Etiology of infectious keratitis

Analyze the etiology of infectious keratitis in our hospital.

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.

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).

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.