RESEARCH PAPER
BACTERIAL CONTAMINATION OF INDOOR AIR, SURFACES, AND SETTLED DUST, AND RELATED DUST ENDOTOXIN CONCENTRATIONS IN HEALTHY OFFICE BUILDINGS
 
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1
Pharmaceutical Microbiology and Hygiene Laboratory, Institute of Pharmacy, Free University, Brussels, Belgium
2
Clinic of Allergology and Respiratory Diseases, Saint-Pierre University Hospital, Free University, Brussels, Belgium
3
Department of Biostatistics, School of Public Health, Free University, Brussels, Belgium
4
Biocontaminats Unit, School of Public Health, Free University, Brussels, Belgium
CORRESPONDING AUTHOR
Michel Devleeschouwer   

Université Libre de Bruxelles, Campus Plaine, Laboratoire de Microbiologie Pharmaceutique et d’Hygiène, CP 205/2, Boulevard du Triomphe, B-1050 Bruxelles, Belgique
 
Ann Agric Environ Med. 2005;12(2):187–192
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ABSTRACT
Endotoxin, a characteristic external fraction of the outer membrane from Gram-negative bacteria, continuously shed into the environment, is considered as an important risk factor for human health. Our purpose was to study the bacterial species contaminating healthy working environments. Airborne, working surfaces and carpet dust samples were collected from 25 offices. Bacterial species were identified with biochemical ApiSystem® strips. Endotoxin concentrations in settled dust were measured with the kinetic chromogenic Limulus assay. The airborne bacterial level varied from 44–2,511, with a median of 277 cfu/m3. Bacterial contamination on surfaces ranged from 1–1000, with 33 cfu/25 cm2 as median value. On carpets, bacterial concentration ranged from 0.73–185 × 105 cfu/g, with 7.28 × 105 cfu/g as median value. Endotoxin concentration varied from 4.6–116.2 EU/mg, with a median of 20.3 EU/mg. Altogether, 501 bacterial strains were isolated. The species variability was greater in Gram-negative bacteria than in Gram-positive cocci with 41 versus 34 various species. In conclusion, people working in healthy offices can be exposed to large concentrations of airborne and dust bacteria and related endotoxin concentrations, giving a risk of work-related diseases.
eISSN:1898-2263
ISSN:1232-1966