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Survival of mycobacteria on N95 personal respirators.

Authors
Reponen-TA; Wang-Z; Willeke-K; Grinshpun-SA
Source
Infect Control Hosp Epidemiol 1999 Apr; 20(4):237-241
NIOSHTIC No.
20031345
Abstract
OBJECTIVES: The overall aim of this study was to investigate the survival and possible growth of Mycobacterium tuberculosis simulant bacteria on respirator filters. METHODS: Mycobacterium smegmatis was used as a biochemical simulant for M tuberculosis. Bacterial survival was tested on National Institute for Occupational Safety and Health-certified N95 respirators from three manufacturers. The first experiments simulated one-time respirator use and subsequent storage for 1 to 9 days under ideal conditions for the growth of mycobacteria: 37 degrees C and 85% relative humidity. The bacteria were loaded on the respirator filters under three different nutritional conditions: in the absence of nutrients; in the presence of human saliva (simulating conditions when the respirator is worn); and in the presence of nutrient broth (for ideal growth potential). The subsequent experiments simulated respirator wear for 2 hours under medium work-load conditions at a breathing rate of 56 L/min. RESULTS: It was found that M smegmatis did not grow on the tested respirators, even when the respirators were stored at temperature, humidity, and nutrition conditions most favorable for microbial growth. However, these bacteria could survive on respirators for up to 3 days during storage. The culturability of M smegmatis was not affected by airflow that simulated the breathing rate associated with medium work-load conditions for 2 hours. CONCLUSIONS: This study shows that M tuberculosis surrogate bacteria collected on a respirator are not able to grow and are able to survive only in ideal (ie, not clinically relevant) conditions. Based on these experiments, we conclude that M tuberculosis is unlikely ever to become an infectious problem in the air again, once it is removed by a respirator.
Keywords
Respirators; Health-care; Bacteria; Bacterial-dusts; Microbial-test-systems; Filters; Filtration; Environmental-factors; Airborne-dusts; Airborne-particles
Contact
Tiina Reponen, PhD, Aerosol Research and Exposure Assessment Laboratory, Department of Environmental Health, University of Cincinnati, PO Box 670056, Cincinnati, OH 45267-0056
CODEN
ICEPE3
Publication Date
19990401
Document Type
Journal Article
Funding Amount
746102
Funding Type
Grant
Fiscal Year
1999
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-003244
Issue of Publication
4
ISSN
0899-823X
Source Name
Infection Control and Hospital Epidemiology
State
OH
Performing Organization
University of Cincinnati, Cincinnati, OH
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