Identificação de fungos carreados por formigas em hospitais terciários do município de Fortaleza-Ceará

Abstract

Studies show that hospitals are propitious sites for the establishment and proliferation of certain insects. This situation is of particular concern because some insects, such as ants, can carry microorganisms on their body surfaces. The aim of this study was evaluate capacity to the ant species present in two tertiary public hospitals in the city of Fortaleza, Ceará, to carry fungi and to establish a correlation with the airborne fungal microbiota. From March 2007 to February 2008, 2,899 ants were evaluated at two hospitals. The ant communities were sampled monthly, during two periods (day and night), by setting out nontoxic baited traps. Along with collection of the ants, the fungi present in the air of the hospital environments were isolated and identified through the passive sedimentation method in Petri dishes containing Sabouraud dextrose agar. To identify the ant species, a sample from each trap was sent to the Entomology Laboratory of State University of Ceará, where the ants captured were classified by morphological criteria. Another sample of the captured ants from each trap was sent to the Specialized Medical Mycology Center of the same university. The mycological identification was done by growth in culture media, seeded and incubated at 26-28ºC for up to 15 days, with identification through macro and micromorphological analysis, biochemical profiling and growth in chromogenic medium. From this study, five genera and thirteen species of ants were identified, from the hospitals’ critical areas (8% of the collected ants) and semi-critical areas (92%), during the daytime (48%) and nighttime (52%) periods. In the mycological analysis, 75% of the ants were fungi carriers, with Tapinoma melanocephalum and species from the genus Pheidole having the most potential as carriers of airborne fungi (75% and 18%, respectively) and yeasts (6% and 1%, respectively). Among the airborne fungi identified, those belonging to the Aspergillus (46%), Penicillium (18.5%) and Cladosporium (7%) genera were most common on the ants’ body surfaces. The predominant yeasts belonged to the Candida genus (70% of those isolated). Comparison of the fungal strains found in the air with those found on the ants did not establish any statistic correlation between the two fungal microbiotas. In summary, ants act as potential vectors of airborne fungi and yeasts, including some pathogenic species. Therefore, vigilance against insects and systematic air monitoring are important measures to ensure the healthfulness of hospital environments.