Twelve-year analysis of microbial keratitis trends at a UK tertiary hospital

PurposeTo investigate the frequencies, trends, and in vitro drug susceptibilities of the causative pathogens in microbial keratitis in Manchester Royal Eye Hospital.Patients and methodsCorneal scrape results recorded by the microbiology service between 2004 and 2015 were extracted from an established database. A total of 4229 corneal scrape specimens were identified from an established database. First-line antibiotic treatment in our centre during the study period was ofloxacin and second line was cefuroxime and gentamicin.ResultsMean age was 45.9±21.0. A total of 1379 samples (32.6%) were culture positive. One hundred forty-eight (10.7%) specimens cultured multiple organisms. Of the 1539 organisms identified, 63.3% were Gram-positive bacteria, 27.3% Gram-negative bacteria, 7.1% fungi, and 2.3% Acanthamoebae. A decreasing trend in Gram-positive isolates was found together with a stable trend in Gram negatives and an increasing trend in Acanthamoeba and fungi. There appeared to be a significant increasing trend of Moraxella infection (P=0.001). In all, 83.1 and 90.8% of Gram-positive and -negative isolates tested were susceptible to ofloxacin, respectively. Cefuroxime covered 86.6% of Gram-positive and 61.4% of Gram-negative isolates, whereas gentamicin covered 88.8 and 96.5% of Gram-positive and -negative isolates, respectively.ConclusionWe found a change in the type of Gram-negative organisms isolated over time, with the Moraxella species on the rise. Reassuringly, no significant increase in resistance was observed in vitro for any of the commonly used antibiotics. Ofloxacin remains a good first-line antibiotic treatment but duo-therapy does have broader coverage and should be considered in non-responsive cases.