Etiology of infectious keratitis

Abstract

Objetives

Analyze the etiology of infectious keratitis in our hospital.

Material and methods

Retrospective study in which the medical records of patients were reviewed in which a keratitis-producing microorganism was detected during the last 9 years (January 2014-December 2022). The sample was obtained by corneal scraping and seeded in non-selective media. Bacterial and fungal identification was carried out by mass spectrometry and viral identification by polymerase chain reaction (PCR). Sensitivity was obtained using disk-plate antibiograms, E-test or broth microdilution systems.

Results

A total of 433 samples of corneal scrapings belonging to 416 patients were processed. Of the total samples, 196 were positive (44,3%). The average age was 55 years, with 51% being women. Regarding the etiology, we found the following isolates: Gram-positive bacteria (N = 83) (44%), highlighting Staphylococcus aureus (N = 33), coagulase-negative staphylococci (N = 26), being Staphylococcus epidermidis the most frequent (N = 19). Gram-negative bacteria (N = 67) (35%), including: Pseudomonas aeruginosa (N = 31), 42% associated with the use of contact lenses and Enterobacterales (N = 16). Anaerobes (N = 19), which 18 isolates were Cutibacterium acnes. Regarding viral etiology (N = 10): herpes simple type 1 (N = 7). Varicella-zoster virus (N = 3). Finally, the fungal etiology (N = 13), highlighting Candida spp. (N = 10).

Conclusions

The main agents of infectious keratitis are Staphylococcus aureus and Pseudomonas aeruginosa. The causative agent was detected in 44,3% of the samples, so microbiological analysis of these samples is highly advisable.