IK is the infection of the clear coverage on the dome of eyes. The study was done to examine the incidence, causative microorganisms and in vitro antimicrobial susceptibility and resistance profiles of infectious keratitis (IK) in Nottingham, UK.
All patients who were diagnosed with IK and underwent corneal scraping between a 12-year period at a UK tertiary referral centre. Relevant data was analysed including demographic factors, microbiological profiles and in vitro antibiotic susceptibility of IK.
The estimated incidence of IK was 34.7 per 100 000 people/year. Of the 1333 corneal scrapes, 502 (37.7%) were culture-positive and 572 causative microorganisms were identified. Sixty (4.5%) cases were of polymicrobial origin (caused by ≥2 different microorganisms). Gram-positive bacteria (308, 53.8%) were most commonly isolated, followed by Gram-negative bacteria (223, 39.0%), acanthamoeba (24, 4.2%) and fungi (17, 3.0%). Pseudomonas aeruginosa (135, 23.6%) was the single most common organism isolated. There was a significant increase in Moraxella spp (p<0.001) and significant decrease in Klebsiella spp (p=0.004) over time. The in vitro susceptibilities of Gram-positive and Gram-negative bacteria to cephalosporin, fluoroquinolone and aminoglycoside were 100.0% and 81.3%, 91.9% and 98.1%, and 95.2% and 98.3%, respectively. An increase in resistance against penicillin was observed in Gram-positive (from 3.5% to 12.7%; p=0.005) and Gram-negative bacteria (from 52.6% to 65.4%; p=0.22).
The study concluded that the IK represents a burden in the UK and the reported incidence is likely underestimated. The recent broad-spectrum antimicrobial treatment is efficient for IK, although challenged by some level of antimicrobial resistance and polymicrobial infection.