Metagenomic Insights into Chicken Gut Antibiotic Resistomes and Microbiomes

Dissecting the gut microbial communities and resistomes of wild rats from different ecological areas in Hong Kong

Antimicrobial resistance (AMR) is one of the top global public health issues shared across all One Health domains. Wild rats, as one of key intersections of the animal and environmental domains, are understudied reservoirs and spreaders for AMR. Our study employed the whole-metagenome shotgun sequencing to characterize the caecal microbiome of wild rats and examine the presence of antimicrobial resistance genes (ARGs) from different ecological areas in Hong Kong. We trapped 88 live rats, belonging to the species of Rattus norvegicus (n=57), R. tanezumi (n=24), and R. andamanensis (n=7), from city regions, livestock farms, and stables of horse-riding schools (referred to as "suburbs"). We identified 9672 ARGs belonging to 29 ARG types and 554 ARG subtypes. Among them, aminoglycosides, macrolide-lincosamide-streptogramin and chloramphenicol, known to be predominant in livestock gut resistome or manure compost were significantly more abundant in rats from livestock farms. Moreover, some ARGs with high-risk levels, including tetM, tetL, floR, mecR1 and lnuA, as well as plasmid-borne ARGs were significantly more abundant in rats from livestock farms than from city regions or suburbs. Furthermore, zoonotic antimicrobial-resistant bacteria (ARB) were detected, including but not limited to, prioritized antimicrobial-resistant Klebsiella pneumoniae, Proteus mirabilis, Escherichia coli, Enterococcus faecium, Acinetobacter baumannii, Campylobacter jejuni, and Staphylococcus aureus. Notably, resistant zoonotic bacteria of Streptococcus suis, Campylobacter coli, and Campylobacter jejuni were more abundant in wild rats from livestock farms. Our findings provides insights into the gut resistomes and zoonotic bacteria in wild rats in Hong Kong, highlighting the potential role of wild rats in the dissemination of ARGs and zoonotic pathogens, especially for those from agricultural settings.

The impact of anthropogenic activities on antimicrobial and heavy metal resistance in aquatic environments

This study investigated the prevalence and co-occurrence of antimicrobial (AMR) and metal resistance (MR) in aquatic environments with different human impacts. Metagenomes from pristine, rural and urban sites in Australia were analyzed with AMR ++ and customized binning pipelines. AMR was present in all environments, while MR was mainly in rural and urban samples. AMR gene diversity was higher in rural and urban sites, exhibiting resistance to more antibiotic classes (n = 10) than the pristine site (n = 4). Metal and multicompound resistance was more frequent in rural (14%) compared to urban samples (5%). Pristine samples lacked multidrug and multicompound resistance and had lower resistance to aminoglycosides and the MLS group. Multiresistance was evidenced by copper and aminocoumarin resistance in rural samples and aminoglycoside and mercury resistance in Pseudomonas in all environments. These findings highlight the impact of human activities on AMR and MR spread, emphasizing the need for environmental monitoring and management.

IMPORTANCE

Antimicrobial resistance (AMR) and metal resistance (MR) are critical global health concerns exacerbated by anthropogenic activities. The intricate mechanism underlying the interaction among anthropogenic activities, microbial communities, and resistance remains enigmatic. We developed novel bioinformatic pipelines to unveil this interaction in three aquatic environments. Our findings demonstrate the presence of specific bacterial communities that drive AMR and MR in rural and urban environments. This study underscores the significance of proper agricultural practices, comprehensive monitoring, and management strategies to reduce anthropogenic impacts on environmental resistance.

