Issue link: https://hi.iaq.net/i/191637
Climate Change, the Indoor Environment, and Health 160 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH dynamic reservoir of organisms probably serves as the source of aerosol generation, the source of bacteria that can be aspired by predisposed hosts, or both. Thus, indoor water clearly influences Legionella transmission and is itself influenced by regional environmental factors. Pseudomonas aeruginosa Stapleton et al. (2007) studied the incidence and causes of keratitis in contact-lens wearers in Australia. They found that Pseudomonas aeruginosa accounted for a plurality of cases and that it varied with higher mean minimum temperature but not humidity. Conducting their study in a country with well-characterized tropical and more temperate zones, they found that although P. aeruginosa was most common in the tropical regions, gram-positive organisms, such as Staphylococcus aureus, predominated in more temperate regions (Stapleton et al., 2007). Perencevich et al. (2008) studied the effects of seasonal temperature on nosocomial infection rates at the University of Maryland Medical Center. On review of almost 218,594 cases and 26,624 unique cultures, they found that rates of some gramnegative bacillary infections, including P. aeruginosa infections, were higher during warmer months and that rates of P. aeruginosa infection increased in relation to temperature rise. Gram-negative organisms that showed similar seasonal variation included Acinetobacter baumanii, Enterobacter cloacae, and Escherichia coli. Rates of gram-positive bacteria, such as S. aureus and Enterococcus spp., were not increased over the same periods and did not show similar relationships to temperature. Those infections occurred in hospitals, so they are reflections of effects of indoor environment, but they presumably reflect some changes in the outdoor environment as well. That other nosocomial pathogens, such as S. aureus, did not vary in the same pattern excludes simple effects of climate on human practices and suggests a more intrinsic effect of climate on gram-negative nosocomial pathogens. As mentioned above, Perencevich et al. (2008) showed that gramnegative nosocomial infections increased with increasing temperature in Baltimore. In a national survey, McDonald et al. (1999) also found seasonal variation in Acinetobacter baumanii nosocomial infections but not in P. aeruginosa infections. They also noted marked differences in regional rates of A. baumanii infections, with higher rates in the eastern than western parts of the United States. Mycobacteria The Mycobacteriaceae are typically environmentally hardy grampositive rods that include the high-grade primate pathogen Mycobacterium tuberculosis, the more numerous environmental or nontuberculous myco- Copyright © National Academy of Sciences. All rights reserved.