Density and Molecular Epidemiology of Aspergillus in Air and Relationship to Outbreaks of Aspergillus Infection

Abstract

After five patients were diagnosed with nosocomial invasive aspergillosis caused by Aspergillus fumigatus andA. flavus, a 14-month surveillance program for pathogenic and nonpathogenic fungal conidia in the air within and outside the University Hospital in Rotterdam (The Netherlands) was begun. A. fumigatus isolates obtained from the Department of Hematology were studied for genetic relatedness by randomly amplified polymorphic DNA (RAPD) analysis. This was repeated with A. fumigatus isolates contaminating culture media in the microbiology laboratory. The density of the conidia of nonpathogenic fungi in the outside air showed a seasonal variation: higher densities were measured during the summer, while lower densities were determined during the fall and winter. Hardly any variation was found in the numbers of Aspergillus conidia. We found decreasing numbers of conidia when comparing air from outside the hospital to that inside the hospital and when comparing open areas within the hospital to the closed department of hematology. The increase in the number of patients with invasive aspergillosis could not be explained by an increase in the number ofAspergillus conidia in the outside air. The short-term presence of A. flavus can only be explained by the presence of a point source, which was probably patient related. Genotyping A. fumigatus isolates from the department of hematology showed that clonally related isolates were persistently present for more than 1 year. Clinical isolates of A. fumigatus obtained during the outbreak period were different from these persistent clones. A. fumigatus isolates contaminating culture media were all genotypically identical, indicating a causative point source. Knowledge of the epidemiology of Aspergillus species is necessary for the development of strategies to prevent invasive aspergillosis. RAPD fingerprinting of Aspergillus isolates can help to determine the cause of an outbreak of invasive aspergillosis.

Invasive aspergillosis: epidemiology and environmental study in haematology patients (Sfax, Tunisia)

“…The CFU was increased in summer as reported by other studies. 18,19 In contrast, Goodley et al [20] did not report seasonal variations.…”

Isolation of clinically relevant fungal species from solid waste and environment of dental health services

“…Other studies encountered Aspergillus spp. as the most frequent genus (Leenders et al 1999;Augustowska and Dutkiewicz 2006). Differences among the published data may be expected because of differences in geographical location, climate characteristics, season of the year, presence of accumulated dust, carbon dioxide concentration, presence of air conditioning system and other conditions.…”

Disseminated aspergillosis due to Aspergillus flavus in an experimental model: efficacy of azole therapy

“…In contrast, Pandita et al 13 observed only 25% mortality in quail chickens challenged intratracheally by conidia of A. flavus. These conflicting results, and the dearth of experimental studies on disseminated aspergillosis caused by A. flavus, although this species is frequently implicated in this condition 1,28,29 , prompted our attempt to develop and to characterize an experimental model of disseminated aspergillosis caused by A. flavus.…”

“…Fungi of the genus Aspergillus are ubiquitous, and their conidia abound in relatively uniform numbers in the outside air throughout the year. 1 Inhalation of these airborne conidia by immunocompromised patients, such as those with haematological malignancies or those undergoing liver transplantation, may result in severe disseminated disease. 2,3 In fact, the predominant cause of visceral mycoses in Japan in the period 1991-94 was found to be Aspergillus spp.…”