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Risk of Bioaerosol Contamination With Aspergillus Species Before and After Cleaning in Rooms Filtered With High-Efficiency Particulate Air Filters That House Patients With Hematologic Malignancy

  • Linda D. Lee (a1), Matthew Berkheiser (a1), Ying Jiang (a2), Brenda Hackett (a2), Ray Y. Hachem (a2), Roy F. Chemaly (a2) and Issam I. Raad (a2)...



To examine the impact of cleaning and directional airflow on environmental contamination with Aspergillus species in hospital rooms filtered with high-efficiency particulate air (HEPA) filters that house patients with hematologic malignancy.


Detailed environmental assessment.


A 475-bed tertiary cancer center in the southern United States.


From April to October 2004, 1,258 surface samples and 627 bioaerosol samples were obtained from 74 HEPA-filtered rooms (in addition, 88 outdoor bioaerosol samples were obtained). Samples were collected from rooms cleaned within 1 hour after patient discharge and from rooms before cleaning. Positive and negative airflows were evaluated using air-current tubes at entrances to patient rooms.


Of 1,258 surface samples, 3.3% were positive for Aspergillus species. Univariate analysis showed no relationship between cleaning status and occurrence of Aspergillus species. Of 627 bioaerosol samples, 7.3% were positive for Aspergillus species. Multiple logistic analysis revealed independently significant associations with detection of Aspergillus species. Cleaned rooms positive for Aspergillus species had a higher geometric mean density of colonies than that of rooms sampled before cleaning (18.9 vs 5.5 colony-forming units [cfu] per cubic meter; P = .0047). Rooms with positive airflow had a detection rate for bioaerosol samples equivalent to that of rooms with negative airflow (7.3% vs 7.8%; P = .8). There was no significant difference in the density of Aspergillus species between rooms with negative airflow and rooms with positive airflow (12.5 vs 8.4 cfu/m3; P = .33).


Concentration of bioaerosol contamination with Aspergillus species was increased in rooms sampled 1 hour after cleaning compared with rooms sampled before cleaning, suggesting a possible correlation between reentrained bioaerosols (ie, those suspended by activity in the room) after cleaning and the risk of nosocomial invasive aspergillosis.


Corresponding author

Executive Director, Dept. of Environmental Health and Safety, The University of Texas M. D. Anderson Cancer Center, PO Box 301439, Unit 713, Houston, TX 77230-1439 (


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