[Distribution Characteristics of Antibiotic Resistance Genes in PM2.5 of a Concentrated Broiler Feeding Operation].

Concentrated poultry feeding operations are an important source of antibiotic resistance genes (ARGs). Little attention has been given to PM2.5 as a mechanism for exposing ARGs to humans. In this study, PM2.5 and fecal samples from inside the broiler feeding operation and PM2.5 samples from outside the broiler feeding operation were collected. All samples were subjected to the determination of class Ⅰ integrin (intI1), total bacterial gene (16S rDNA), and 19 ARGs of six types by quantitative real-time PCR (qPCR). The results indicated that, excluding blaGES-1 and blaSHV-1, the remaining 17 ARGs were detected in all six samples. Sulfonamide resistance genes, tetracycline resistance genes, macrolide resistance genes, and aminoglycoside resistance genes were abundant in the feces, reaching 1.04×109-3.27×1010 copies·g-1, while feces was an important source of antibiotic resistance genes in PM2.5 of the broiler feeding operation. There were high abundances of sulfonamide resistance genes and macrolide resistance genes in PM2.5 from inside the broiler feeding operation, reaching (8.9±1.9)×107 copies·m-3 and (5.6±3.1)×107 copies·m-3, respectively. The abundance of ARGs in the PM2.5 samples from inside the broiler feeding operation was significantly higher compared to the outside PM2.5 samples. There was a significant positive correlation between PM2.5 mass concentration and 16S rDNA, intI1, and ARGs abundance, indicating that PM2.5 was the reservoir and disseminator of airborne bacteria, ARGs, and intI1 in the broiler feeding operation. The abundance of intI1 was higher than ARGs among all samples, and the co-occurring relationship between intI1 and ARGs demonstrates the threat of multi-drug resistance, which is harmful to the surrounding air environment and the health of the breeder and poultry.

[Sources and Pollution Characteristics of Antibiotic Resistance Genes and Conditional Pathogenic Bacteria in Concentrated Poultry Feeding Operations].

Concentrated animal feeding operations (CAFOs) is considered a source of airborne human pathogens and antibiotic resistance genes. This study collected fecal samples and corresponding air samples from inside and outside atmospheric environments of layer and broiler feeding operations. We detected the types of 61 genes including five classes of antibiotics antibiotic resistance genes (23 genes of ampicillin, 23 genes of tetracycline, 5 genes of quinolones, 5 genes of sulfonamides and 2 genes of erythromycin), five conditional pathogenic bacteria (Enterococcus, Escherichia coli, Staphylococcus, Campylobacter and Clostridium perfringens) and class1 integron. Quantitative real time PCR was used to analyze concentrations of typical genes with relatively high detection rates. The results indicated that the detection rates of antibiotic resistance genes were 8,7,2,3 and 2. At the same time, two kinds of pathogenic bacteria were detected. The detection rates of the target genes in the air were lower than those of the fecal sample. The total bacterial gene (16S rDNA) concentration in the air of layer and broiler was 106 copies·m-3, and that of the other typical genes was about 104copies·m-3. And the outdoor concentration was much lower than the indoor concentration. The proportions of antibiotic resistance genes and conditional pathogenic bacteria in the air were higher than those in the fecal samples and the outdoor proportions were lower than the indoor proportions. Preliminary results of this study indicated that feces was an important source of antibiotic resistance genes, conditional pathogenic bacteria and class1 integron. Aerosolization degrees of genes in feces were different. This study will provide the basic data for both source tracking of antibiotic resistance genes and pathogens from CAFOs and risk assessment of pollution of CAFOs in the surrounding air environment.