The ability to degrade elastine is considered a pathogenic factor of Aspergillus fumigatus, and elastase positive strains could purportedly have an increased pulmonary invasiveness. OBJECTIVE: To correlate the in vitro elastase activity of isolates of Aspergillus fumigatus with their clinically invasive capacity. MATERIAL & METHODS: The origins of 22 Aspergillus fumigatus were: 12 invasive pulmonary aspergillosis (8 heart transplant recipients), 6 colonizers (5 cystic fibrosis, 1 heart transplant recipient), 2 aspergillomas, and 2 obtained from environmental sampling. The isolate was inoculated in the central point of the plaque with elastine, and the diameter of growth and diameter of elastase activity were measured after 10 days of incubation. The relation between the diameters of elastase activity and growth was defined as the elastase activity index (EAI). Isolates with a greater diameter of elastase activity than diameter of growth were considered to have a high pathogenic index. RESULTS: The proportion of Aspergillus fumigatus isolated with a high pathogenic index were: invasive pulmonary aspergillosis (12/12) (100%), colonizers (1/6) (17%), aspergilloma (0/2) (0%), air (0/2) (0%). The remaining isolates had low or no elastase activity. CONCLUSIONS: Our data suggest that elastase activity index may provide a clue of pathogenicity in clinical isolates of Aspergillus fumigatus with uncertain significance.
Full conference title:
38th Interscience Conference on Antimicrobial Agents and Chemotherapy
- ICAAC 38th