Metagenomic insights into the antibiotic resistomes of typical Chinese dairy farm environments

Characteristics and health impacts of bioaerosols in animal barns: A comprehensive study

Bioaerosols produced during animal production have potential adverse effects on the health of workers and animals. Our objective was to investigate characteristics, antibiotic-resistance genes (ARGs), and health risks of bioaerosols in various animal barns. Poultry and swine barns had high concentrations of airborne bacteria (11156 and 10917 CFU/m3, respectively). Acinetobacter, Clostridium sensu stricto, Corynebacterium, Pseudomonas, Psychrobacter, Streptococcus, and Staphylococcus were dominant pathogenic bacteria in animal barns, with Firmicutes being the most abundant bacterial phylum. Based on linear discriminant analysis effect size (LEfSe), there were more discriminative biomarkers in cattle barns than in poultry or swine barns, although the latter had the highest abundance of bacterial pathogens and high abundances of ARGs (including tetM, tetO, tetQ, tetW sul1, sul2, ermA, ermB) and intI1). Based on network analyses, there were higher co-occurrence patterns between bacteria and ARGs in bioaerosol from swine barns. Furthermore, in these barns, relative abundance of bacteria in bioaerosol samples was greatly affected by environmental factors, mainly temperature, relative humidity, and concentrations of CO2, NH3, and PM2.5. This study provided novel data regarding airborne bio-contaminants in animal enclosures and an impetus to improve management to reduce potential health impacts on humans and animals.

Occurrence and dissemination of antibiotic resistance genes in the Yellow River basin: focused on family farms

As an emerging contaminant, antibiotic resistance genes (ARGs) have attracted growing attention, owing to their widespread dissemination and potential risk in the farming environment. However, ARG pollution from family livestock farms in the Yellow River basin, one of the main irrigation water sources in the North China Plain, remains unclear. Herein, we targeted 21 typical family farms to assess the occurrence patterns of ARGs in livestock waste and its influence on ARGs in receiving environment by real-time quantitative PCR (qPCR). Results showed that common ARGs were highly prevalent in family livestock waste, and tet-ARGs and sul-ARGs were the most abundant in these family farms. Most ARG levels in fresh feces of different animals varied, as the trend of chicken farms (broilers > laying hens) > swine farms (piglets > fattening pigs > boars and sows) > cattle farms (dairy cattle > beef cattle). The effect of natural composting on removing ARGs for chicken manure was better than that for cattle manure, while lagoon storage was not effective in removing ARGs from family livestock wastewater. More troublesomely, considerable amounts of ARGs were discharged with manure application, further leading to the ARG increase in farmland soil (up to 58-119 times), which would exert adverse impacts on human health and ecological safety.

Review of antibiotic-resistant bacteria and antibiotic resistance genes within the one health framework

Background: The interdisciplinary One Health (OH) approach recognizes that human, animal, and environmental health are all interconnected. Its ultimate goal is to promote optimal health for all through the exploration of these relationships. Antibiotic resistance (AR) is a public health challenge that has been primarily addressed within the context of human health and clinical settings. However, it has become increasingly evident that antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) that confer resistance are transmitted and circulated within humans, animals, and the environment. Therefore, to effectively address this issue, antibiotic resistance must also be considered an environmental and livestock/wildlife problem. Objective: This review was carried out to provide a broad overview of the existence of ARB and ARGs in One Health settings. Methods: Relevant studies that placed emphasis on ARB and ARGs were reviewed and key findings were accessed that illustrate the importance of One Health as a measure to tackle growing public and environmental threats. Results: In this review, we delve into the complex interplay of the three components of OH in relation to ARB and ARGs. Antibiotics used in animal husbandry and plants to promote growth, treat, and prevent infectious diseases lead to the development of antibiotic-resistant bacteria in animals. These bacteria are transmitted from animals to humans through food and environmental exposure. The environment plays a critical role in the circulation and persistence of antibiotic-resistant bacteria and genes, posing a significant threat to human and animal health. This article also highlights how ARGs are spread in the environment through the transfer of genetic material between bacteria. This transfer can occur naturally or through human activities such as the use of antibiotics in agriculture and waste management practices. Conclusion: It is important to integrate the One Health approach into the public health system to effectively tackle the emergence and spread of ARB and genes that code for resistance to different antibiotics.

