Characterization of a possible nosocomial aspergillosis outbreak

Objective To study the epidemiologic aspects of a suspected outbreak of nos ocomial invasive aspergillosis. Methods Sixteen Aspergillus fumigatus strains were isolated from bronchoalv eolar washings or sputa of 10 patients during a 9-month period. Furthermore , two environmental samples, isolated in a microbiological screening of the hospital, were also available for analysis. Random amplified polymorphic D NA analysis (RAPD) was carried out. Results The analysis performed by RAPD clearly demonstrated substantial gen etic variation among the isolates. Both of the two different primers select ed for RAPD analysis (R-108 and AP12h) were able to demonstrate that the st rains isolated from all patients infected with the same fungal species and the environmental samples were genotypically distinct. The results by RAPD typing demonstrated that this technique could detect variability among isol ates of Aspergillus fumigatus from different patients and even from the sam e patient. Conclusions RAPD genotyping proved that the outbreak of invasive aspergillo sis consisted of a series of events, non-related, and probably not coming f rom the same source within the hospital. This type of analysis is an easy, quick and highly discriminatory technique that may help in planning epidemi ologic studies of aspergillosis.