Gram-Negative Bacterial Keratitis: Analysis Of Risk Factors, Clinical Characteristics, Management, Treatment Outcomes And Bacteriological Profile (2010-2023)

The aim of this study is to analyze the risk factors, clinical characteristics, management, treatment outcomes and bacteriological profile of culture-proven cases od Gram-negative bacterial keratitis from a large tertiary Corneal Unit in Spain between 2010 and 2023.

Bacterial keratitis rarely occurs in the normal eye because of the human cornea's natural resistance to infection. However, predisposing factors, may alter the defense mechanisms of the ocular surface and permit 
bacteria to invade the cornea. Although the most common pathogenic organisms identified in bacterial keratitis include staphylococci and gram-negative rods (Pseudomonas species), various centers worldwide have identified changing trends on the epidemiology of infective keratitis.

One hundred ninety-one culture-proven cases of Gram-negative bacterial keratitis (178 patients) diagnosed and treated between January 2010 and December 2023 at a tertiary hospital in Spain, were identified and retrpspectively reviewed for ocular and systemic risk factors, treatment modalities, and outcomes, as well as bacterial profile identification, antimicrobial sensitivity and resistance data. Both, the clinical and microbiological records of these patientes, were retrospectively reviewed.

178 subjects had culture-proven Gram-negative bacterial keratitis- The average age was 56.93, 55.62% were male patients. 76 patients had an associated ocular risk factor: 37.64% previous ocular surgery, 37.08% contact lens use. In relation with systemic conditions, 41.57% were older than 65 years, 15.17% had diabetes mellitus, 11.80% alcohol consumption, 2.89% thyroid disease. Microbilogical profile: 36.13% Moraxella sp., 29.32% Pseudomona sp., 12.04% Serratia sp., 5.24% Haemophiulus sp., 3.66% Stenotrophomonas maltophilia, 2.62% Acinetovacter sp., 2.62% Klebsiella sp., 2.09% Neisseria sp., 6.28%  others. Resistance to fluorquinolones, gentamicin and cephalosporin was not seen.

In conclusion, our study provides an updated view of the diagnostic and therapeutic practice patterns of Gram-negative bacterial keratitis in a large tertiary hospital in Spain. It is well-known the geographical disparities related to diferences in socio-economic status and microbiological epidemiology among countries. We consider mandatory to know the microbiological profile of one´s working area in order to optimize anti-infective prescriptions and 
improve patients’ visual prognosis.