Abstract
Purpose:
Pseudomonas aeruginosa associated ocular infections are among the most diverse and difficult to manage. Clinical presentations and pathology range from purulent conjunctivitis and ulcerative keratitis to invasive scleritis and persistent, destructive biomaterial centered infections. Virulence, disease course and patient outcomes are strain specific. We used a combination of molecular, metabolic and in vitro resistance markers to determine and correlate Pseudomonas aeruginosa Type lll effector protein (T3SS) profiles with biochemical patterns, ocular disease presentations and in vitro susceptibility.
Methods:
Type III Profiles: A multiplex PCR was used to characterize and compare the prevalence of exoS (invasive), exoT (invasive), exoU (cytotoxic) and exoY (adenyl cyclase) (genotypes for 155 Pseudomonas aeruginosa strains collected from ocular sources (cornea-n=96, contact lens-n=20, conjunctiva-n=23, lacrimal system-n=8, Intraocular fluids-n=8) from 2008 to 2014. Biochemicals and vitro susceptibility profiles were determined using the Vitek 2 system.
Results:
Exo Y and T effector proteins were detected in all 155 isolates, while exoS ( N=70) and exoU (N=63) were generally mutually exclusive. Prevalence of the four identified genotypes were exoS+U- (45.2%), exoS-U+ (40.6%), exoS+U+ (7%) and exoU-S- (9.7%). ExoU (cytotoxic strain) was the predominant profile of isolates recovered from cornea (46.9%) and contact lens cases (70%) but was evident in all sources. ExoS genotypes were documents in 50% or higher for isolates recovered from conjunctiva (56.5%), intraocular fluids (50%) and lacrimal system (50%). Strains with absence of T3SS effectors were seen most often in isolates associated with conjunctivitis (34.8%).<br /> No significant correlation of metabolic profiles (N=100) were associated with these isolates. Strains with genotype exoS-U+ had the higher MIC90 (1 ug/ml) for ciprofloxacin vs 0.5 ug/ml or less for exoS+U- and exoU-S- . Ciprofloxacin resistance ranged from 1% (cornea) to 6% (conjunctiva). MIC90 for moxifloxacin was 2 ug/ml and ranged from 3% (cornea) to 8% (conjunctiva and lacrimal system).
Conclusions:
Ocular Pseudomonas aeruginosa strains are diverse and associated with specific disease syndromes and antibiotic profiles. Characterizing the T3SS profiles may serve as an important adjunct in understanding the pathology and management of these destructive and recalcitrant infections