Etiology of infectious keratitis

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.