Evaluation of Bioaerosol Samplers for Airborne Escherichia coli carried by poultry litter particles

Authors: NGUYEN, XUAN - University Of Tennessee; ZHAO, YANG - University Of Tennessee; Evans, Jeffrey - Jeff; LIN, JUN - University Of Tennessee; SCHNEIDER, LIESEL - University Of Tennessee; VOY, BRYNN - University Of Tennessee; HAWKINS, SHAWN - University Of Tennessee; Purswell, Joseph - Jody

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary: Pathogenic Escherichia coli (E. coli) frequently inhabit poultry litter and may be transmitted on dust generated from bird activity. Bioaerosol samplers are used to quantify airborne E. coli in dust-based transmission. The objective of this study was to compare the performance of three commonly used bioaerosol samplers for collecting the airborne E. coli attached to dust particles. A system to generate dry bioaerosols was constructed for this this study to use in biological safety cabinet. Under similar environmental conditions and airborne E. coli concentrations, the three samplers measured 5.05±2.08 log10 colony-forming units (CFU) m-3 for the Andersen six-stage impactor, 5.69±1.92 log10 CFU m-3 for AGI-30 ,and 2.94±0.81 log10 CFU m-3 for Bobcat. The results show there is no significant difference between Andersen six-stage impactor and AGI-30, while there was a sizeable decrease in the bacteria concentration detected by the Bobcat sampler. The results also showed that airborne E. coli are found most often on large particles (> 7.0 µm).

Technical Abstract: Pathogenic Escherichia coli (E. coli) are frequently recovered in poultry litter and may be transmitted through the air once dry-based bioaerosols are generated by the dust-bathing behavior of birds. To quantify the airborne E. coli for risk assessment of dry aerosolization-based transmission, efficient bioaerosol samplers under dry aerosolization conditions are required. The objective of this study was to compare the performance of three commonly used bioaerosol samplers, which include an Andersen six-stage impactor, an all-glass impinger (AGI-30) and an ACD-200 Bobcat (Bobcat), for collecting the airborne E. coli attached to dust particles under dry aerosolization condition in a bio-safety chamber. The Andersen six-stage impactor separately collects airborne microorganisms attached to dust particles of different sizes. The AGI-30 is an affordable sampler that collects microorganisms in liquid medium. The Bobcat is a high-volume sampler designed for collecting microorganisms at low concentrations. A dry aerosolization system was designed to generate dry bioaerosols for the study. Under the same airborne E. coli concentration with stable environmental conditions including temperature and relative humidity (RH), the E. coli concentrations determined by the three samplers were 5.05±2.08 log10 colony-forming units (CFU) m-3 for Andersen six-stage impactor, 5.69±1.92 log10 CFU m-3 for AGI-30 and 2.94±0.81 log10 CFU m-3 for Bobcat. The results show there is no significant difference between Andersen six-stage impactor and AGI-30, while there was a sizeable decrease in the bacteria concentration determined in the Bobcat sampler. The results also reported that airborne E. coli are preferentially aggregated on large particles (> 7.0 µm). This study demonstrated a methodology to evaluate bioaerosol sampler efficiency using dry-base carriers of biological agents which are predominant in poultry houses. The optimal sampler can be used to accurately determine the airborne E. coli loading in commercial poultry houses.