Factors Affecting Microbiological Colony Count Accuracy for Bioaerosol Sampling and Analysis

Details

• Personal Author:
  Chang W ; Clark S ; Donnelly J ; Grinshpun SA ; Juozaitis A ; Macher JM ; Willeke K
• Description:
  The effects of bacterial spore surface density, nutrient concentration in culture medium, sample incubation time and ability of an observation system to identify overlapped colonies on colony masking were investigated using Bacillus-subtilis. A suspension of B-subtilis spores was aerosolized, and the aerosol was sampled using a slit to agar (STA) impactor. Colonies were counted after 12 and 36 hours of incubation. The results indicated that the degree of bacterial colony masking depended on colony density on a collection surface, on colony diameter, and on the ability of an observation system to distinguish overlapped colonies. Colony surface density depended directly on four factors, including bioaerosol concentration in the sampled air, sampler airflow rate, small collection time, and collection surface area. Colony surface density depended indirectly on nutrient concentration and incubation conditions. Colony diameter depended on nutrient concentration, incubation time and temperature, and colony surface density. Colony size was also a function of the specific organism studied and its growth rate and pattern. The occurrence of colony masking for STA impaction samplers, which results in an underestimation of actual colony count, increased with increasing colony surface density and diameter and with decreased ability to distinguish overlapped colonies. The authors offer a method to determine appropriate sample collection time to limit surface density of collected microorganisms and thereby reduce colony masking. [Description provided by NIOSH]
• Subjects:
  Aerosols Microbiology Occupational Health Respiratory Protective Devices Safety
• Keywords:
  Aerosol-sampling Air-quality-control Bacteria Microorganisms NIOSH-Grant NIOSH-Publication Respirators Sampling-methods
• ISSN:
  0002-8894
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Journal Article
• Place as Subject:
  Ohio ; OSHA Region 5
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  56
• Issue:
  10
• NIOSHTIC Number:
  nn:00238262
• Citation:
  Am Ind Hyg Assoc J 1995 Oct; 56(10):979-986
• Contact Point Address:
  Environmental Health University of Cincinnati 3223 Eden Avenue Cincinnati, OH 45267-0056
• Federal Fiscal Year:
  1996
• NORA Priority Area:
  Respirator Research
• Performing Organization:
  University of Cincinnati, Cincinnati, Ohio
• Peer Reviewed:
  True
• Start Date:
  19920901
• Source Full Name:
  American Industrial Hygiene Association Journal
• End Date:
  19950831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:2735fe2d11ea57ca99ab3ddd26c9cae0a8ab2fab637c1029a9f2a3fd661a385a4369edbd092d01049a36336c59761d24fbfe505bec450657ed1e04e16785ac34
• Download URL:
  https://stacks.cdc.gov/view/cdc/197916/cdc_197916_DS1.pdf
• File Type:
  [PDF - 978.72 KB ]