The role of type III secretion system and lens material on adhesion of Pseudomonas aeruginosa to contact lenses.
OBJECTIVE
To determine the distribution of invasive and cytotoxic genotypes among ocular isolates of P. aeruginosa and investigate the influence of the type III secretion system (T3SS) on adhesion to conventional, cosmetic, and silicone hydrogel contact lenses (CL).


METHODS
Clinical isolates from 2001 to 2010 were analyzed by multiplex PCR for exoS, exoU, and exoT genes. Bacterial adhesion to etafilcon, nelfilcon (gray colored), balafilcon, and galyfilcon CL with or without artificial tear fluid (ATF) incubation were compared. Surface characteristics were determined with scanning electron microscopy (SEM).


RESULTS
Among 87 total isolates, 64 strains were from microbial keratitis cases. CL-related microbial keratitis (CLMK) isolates were mostly of the cytotoxic genotype (expressing exoU) (P = 0.002). No significant differences were found in bacterial adhesion to all types of CL between the genotypes under T3SS-inducing conditions. A trend for least bacterial adhesion of galyfilcon compared to the other CL was noted for both genotypes. Needle complex pscC mutants adhered less to all materials than the wild type (P < 0.05), indicating a role of the T3SS in contact lens adhesion. ATF-incubated CL had significantly more bacterial adhesion (P < 0.05). SEM showed most of the bacteria adhering on CL surfaces.


CONCLUSIONS
CLMK isolates were mostly of cytotoxic genotype. Different genotypes did not significantly differ in its adhesion to various CL. T3SS and other adhesins are involved in bacteria-contact lens adhesion through complex interactions. Contact lens materials may also play an important role in the adherence of both genotypes of P. aeruginosa.
Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan.
Elizabeth P
EP
Shen
Ruey-Yug
RY
Tsay
Jean-San
JS
Chia
Semon
S
Wu
Jing-Wen
JW
Lee
Fung-Rong
FR
Hu
D036002:ADP Ribose Transferases / Q000235:genetics / Q000378:metabolism; D001422:Bacterial Adhesion / Q000235:genetics / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics; D003263:Contact Lenses, Hydrophilic / Q000382:microbiology*; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D020100:Hydrogels; D007634:Keratitis / Q000378:metabolism / Q000382:microbiology*; D008689:Methacrylates; D016296:Mutagenesis / Q000502:physiology; D009883:Ophthalmic Solutions; D011552:Pseudomonas Infections / Q000378:metabolism / Q000382:microbiology*; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D055571:Secretory Pathway / Q000235:genetics / Q000502:physiology*; D012828:Silicones; D014774:Virulence / Q000235:genetics
D001426:Bacterial Proteins; D001427:Bacterial Toxins; C477521:ExoT protein, Pseudomonas aeruginosa; D020690:GTPase-Activating Proteins; D020100:Hydrogels; D008689:Methacrylates; D009883:Ophthalmic Solutions; D012828:Silicones; C523195:balafilcon A; C114176:etafilcon; C540499:galyfilcon A; C111749:pseudomonas exoprotein A protein, Pseudomonas aeruginosa; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D036002:ADP Ribose Transferases; C444820:exoenzyme S