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Infect Control Hosp Epidemiol. 2007 Sep;28(9):1066-70. Epub 2007 Jul 6.

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.

Author information

1
Department of Environmental Health and Safety, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77230, USA. ldlee@mdanderson.org

Abstract

OBJECTIVE:

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.

DESIGN:

Detailed environmental assessment.

SETTING:

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

METHODS:

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.

RESULTS:

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/m(3); P=.33).

CONCLUSIONS:

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 re-entrained bioaerosols (ie, those suspended by activity in the room) after cleaning and the risk of nosocomial invasive aspergillosis.

PMID:
17932828
DOI:
10.1086/519866
[Indexed for MEDLINE]

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