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F. Stapleton, L. Keay, S. Katiyar, K. Edwards, T. Naduvilath; Causative Organisms and Disease Severity in Contact Lens Related Microbial Keratitis in Australia . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4729.
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© ARVO (1962-2015); The Authors (2016-present)
Causative organisms in contact lens (CL)–related microbial keratitis (MK) include predominantly environmental Gram negative bacteria, and less commonly, Acanthamoeba, Gram positive bacteria and fungi. This study evaluated the relationship between causative organism and disease severity with climatic zone in Australia.
New cases of CL–related MK were detected via a national surveillance study conducted from October 2003–September 2004. A clinical case definition was used and cases were stratified by severity. Six climatic zones were identified: 1. hot humid summer, 2. warm humid summer, 3. hot dry summer, mild winter, 4. hot dry summer, cold winter, 5. warm summer, cool winter, and 6. mild summer, cold winter. Daytime temperature was determined for the geographic location at the time of the event from data obtained from the Bureau of Meteorology.
Data were available for 239 cases, 11 in zone 1, 45 in zone 2, 1 in zone 3, 2 in zone 4, 168 in zone 5 and 12 in zone 6. Disease severity was associated with climatic zone with more severe disease in zones of higher humidity (zones 1 and 2) compared with more temperate cooler zones (zones 5 and 6) (p<0.05). A higher proportion of cases in zones 1 and 2 (24/54, 44%) were associated with environmental microorganisms (environmental Gram negative bacteria, Nocardia spp., fungus and Acanthamoeba spp.) compared with zones 5 and 6 (25/167, 14%, p<0.001). Higher daytime temperatures were associated with recovery of environmental pathogens (p<0.001).
Disease profile differs with climatic zone in CL–related MK. Environmental conditions appear to influence both disease severity and causative organism. Tropical zones and warmer temperatures were associated with MK caused by environmental organisms.
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