DOI: 10.33808/clinexphealthsci.1975761 ISSN: 2459-1459

Distribution of Ocular Pathogens and Antimicrobial Resistance Patterns in a Tertiary Care Center: A Retrospective Analysis from 2023 to 2026

Barış Can, Işıl Akdemir, Furkan Çam, Gamze Özkan Çat, Arzu Akşit İlki
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Objective: Ocular infections are important causes of ocular morbidity and may result in permanent visual impairment if not diagnosed and treated promptly. Knowledge of local pathogen distribution and antimicrobial resistance patterns is essential for guiding empirical therapy. This study aimed to evaluate the distribution of bacterial pathogens isolated from ocular specimens and their antimicrobial resistance profiles in a tertiary care center.Methods: This retrospective study included ocular specimens submitted to the microbiology laboratory of a tertiary care center between January 2023 and May 2026. Conjunctival swabs, ocular fluid samples (vitreous, aqueous, and anterior chamber fluids), contact lenses, and corneal tissue specimens were evaluated. Bacterial identification and antimicrobial susceptibility testing results obtained during routine laboratory practice were reviewed. Antimicrobial susceptibility results were interpreted according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. Isolates categorized as “susceptible, increased exposure (I)” were considered susceptible.Results: A total of 1,347 ocular specimens were analyzed, of which 156 (11.6%) yielded bacterial growth, resulting in 184 bacterial isolates. Polymicrobial growth was observed in 24 (15.4%) culture-positive specimens. Conjunctival swabs accounted for the majority of bacterial isolates (63.6%), followed by ocular fluid samples (30.4%). Coagulase-negative staphylococci (CoNS) were the most frequently isolated microorganisms (28.8%), followed by Staphylococcus aureus (11.4%), Enterobacterales (11.4%), Pseudomonas aeruginosa (9.2%), and Haemophilus influenzae (7.6%). Methicillin resistance rates, determined by cefoxitin susceptibility testing, were 56.6% among CoNS isolates and 33.3% among S. aureus isolates. Among Gram-negative bacteria, resistance rates in P. aeruginosa ranged from 11.8% to 20.0% for commonly tested antimicrobials, whereas Enterobacterales demonstrated the highest resistance to ceftazidime (22.2%) and ceftriaxone (21.1%). No resistance to linezolid or vancomycin was detected among Gram-positive isolates.Conclusion: CoNS, S. aureus, and Gram-negative bacteria, particularly Enterobacterales and P. aeruginosa, were the predominant pathogens in ocular infections. High methicillin resistance rates among staphylococci emphasize the importance of local surveillance data for empirical treatment decisions. Continuous monitoring of antimicrobial resistance patterns may contribute to optimizing antimicrobial stewardship and improving patient outcomes in ocular infections.

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