Antimicrobial Resistance Profiles of Bacterial Conjunctivitis Isolates from a Secondary Hospital in Shanghai: A 5-Year Retrospective Study (2020-2024).

PURPOSE: To analyze the pathogen distribution, epidemiological characteristics, and antimicrobial resistance patterns of bacterial conjunctivitis in a Shanghai secondary hospital from 2020 to 2024, providing evidence for clinical treatment optimization.

PATIENTS AND

METHODS

Conjunctival swab specimens from patients clinically diagnosed with bacterial conjunctivitis were collected between January 2020 and December 2024. Bacterial identification and antimicrobial susceptibility testing were performed using the VITEK 2 Compact system and Kirby-Bauer disk diffusion method, respectively. Statistical analyses were conducted using WHONET 5.6 and SPSS 26.0.

RESULTS

Among the 611 specimens, 58 bacterial isolates were identified (9.5% positivity rate). Gram-positive cocci predominated (70.7%, 41/58), primarily Staphylococcus epidermidis (21 strains) and Staphylococcus aureus (10 strains). Gram-negative bacilli accounted for 15.5% (9/58), including Pseudomonas aeruginosa and multidrug-resistant Acinetobacter baumannii. A significant seasonal variation was observed, with higher incidence in summer-autumn (72.4%) than in winter (12.1%, P=0.005). Cases in 2023-2024 nearly doubled those in 2020-2022 (65.5% vs 34.5%). The detection rate of S. aureus increased significantly annually (P=0.043). High resistance rates were observed among Gram-positive cocci to penicillin (89.5%), oxacillin (60.5%), and erythromycin (55.3%). All Gram-positive isolates remained susceptible to vancomycin, linezolid, and tigecycline. Gram-negative isolates exhibited 100% resistance to ampicillin, with A. baumannii demonstrating pandrug-resistance.

CONCLUSION

Gram-positive cocci, particularly Staphylococcus spp. were the predominant pathogens in bacterial conjunctivitis, with an increasing trend of S. aureus and multidrug-resistant A. baumannii. The significant seasonal pattern and high resistance to first-line antibiotics emphasize the necessity for culture-guided therapy and enhanced antimicrobial stewardship in ocular infections.