Etiological characteristics of 3,691 cases of microbial keratitis: an 8-year longitudinal study

The etiological spectrum of microbial keratitis exhibits significant regional variability. However, existing domestic and international resistance monitoring systems do not adequately address the specific needs of clinical practice. We analyzed a cohort of 3,691 patients diagnosed with microbial keratitis in the southern region of Zhejiang Province, China between 2016 and 2023. The patients' ages ranged from 2 to 93 years (979 men and 403 women). The microbial culture positivity rate is relatively low (38.72%). Trauma and foreign body entry emerged as significant risk factors. Mixed infections accounting for 4.85% posed challenges for diagnosis and treatment. Filamentous fungi, predominantly <i>Fusarium</i> spp., dominated the microbial landscape. Prominent bacterial pathogens included <i>Pseudomonas aeruginosa</i>, <i>Streptococcus pneumoniae</i>, <i>Staphylococcus epidermidis</i>, and <i>Staphylococcus aureus. Acanthamoeba spinosa</i> was an important pathogen affecting the cornea in this region. The observed resistance patterns emphasized the urgency for alternative therapeutic strategies targeting resistant gram-positive (e.g., erythromycin, penicillin, oxacillin) and -negative (e.g., trimethoprim-sulfamethoxazole, tetracycline) bacteria as well as refractory fungi, such as <i>Candida albicans</i> (voriconazole-resistant) and <i>Aspergillus flavus</i> (resistant to itraconazole and amphotericin B). Resistance to ceftazidime, meropenem, and erythromycin exhibited a slight upward trend, diverging from the overall bacterial resistance trend observed in China. High isolation rates of methicillin-resistant <i>S. aureus</i> and macrolide-resistant <i>S. pneumoniae</i> underscored the need for enhanced infection control measures and targeted interventions against these resistant pathogens. This study elucidated the evolving patterns of antibiotic resistance among ocular isolates in the region, providing a critical foundation for the effective application of antimicrobial therapies in clinical practice.IMPORTANCECurrently, our region does not possess extensive monitoring data regarding antibiotic resistance trends in ocular isolates, especially those derived from corneal infections. This study addresses a critical component of ophthalmic microbiology by analyzing long-term data to identify trends in etiological agents and their clinical implications. It aimed to fill the void in epidemiological data on ocular isolates within our region, providing scientific insights essential for the comprehensive monitoring of ocular microbial drug resistance.