Evaluation of bioaerosol samplers for collecting airborne <i>E. coli</i> carried by dust particles from poultry litter

Abstract

<b><sc>Abstract.</sc></b> The pathogenic Escherichia coli (E. coli) has been frequently recovered in poultry litter and may be transmitted through the air once bioaerosols are generated by the foraging behavior of birds. To quantify the airborne E. coli for risk assessment of transmission, efficient bioaerosol samplers are required. The objective of this study was to compare the performances of three 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 in an aerosolization 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. Under the same airborne E. coli concentration with stable environmental conditions including temperature and relative humidity (RH), the E. coli concentration determined by the three samplers were 5.05±2.08 log₁₀ CFU m^-3 for Andersen six-stage, 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 and AGI-30, while there was a sizeable decrease in the bacteria concentration determined in the BOBCAT sampler. This study also demonstrated a methodology to evaluate bioaerosol sampler efficiency using dry-base carriers of biological agents which are predominant. The optimal sampler can be used to accurately determine the airborne E. coli loading in commercial poultry houses.