Relationship between environmental fungal contamination and the incidence of invasive aspergillosis in haematology patients.

Invasive aspergillosis (IA) is a major opportunistic infection in haematology patients. Spore inhalation is the usual route of Aspergillus infection, suggesting a determining role of environmental contamination by spores in the epidemiology of IA. We prospectively examined the relationship between environmental contamination by Aspergillus and other fungal species and the incidence of invasive nosocomial aspergillosis (INA) in a bone marrow transplantation unit and two haematology wards. During a four-year period, levels of air and surface fungal contamination were determined bi-monthly in patients' rooms (some equipped with HEPA filters and LAF systems), and various common sites in each ward (corridors, nursing stations, etc.). Results were compared to the incidence of INA. A total of 3100 air and 9800 surface samples were collected, and 79 cases of IA were diagnosed, of which 64 were probably or possibly INA. Patterns of fungal contamination were comparable in the three wards, with a gradient ranging from high levels in common sites to a virtual absence in rooms equipped with HEPA filters and LAF systems. Using a regression model, a significant relationship was found between the incidence of INA and the degree of fungal contamination of air and surfaces in conventional patient rooms (not equipped with HEPA) and common sites. This study shows that in a non-epidemic setting, there is a significant relationship between environmental fungal contamination in haematology wards and the incidence of INA. Our findings underline the importance of environmental surveillance and strict application of preventive measures.

Comparative performance of impactor air samplers for quantification of fungal contamination.

The aim of this study was to assess the performance of different impactor air samplers for fungal spore collection in the hospital environment. Four recent impactor air samplers were selected: Samplair (AES, Combourg, France); Air Test Omega (LCB, France); Air Samplair Mas-100 (Merck, France); and BioImpactor 100-08 (AES). They were compared with one another at three different hospital sites with varying levels of contaminated air. No significant difference in the efficiency of spore recovery was found between Air Test Omega, Mas-100 and BioImpactor, whereas Samplair was significantly less efficient. BioImpactor was then selected to represent the three superior impactors and was compared with the single-stage Andersen disposable sampler and the Collectron MD8 air sampler (Sartorius, France) and the High Flow Air Sample (BioTest, France), which are based on filtration and centrifugation methods, respectively. No significant difference was observed in terms of spore recovery. On the basis of their performance, unit sampling cost, autonomy and simplicity of use, we conclude that Air Test Omega, Air Samplair Mas-100 and BioImpactor 100-08 are suitable for routine indoor evaluation of fungal contamination of air in hospitals.

[Mycologic surveillance of the environment for preventive invasive aspergillosis. Proposals for standardization of the methodologies and implementation]. / Surveillance mycologique de l'environnement pour la prévention de l'aspergillose invasive. Propositions de standardisation des méthodologies et des modalités d'application.

A MAJOR RISK: The infection of immunodepressed patients by Aspergillus-type fungi increases morbidity and mortality, particularly in hematology units or during solid organ transplantation. Although present diagnostic means benefit from the progress over the last years, they remain limited and chemoprophylaxis protocols have still not demonstrated significant efficacy. THE NEED FOR RECOMMENDATIONS: Today, the handling of environmental risks is the only strategy that has proved its efficacy and usefulness. On the basis of administrative recommendations and data from the literature, a multicentric and pluri-disciplinary task force, grouping clinicians, microbiologists and hygienists, has assessed different methods and has proposed recommendations for the standardization and optimization of fungal surveillance of the environment.

Fungal contamination of food in hematology units.

The prevalence of thermotolerant fungi on non-heat-sterilizable food was determined. Aspergillus spp. were noted in 100% of pepper and regular tea samples, 12 to 66% of fruits, 27% of herbal teas, and 20% of freeze-dried soup samples. All soft cheese samples were contaminated by Geotrichum and yeast (Candida norvegensis) but Candida albicans was never identified.