Pseudomonas aeruginosa is a common opportunistic bacterial pathogen that causes a variety of infections in humans. Populations of P. aeruginosa are dominated by common clones that can be isolated from diverse clinical and environmental sources. To determine whether specific clones are associated with corneal infection, we used a portable genotyping microarray system to analyze a set of 63 P. aeruginosa isolates from patients with corneal ulcers (keratitis). We then used population analysis to compare the keratitis isolates to a wider collection of P. aeruginosa from various nonocular sources. We identified various markers in a subpopulation of P. aeruginosa associated with keratitis that were in strong disequilibrium with the wider P. aeruginosa population, including oriC, exoU, katN, unmodified flagellin, and the carriage of common genomic islands. The genome sequencing of a keratitis isolate (39016; representing the dominant serotype O11), which was associated with a prolonged clinical healing time, revealed several genomic islands and prophages within the accessory genome. The PCR amplification screening of all 63 keratitis isolates, however, provided little evidence for the shared carriage of specific prophages or genomic islands between serotypes. P. aeruginosa twitching motility, due to type IV pili, is implicated in corneal virulence. We demonstrated that 46% of the O11 keratitis isolates, including 39016, carry a distinctive pilA, encoding the pilin of type IV pili. Thus, the keratitis isolates were associated with specific characteristics, indicating that a subpopulation of P. aeruginosa is adapted to cause corneal infection.Pseudomonas aeruginosa is a common infective cause of corneal ulceration (bacterial keratitis) (14,32,54). P. aeruginosa keratitis is frequently associated with contact lens wear (54), because hypoxia and trauma from the contact lens allows bacterial adhesion, and as the bacterium is a common contaminant of moist areas such as a contact lens case, the exposure of the ocular surface to the bacterium can easily occur. Subsequently, a combination of P. aeruginosa virulence factors and damage to host ocular defenses allows infection to develop. The host immune and inflammatory responses then contribute both to the elimination of the bacteria and to associated damage to tissues (14). P. aeruginosa is an opportunistic pathogen that is capable of causing a range of infections (16, 38), and it carries an impressive array of virulence factors. The virulence factors implicated in keratitis include twitching motility associated with type IV pili (63), flagella (13), a type III secretion system (22), and quorum-sensing regulated exoproducts (58).The genome of P. aeruginosa consists of core genes (approximately 90%) and accessory genes (approximately 10%) (40).The core genome, carried by all strains of P. aeruginosa, includes many of the recognized virulence genes (61). However, some strain-variable virulence-associated genes also occur, often clustered within genomic islands (3,33,47,50,60,61)....

In vascularized organ transplants, gender mismatches have higher rates of immunological rejection. We investigated the influence of gender incompatibility, including H‐Y incompatibility, on corneal transplant graft rejection and failure. Patients were included who had undergone a first corneal transplant for keratoconus (KC), Fuchs endothelial dystrophy (FED), pseudophakic bullous keratopathy (PBK), infection and other indications. A Cox regression model was fitted for each indication to determine factors affecting graft failure and rejection at 5 years. The impact of gender, including H‐Y, matching was analyzed after accounting for other factors, including known risk factors. Of 18 171 patients, 4314 had undergone a transplant for FED, 4783 for KC, 3669 for PBK, 1903 for infection and 3502 for other disorders. H‐Y mismatched (male [M]→female [F]) corneas were at greater risk of graft failure or rejection. For FED, F→F were 40% less likely to fail (p < 0.0001) and 30% less likely to reject (p = 0.01); M→M were 20% less likely to fail (p = 0.04) and 30% less likely to reject (p = 0.01). For KC, M→M matched corneas were 30% less likely to fail (p = 0.05) and 20% less likely to reject (p = 0.01) compared with H‐Y mismatches. H‐Y antigen mismatched (M→F) patients were at greater risk of rejection or graft failure.

Nitisinone, although unapproved for use in alkaptonuria (AKU), is currently the only homogentisic acid lowering therapy with a potential to modify disease progression in AKU. Therefore, safe use of nitisinone off-label requires identifying and managing tyrosine keratopathy. A 22-year-old male with AKU commenced 2 mg daily nitisinone after full assessment. He was issued an alert card explaining potential ocular symptoms such as red eye, tearing, ocular pain and visual impairment and how to manage them. On his first and second annual follow-up visits to the National Alkaptonuria Centre (NAC), there was no corneal keratopathy on slit lamp examination. On his third follow-up annual visit to the NAC, he was found to have typical dendritiform corneal keratopathy in both eyes which was asymptomatic. Nitisinone was suspended until a repeat slit lamp examination, 2 weeks later, confirmed that the keratopathy had resolved. He recommenced nitisinone 2 mg daily with a stricter low protein diet. On his fourth annual follow-up visit to the NAC, a routine slit lamp examination showed mild corneal keratopathy in the left eye. This is despite him reporting no ocular symptoms. This case highlights the fact that corneal keratopathy can occur without symptoms and any monitoring plan with off-label use of nitisinone in AKU will need to take this possibility into account. This is also the first time that typical corneal keratopathy has been described with the use of low dose nitisinone in AKU without symptoms.