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Appl. Environ. Microbiol., 04 1997, 1557-1563, Vol 63, No. 4
JL Lange, PS Thorne and N Lynch
Current limitations in the methodology for enumeration and identification
of airborne bacteria compromise the precision and accuracy of bioaerosol
exposure assessment. In this study, flow cytometry and fluorescent in situ
hybridization (FISH) were evaluated for the assessment of exposures to
airborne bacteria. Laboratory- generated two-component bioaerosols in
exposures chambers and complex native bioaerosols in swine barns were
sampled with two types of liquid impingers (all-glass impinger-30 and May
3-stage impinger). Aliquots of collection media were processed and
enumerated by a standard culture technique, microscopy, or flow cytometry
after nucleic acid staining with 4',6-diamidino-2-phenylindole (DAPI) and
identified taxonomically by FISH. DAPI-labeled impinger samples yielded
comparable estimates of bioaerosol concentrations when enumerated by
microscopy or flow cytometry. The standard culture method underestimated
bioaerosol concentrations by 2 orders of magnitude when compared to
microscopy or flow cytometry. In the FISH method, aliquots of collection
media were incubated with a probe universally complementary to eubacteria,
a probe specific for several Pseudomonas species, and a probe complementary
to eubacteria for detection of nonspecific binding. With these probes, FISH
allowed quantitative identification of Pseudomonas aeruginosa and
Escherichia coli bioaerosols in the exposure chamber without measurable
nonspecific binding. Impinger samples from the swine barn demonstrated the
efficacy of the FISH method for the identification of eubacteria in a
complex organic dust. This work demonstrates the potential of emerging
molecular techniques to complement traditional methods of bioaerosol
exposure assessment.
Copyright © 1997, American Society for Microbiology
Application of flow cytometry and fluorescent in situ hybridization for assessment of exposures to airborne bacteria
Department of Preventive Medicine & Environmental Health, University of Iowa, Iowa City 52242-5000, USA.
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