Identification Of The Source And Transmission Of Airborne Escherichia Coli And Novel H1N1 Influenza Virus

Microorganisms and their products in bioaerosol from animal houses can cause serious air pollution. They may also affect the health and the production capability of the animals and induce prevalence of aerosol infectious diseases. The polluted air in livestock farms is often associated with the outbreak of the epidemic diseases and the environmental problems. It is known that many airborne pathogen microorganisms, including viruses and bacteria, can spread over a large area through the air. Bioaerosol disseminated from animal houses to their environments has been studied with an emphasis on total bacterium amount, pathogenic bacteria and antibiotic resistances of the bacteria in animal houses and their ambient air. It is difficult to differentiate between two strains that have very close genetic relationship using traditional bacterial taxonomy, and can not get the enough evidence to prove the transmission of microorganism from animal houses to their sorroudings. In recent years, the bacteria classification technologies of molecular biology represented from ERIC-PCR and PFGE(Pulse field gel electrophoresis) were used to identify the bacteria homology.To get in-depth understanding of microbial aerosol development and transmission to the surroundings of a chicken house, using Escherichia coli as indicator bacteria in this study, air samples were collected by the Andersen-Grade 6 Air Microorganism Sampler from air in the 5 chicken houses, and at 10- and 50-m upwind sites and at 10-, 50-, 100-, 200-, and 400-m downwind sites outside of the chicken houses; meanwhile, chicken manure samples were collected to isolate and identify Escherichia coli, and calculate the Escherichia coli concentration (expressed in CFU/m3 air) at each sampling point. Then, for each chicken house, genotyping of Escherichia coli isolates of different origins were carried out by ERIC-PCR, and then homology identification of the strains with ERIC-PCR similarity coefficient >90% was carried out by pulsed field gel electrophoresis (PFGE ), to accurately determine the origin of the strains. The mode of microbial aerosols in a chicken house to transmit to its surroundings was determined, according to changes of Escherichia coli concentrations at each sampling point, as well as genetic distances of Escherichia coli strains isolated at different samplings. With respect to the concentrations, the Escherichia coli concentrations of the 5 chicken houses were 11-56 CFU/m3 air, far higher than those at the upwind and downwind sites outside of the chicken houses, suggesting that microbial aerosols were unceasingly produced and accumulated in the chicken houses. However, there was no significant difference of Escherichia coli concentrations (P>0.05) at the downwind sites with different distances, suggesting that airborne Escherichia coli derived from the chicken houses were possibly transmitted to a certain distance. Homology identification, carried out by the combination of the two methods, i.e. ERIC-PCR and PFGE, showed that, Escherichia coli isolated from chicken manure and some Escherichia coli (17.1%) isolated from air in the chicken houses were of the same origin. The majority of Escherichia coli (59.1%) isolated at the downwind sites (10-, 50-, 100-, and 200-m) outside of a chicken house, and Escherichia coli isolated from chicken manure, were of the same origin. However, Escherichia coli isolated at the upwind sites were of small similarity coefficient (<80%) with Escherichia coli isolated from chicken manure or from air in the chicken houses, suggesting that they were not derived from the chicken houses. Escherichia coli isolated at each downwind sampling point were of low homology with Escherichia coli isolated at 10- and 50-m upwind sites, excluding the possibility that Escherichia coli isolated at downward sites were from the upwind sites. However, most of Escherichia coli isolated from air in the chicken houses and at the downwind sites outside of the chicken houses were of high similarity coefficient (>85%), suggesting that bacteria in chicken manure was able to form into aerosols, and transmit to the surroundings of the chicken houses through air exchange to a different distance based on different meteorological conditions, leading to biological contaminations of surroundings, and transmission of microbial pathogens. Using the combination of ERIC and PFGE in this study, homology analysis of strains with ERIC-PCR similarity coefficients >90% was carried out by PFGE, to obtain more accurate results.The project established a method to detect the novel H1N1 influenza virus by Real-Time RT-PCR with a novel probe provides. We collected 135 samples in 20 pig farms in 5 areas in Shan Dong province. The experiment detected positive samples at the downwind 10m, which indicated the novel H1N1 influenza virus may transmit to the surroundings of the pig farms through air exchange to a different distance. The detection system also provided a powerful technical support for the study of the source, spread and infective dose of H1N1, and was significant for evaluation of public environmental sanitation and early warning of epidemic situation.