Metagenomic analysis for exploring the potential of Lactobacillus yoelii FYL1 to mitigate bacterial diarrhea and changes in the gut microbiota of juvenile yaks

Diarrhea in calves is a common disease that results in poor nutrient absorption, poor growth and early death which leads to productivity and economic losses. Therefore, it is important to explore the methods to reduce diarrhea in yak's calves. Efficacy of lactic acid bacteria (LAB) for improvement of bacterial diarrhea is well recognized. For this purpose, two different doses (107 CFU, 1011 CFU) of Lactobacillus yoelii FYL1 isolated from yaks were fed to juvenile yaks exposed to E. coli O78. After a trial period of ten days fresh feces and intestinal contents of the experimental yaks were collected and metagenomics sequencing was performed. It was found that feeding a high dose of Lactobacillus yoelii FYL1 decreased abundance of phylum Firmicutes in the E. coli O78 infected group whereas, it was high in animals fed low dose of Lactobacillu yoelii FYL1. Results also revealed that counts of bacteria from the family Oscillospiraceae, genus Synergistes and Megasphaera were higher in control group whereas, order Bifidobacteriales and family Bifidobacteriaceae were higher in infected group. It was observed that bacterial counts for Pseudoruminococcus were significantly (P < 0.05) higher in animals of group that were given high dose of Lactobacillus yoelii FYL1 (HLAB). Compared to infected group multiple beneficial bacterial genera such as Deinococus and Clostridium were found higher in the animals that were given a low dose of Lactobacillus yoelii FYL1 (LLAB). The abundance of pathogenic bacterial genera that included Parascardovia, Bacteroides and Methanobrevibacter was decreased (P < 0.05) in the lower dose treated group. The results of functional analysis revealed that animals of LLAB had a higher metabolism of terpenoids and polyketides compared to animals of infected group. Virus annotation also presented a significant inhibitory effect of LLAB on some viruses (P < 0.05). It was concluded that L. yoelii FYL1 had an improved effect on gut microbiota of young yaks infected with E. coli O78. This experiment contributes to establish the positive effects of LAB supplementation while treating diarrhea.

Contribution of Manure-Spreading Operations to Bioaerosols and Antibiotic Resistance Genes' Emission

Manure spreading from farm animals can release antibiotic-resistant bacteria (ARB) carrying antimicrobial resistance genes (ARGs) into the air, posing a potential threat to human and animal health due to the intensive use of antibiotics in the livestock industry. This study analyzed the effect of different manure types and spreading methods on airborne bacterial emissions and antibiotic resistance genes in a controlled setting. Cow, poultry manure, and pig slurry were spread in a confined environment using two types of spreaders (splash plate and dribble bar), and the resulting emissions were collected before, during, and after spreading using high-volume air samplers coupled to a particle counter. Total bacteria, fecal indicators, and a total of 38 different subtypes of ARGs were further quantified by qPCR. Spreading poultry manure resulted in the highest emission rates of total bacteria (10¹¹ 16S gene copies/kg manure spread), Archaea (10⁶ 16S gene copies/kg manure), Enterococcus (10⁵ 16S gene copies/kg manure), and E. coli (10⁴ 16S gene copies/kg manure), followed by cow manure and pig slurry with splash plates and the dribble bar. Manure spreading was associated with the highest rates of airborne aminoglycoside genes for cow and poultry (10⁶ gene copies/kg manure), followed by pig slurry (10⁴ gene copies/kg manure). This study shows that the type of manure and spreading equipment can affect the emission rates of airborne bacteria, and ARGs.