Microorganisms causing keratitis at a Spanish teaching hospital

A. Blanco Suárez*, D. Domingo García, C. Sánchez Tomero, T. Alarcón Cavero, M. López-Brea


Introduction: Keratitis is a corneal ephitelium infection, which can rarely affect some other cornel layers. Bacterial or fungical ethiology are the most common in keratitis, which is 6 times more common among contact lenses users. Objective: The aim of this document is to describe the isolates found in corneal scrapes obtained from patients suffering of keratitis in the last 4 years at the Microbiology department in tertiary care teaching hospital. Methods: Corneal scrapes, obtained with sterile needle, were directly plated onto both chocolate and blood agar as well as thioglycollate media, after which they were immediately transported to the laboratory and incubated (37ºC, 5%CO2 atmosphere for chocolate agar and 37ºC, regular atmosphere, in the case of blood agar and thioglycollate media). The plates were kept in these conditions for 15 days, looking everyday for possible growth. Identification and susceptibility testing were performed using conventional methodology with MicroScan (Siemens) and API (BioMerieux). Results: In a total of 215 samples, we found 132 (61,4%) negative and 83 (38,60%) positive cultures. Of the positive ones we found 15 coagulase-negative staphilococci (9 Staphylococcus epidermidis, 2 S. homini-homini and 1 S. simulans, 12 Bacillus spp., 9 Propionibacterium acnes, 8 Streptococcus spp. (3 S. oralis, 3 S. pneumoniae, 1 viridans group streptococci and 1 S. mitis), 7 Pseudomonas aeruginosa (1 of them imipenem resistant), 7 Staphylococcus aureus (1 of them MRSA), 6 Corynebacterium spp., 5 Candida spp. (3 C. albicans and 1 C. parapsilosis), 3 Moraxella spp., 2 Enterococcus faecalis, 2 Klebsiella spp. (1 K, pneumoniae and 1 K. oxytoca), 1 Aspergillus sp., 1 Escherichia coli ESBL, 1 Micrococcus sp., 1 Neisseria sp., 1 Pasteurella sp. and 2 Gram-negative unidentified bacilli. Conclusion: Based on our results, we conclude that corneal scrape is a good sample to isolate the microorganisms causing keratitis, considering the high percentage (38.60%) of positive cultures. The most common microorganisms isolated in corneal scrapes from patients suffering of keratitis are coagulase-negative staphylocci, while other skin-related microorganism (Propionibacterium acnes) is the second most abundant isolate. It’s also remarkable that 3 out of 83 positive samples (3.61%) were multi-resistant bacteria.

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23rd European Congress of Clinical Microbiology and Infectious Diseases