Air-borne Aspergillus spore concentration in a hospital building is not dependent on potted plants or season

Ref ID: 19193

Author:

M. Oberle, M. Reichmuth, C. Ottiger, R. Laffer, H. Fankhauser, T. Bregenzer

Author address:

Aarau, Zurich, Langenthal, Lachen, CH

Full conference title:

23rd European Congress of Clinical Microbiology and
Infectious Diseases

Date: 27 April 2014

Abstract:

Objective: Potting plants as a source for Aspergillus and other mould fungi are considered a risk factor for neutropenic patients to develop an invasive fungal infection. Mould fungi were isolated from potting soil but their influence on air-born spore concentration is unknown. We compared the air-borne fungal spore concentration in a building of the Cantonal Hospital of Aarau, Switzerland, before and after the installation of potted plants in the staircase.
Methods: Before and after the installation of plants in the stair case we monitored during one year the concentration of fungal spores in the air. Air was sampled twice weekly by impaction principle on Sabouraud dextrose agar plates at six places in the building. During the second year sampling was also done outside the building. Samples were made in duplicate and plates were incubated at 28°C and at 35°C to grow all culturable moulds and pathogenic Aspergillus, respectively. Grown mould colonies were identified macro- and microscopically to genus level.
Results: Aspergillus spores, the main pathogen for invasive mould infections, showed a median concentration of 2 spores/m^3 (inter-quartile range (IQR) 0 – 4) before and after the plant installation. Aspergillus spores outside was significantly higher (5 spores/m^3, IQR 2 – 10, p < 0.001) but no seasonal variation of the concentration was observed. The indoor concentration of the spores of other mould genera was higher in summer (median of 53 spores/m^3, (IQR) 33 - 100) and lower in winter (11 spores/m^3; IQR 8 - 23). The annual median concentration of these spores was 18 spores/m^3 (IQR 6 - 64) pre-installation and 54 spores/m^3 (IQR 22 - 122) after the installation which is a significant increase (p < 0.001). The median concentration outside of these mould spores was 120 spores/m^3 (IQR 40 - 256) which is significantly higher than the indoor concentration with potted plants (p < 0.001). Conclusion: Our data do not confirm that potted plants are a risk factor for severely neutropenic patients in hospitals since the concentration of aspergillus spores was not affected by the installation of plants. The meaning of other mould spores and their seasonal variability remains to be studied. The main risk for aspergillus infection in neutropenic patients seems to be outside hospital buildings in our climate zone.

Abstract Number: P969

Conference Year: 2013

Link to conference website: http://registration.akm.ch/einsicht.php?XNABSTRACT_ID=164365&XNSPRACHE_ID=2&XNKONGRESS_ID=180&XNMASK

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