An organ culture system for study of adherence of Pseudomonas aeruginosa to normal and wounded corneas.

An organ culture system has been developed to study the adherence of Pseudomonas aeruginosa to unwounded corneas and to corneas healing after a 3 mm central epithelial debridement. The Pseudomonas strain was isolated from a human corneal ulcer; suspensions containing 1 X 10(8) colony-forming units/ml (CFU/ml) of bacteria were incubated with the corneas for the last 30 min of the 18 hr culture period. The distribution pattern and number of adherent bacteria on the ocular surface were determined by morphometric analysis of scanning electron micrographs. Few bacteria (25 +/- 15/mm2) adhered to the apical cells of unwounded corneas. There was a definite region-specific distribution of adherent bacteria on healing corneas. There was a definite region-specific distribution of adherent bacteria on healing corneas. Most bacteria were found on the denuded basal lamina in front of the leading edge of the migrating epithelium (360,700 +/- 49,000/mm2). Appreciable but lower numbers adhered to the apical membrane of leading-edge cells (37,700 +/- 6,100/mm2) and to the central portion of the denuded basal lamina (28,800 +/- 10,700/mm2). No bacteria were found adherent to the apical cells of the stratified epithelium behind the leading edge of the epithelium migrating to cover the wound. A similar region-specific distribution of adherent bacteria was found when corneas were inverted in the bacterial suspension and when corneas were incubated in the bacterial suspension for 15 rather than 30 min. Corneas preincubated with the lectin, succinyl-concanavalin A, showed significantly decreased bacterial adherence, indicating a possible role for mannose moieties of wound surface glycoconjugates in bacterial adherence.