Exposure potential of other common Penicillium species in indoor environments

Abstract

Rationale Penicillium, a fungal genus with about 600 described species, is considered an important allergen source. However, only 4 species, P. brevicompactum, P. chrysogenum, P. citrinum, and P. oxalicum have been characterized for allergen content. We examined the frequency of individual Penicillium species in environmental samples to determine the relevance of currently available allergens. Methods A total of 1768 culturable air and 1547 surface culture samples were examined from homes and adjacent outdoor environments throughout the United States. All Penicillium species were identified using Pitt's morphologically based taxonomy. Percent frequency of occurrence was calculated for 24 Penicillium species. Results Within culturable air samples, the most frequent Penicillium species were P. brevicompactum with 26%, P. chrysogenum and P. citrinum with 17%, P. purpurogenum with 10%, and P. glabrum with 9%. Within surface cultures, predominant species were, P. chrysogenum and P. citrinum with frequencies of 14.5% each followed by P. brevicompactum and P. aurantiogriseum with 7% and 6% frequency, respectively. The frequency of P. oxalicum was among the lowest with 1.4%. Conclusions The allergens of the three most prevalent Penicillium species have been studied. However, other common species have not been analyzed. Future allergen studies should focus on P. purpurogenum, P. glabrum, and P. aurantiogriseum. This database is also being studied for the relative prevalence of species belonging to the genus Aspergillus.