POTENTIAL SOURCES OF BACTERIA THAT ARE ISOLATED FROM CONTACT-LENSES DURING WEAR

Purpose. The aim of this paper was to determine the possible contamina tion sources of contact lenses during wear. Methods. Potential sources of the microbiota that colonized hydrogel contact lenses during, wear were examined, The microorganisms that colonize contact lenses were g rown, identified, and compared to those microorganisms that colonized the lower lid margins, upper bulbar conjunctiva, hands, and contact le ns cases of contact lens wearers. In addition, the incidence of contam ination of the domestic water supply in the Sydney area was obtained, and this was compared to the incidence of colonization of contact lens es by microorganisms in general and gram-negative bacteria in particul ar. Results. There was a wide diversity of bacteria that were isolated from each site sampled, Coagulase-negative staphylococci and Propioni bacterium spp, were the most common isolates from all ocular sites exa mined, and constituted the normal ocular microbiota. Other bacteria, i ncluding members of the families Enterobacteriaceae and Pseudomonadace ae, were isolated infrequently from all sites, but most frequently fro m contact lens cases, Statistical analysis revealed that there was a c orrelation between the isolation of bacteria from the contact lens and the lower lid margin (p < 0.001), Analysis of this correlation reveal ed that this was true for the normal microbiota, A correlation was als o noted between the colonization of contact lenses by gram-negative ba cteria and contamination of the domestic water supply. Discussion. Thi s study has demonstrated that the likely route for the normal ocular m icrobiota colonizing contact lenses is via the lid margins, whereas co lonization by gram-negative bacteria, including potential agents of mi crobial keratitis, is likely to be from the domestic water supply.