acute infection after keratoplasty, and his result of conjunctival culture was Escherichia coli. Conclusion The positive rate of conjunctival bacteria culture before keratoplasty would reduce by extend time of antibiotic. The patients with immune diseases should be concerned due to the high positive rate of bacteria culture. The positive result of preoperative conjunctival bacteria culture might have relation with acute infection after surgery. (Ophthalmol CHN, 2021, 30: 131-135)

Key words:  keratoplasty, conjunctiva, bacteria, antibiotic susceptibility test