Occurrence of Pathogenic and Allergenic Molds in the Outdoor and Indoor Environment of a Major Hospital and Molecular Epidemiology of Aspergillus fumigatus in Kuwait

Aspergilli and other molds are prevalent in the environment and are an important cause of opportunistic infections and seasonal allergies in susceptible patients. This study determined species distribution of various molds in outdoor/indoor air in and around a major hospital and performed antifungal susceptibility testing and molecular fingerprinting of environmental and clinical Aspergillus fumigatus isolates in Kuwait. Sampling for the isolation of molds was performed for a 17-month-period from the water/indoor air of medical/surgical wards/ICUs and outdoor air. Molds were identified by phenotypic characteristics and/or by the PCR-sequencing of rDNA/β-tubulin/calmodulin genes. Antifungal susceptibility testing was done by Etest. Fingerprinting was performed by nine-loci-based microsatellite analysis. A total of 6179 isolates were obtained from outdoor (n = 4406) and indoor (n = 1773) environments. These included Cladosporium spp. (n = 2311), Aspergillus spp. (n = 1327), Penicillium spp. (n = 1325), Paecilomyces spp. (n = 473), Alternaria spp. (n = 218), Bipolaris spp. (n = 133), and other molds (n = 392). Fingerprinting data revealed heterogeneity among clinical and environmental A. fumigatus and shared genotypes among outdoor air and hospital environmental isolates. Itraconazole-resistant A. fumigatus isolates with TR₃₄/L98H mutations in Cyp51A were also recovered from outdoor air (n = 1), a hospital environment (n = 3), and clinical samples (n = 2). More than 15 fungal genera and all four Aspergillus (Nigri, Flavi, Fumigati, and Terrei) sections and nine rare aspergilli were detected. The isolation frequency was higher during the peak allergy season of October/November. The presence of shared genotypes among outdoor air and the hospital environment including triazole-resistant A. fumigatus suggests a reservoir for invasive infections among susceptible hospitalized patients.