Survival of Escherichia coli in Airborne and Settled Poultry Litter Particles

Abstract

Airborne Escherichia coli (E. coli) in the poultry environment can migrate inside and outside houses through air movement. The airborne E. coli, after settling on surfaces, could be re-aerosolized or picked up by vectors (e.g., caretakers, rodents, transport trucks) for further transmission. To assess the impacts of airborne E. coli transmission among poultry farms, understanding the survivability of the bacteria is necessary. The objective of this study is to determine the survivability of airborne E. coli, settled E. coli, and E. coli in poultry litter under laboratory environmental conditions (22–28 °C with relative humidity of 54–63%). To determine the survivability of airborne E. coli, an AGI-30 bioaerosol sampler (AGI-30) was used to collect the E. coli at 0 and 20 min after the aerosolization. The half-life time of airborne E. coli was then determined by comparing the number of colony-forming units (CFUs) of the two samplings. To determine the survivability of settled E. coli, four sterile Petri dishes were placed on the chamber floor right after the aerosolization to collect settled E. coli. The Petri dishes were then divided into two groups, with each group being quantified for culturable E. coli concentrations and dust particle weight at 24-h intervals. The survivability of settled E. coli was then determined by comparing the number of viable E. coli per milligram settled dust collected in the Petri dishes in the two groups. The survivability of E. coli in the poultry litter sample (for aerosolization) was also determined. Results show that the half-life time of airborne E. coli was 5.7 ± 1.2 min. The survivability of E. coli in poultry litter and settled E. coli were much longer with the half-life time of 15.9 ± 1.3 h and 9.6 ± 1.6 h, respectively. In addition, the size distribution of airborne E. coli attached to dust particles and the size distribution of airborne dust particles were measured by using an Andersen impactor and a dust concentration monitor (DustTrak). Results show that most airborne E. coli (98.89% of total E. coli) were carried by the dust particles with aerodynamic diameter larger than 2.1 µm. The findings of this study may help better understand the fate of E. coli transmitted through the air and settled on surfaces and evaluate the impact of airborne transmission in poultry production.

Effect of Ultraviolet Radiation on Reducing Airborne Escherichia coli Carried by Poultry Litter Particles

“…E. coli strain was cultured at 37 °C, 150 rpm for 24 h in ATCC ® Medium 18 (Tryptic Soy Broth ‘TSB’ and Tryptic Soy Agar ‘TSA’, ATCC, Manassas, VA, USA). The bacterial concentrations of E. coli in the solution after 24 h were determined by the traditional serial dilution process [ 12 , 15 ]. The concentration was approximately 9 log 10 colony-forming unit (log 10 CFU) mL −1 .…”

“…The litter preparation was performed in the same way as in our previous studies [ 12 , 15 ]. Litter was taken from a commercial broiler farm.…”

“…This experiment required 240 g of litter, which was evenly distributed among 40 ceramic cups. In a prior experiment, the capacity to generate airborne dust was examined [ 12 ], and the findings revealed that 240 g of litter put to the mixer produced dust concentrations ranging from 0.9 to 1.1 mg m −3 which is within the average range of dust concentration in a commercial chicken farm [ 16 ]. To prepare litter inoculated with E. coli , a set of 43 ceramic cups (40 cups for experiment plus 3 controls) which were identical in shape was used to hold the litter.…”

“…Specifically, UV with a wavelength of 254 nm showed the highest performance in terms of disinfecting pathogens [ 11 ]. In poultry houses, the airborne E. coli can be carried by dust particles [ 12 , 13 ] that might prevent UV light exposure, and thus the dust particles can protect the airborne E. coli from being irradiated [ 14 ]. In addition, the variation of environmental conditions in poultry houses such as ventilation systems or air flows, temperature, and relative humidity (RH) lead to variable contact time and resistance to UV light.…”

Transmission of antimicrobial resistance (AMR) during animal transport

“…Another study highlighted that the position of the animal in the transport vehicle would have an effect with animals in the nose compartments being less contaminated than those in the deck or belly compartments (Stanford et al., 2011 ). Survival of artificially aerosolised E. coli is limited with a half‐life of 5.7 min; attachment to dust particles will prolong this and may enable transmission of E. coli across compartments within transport vehicles (Nguyen et al., 2022 ).…”