Recovery Efficiency and Limit of Detection of Aerosolized Bacillus anthracis Sterne from Environmental Surface Samples

After the 2001 anthrax incidents, surface sampling techniques for biological agents were found to be inadequately validated, especially at low surface loadings. We aerosolized Bacillus anthracis Sterne spores within a chamber to achieve very low surface loading (ca. 3, 30, and 200 CFU per 100 cm²)....

Full description

Saved in:
Bibliographic Details
Published in:Applied and Environmental Microbiology 2009-07, Vol.75 (13), p.4297-4306
Main Authors: Estill, Cheryl Fairfield, Baron, Paul A, Beard, Jeremy K, Hein, Misty J, Larsen, Lloyd D, Rose, Laura, Schaefer, Frank W. III, Noble-Wang, Judith, Hodges, Lisa, Lindquist, H.D. Alan, Deye, Gregory J, Arduino, Matthew J
Format: Article
Language:English
Subjects:
Aerosols
Agar
Anthrax
Bacillus anthracis
Bacillus anthracis - isolation & purification
Bacteriological Techniques - methods
Biological and medical sciences
Colony Count, Microbial
Contamination
Environmental Microbiology
Fundamental and applied biological sciences. Psychology
Humans
Methods
Microbiology
Regression analysis
Risk assessment
Sensitivity and Specificity
Steel
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:After the 2001 anthrax incidents, surface sampling techniques for biological agents were found to be inadequately validated, especially at low surface loadings. We aerosolized Bacillus anthracis Sterne spores within a chamber to achieve very low surface loading (ca. 3, 30, and 200 CFU per 100 cm²). Steel and carpet coupons seeded in the chamber were sampled with swab (103 cm²) or wipe or vacuum (929 cm²) surface sampling methods and analyzed at three laboratories. Agar settle plates (60 cm²) were the reference for determining recovery efficiency (RE). The minimum estimated surface concentrations to achieve a 95% response rate based on probit regression were 190, 15, and 44 CFU/100 cm² for sampling steel surfaces and 40, 9.2, and 28 CFU/100 cm² for sampling carpet surfaces with swab, wipe, and vacuum methods, respectively; however, these results should be cautiously interpreted because of high observed variability. Mean REs at the highest surface loading were 5.0%, 18%, and 3.7% on steel and 12%, 23%, and 4.7% on carpet for the swab, wipe, and vacuum methods, respectively. Precision (coefficient of variation) was poor at the lower surface concentrations but improved with increasing surface concentration. The best precision was obtained with wipe samples on carpet, achieving 38% at the highest surface concentration. The wipe sampling method detected B. anthracis at lower estimated surface concentrations and had higher RE and better precision than the other methods. These results may guide investigators to more meaningfully conduct environmental sampling, quantify contamination levels, and conduct risk assessment for humans.
ISSN:0099-2240
1098-5336
1098-6596
DOI:10.1128/AEM.02549-08