Farm-to-fork changes in poultry microbiomes and resistomes in Maputo City, Mozambique

Increasing demand for poultry has spurred poultry production in low- and middle-income countries like Mozambique. Poultry may be an important source of foodborne, antimicrobial-resistant bacteria to consumers in settings with limited water, sanitation, and hygiene infrastructure. The Chicken Exposures and Enteric Pathogens in Children Exposed through Environmental Pathways (ChEEP ChEEP) study was conducted in Maputo City, Mozambique from 2019 to 2021 to quantify enteric pathogen exposures along the supply chain for commercial and local (i.e., scavenger) chicken breeds. Here, we performed metagenomic sequencing of total DNA from banked ChEEP ChEEP samples to characterize fecal and carcass microbiomes and resistome diversity between chicken breeds and along the supply chain. Fecal samples (n = 26) were collected from commercial and local chickens at production sites and markets and carcass (n = 49) and rinse bucket samples (n = 26) from markets. We conducted taxonomic profiling and identified antimicrobial resistance genes (ARGs) from metagenomic sequence data, focusing especially on potential human pathogens and "high-risk" ARGs. We estimated alpha diversity for each sample and compared by site and breed. We estimated Bray-Curtis dissimilarity between samples and examined clustering. We found that commercial and local chickens harbored distinct fecal potential pathogens and resistomes at production and market sites. Many potentially pathogenic bacteria and ARGs present in chicken fecal samples are also present on carcasses sold to consumers. Finally, commercial chicken carcasses contain high-risk ARGs that are not necessarily introduced from chicken feces. These results indicate markets are an important site of exposure to potentially pathogenic bacteria and high-risk ARGs.

IMPORTANCE

While chicken eggs and meat are a critical protein source in low-income settings, antibiotics are routinely fed to chickens with consequences for selection of antimicrobial resistance. Evaluating how poultry gut bacterial communities, including potential human pathogens and high-risk antimicrobial resistance genes, differ from farm to market could help identify where to target interventions to minimize transmission risks to human populations. In this study in Maputo City, Mozambique, we found compositional differences between commercial and local chicken breeds at production and market sites. We also found that while all potentially pathogenic bacteria and many high-risk antimicrobial resistance genes persisted from production and market through processing, some resistance genes were detected on carcass samples only after processing, suggesting human or environmental contamination is occurring within markets. Overall, our findings indicate that open-air markets may represent a critical juncture for human exposures to pathogens and antimicrobial resistance genes from poultry and poultry products.

Decreasing light exposure increases the abundance of antibiotic resistance genes in the cecum and feces of laying hens

The gut microbiome plays a crucial role in maintaining animal health and is influenced by various factors, including light exposure; however, the response in laying hens of the gut microbiome to intermittent light regimes and the related impact on antibiotic resistance genes (ARGs) remain poorly understood. In this study, we divided 20-week-old laying hens into two groups. These groups were exposed to either continuous normal light or intermittent light for 8 weeks. The feces and cecal contents of laying hens were collected for analysis. Metagenomic analysis of both feces and cecal content samples revealed significant shifts in the microbial composition and abundance of ARGs under intermittent light exposure compared to normal light exposure (P < 0.05). Furthermore, metabolomic analysis of the cecal contents revealed substantial alterations in the abundance and composition of ARGs and mobile genetic elements (MGEs) in response to intermittent light exposure (P < 0.05). Network analysis revealed intricate co-occurrence patterns among bacterial communities, metabolites, and ARGs, highlighting correlations between Bacteroidetes species, ARGs, and metabolites. Although certain bacterial species showed differential associations, the dominant bacteria carrying ARGs or MGEs had relatively low numbers, suggesting that other bacterial communities may have had a greater influence on ARG dissemination. Moreover, our observations highlight the crucial role of metabolites as mediators between bacterial communities and ARGs, providing novel insights into the dynamics of antibiotic resistance development. Our findings underscore the impact of intermittent light exposure on ARG proliferation in poultry farming and emphasize interconnections among ARGs, bacterial communities, and metabolic pathways. The results underscore the importance of considering both microbial communities and metabolic processes to understand antibiotic resistance in agricultural settings.

Breaking the Cycle: A Yeast Mannan-Rich Fraction Beneficially Modulates Egg Quality and the Antimicrobial Resistome Associated with Layer Hen Caecal Microbiomes under Commercial Conditions

Antibiotics and antibiotic growth promoters have been extensively employed in poultry farming to enhance growth performance, maintain bird health, improve nutrient uptake efficiency, and mitigate enteric diseases at both sub-therapeutic and therapeutic doses. However, the extensive use of antimicrobials in poultry farming has led to the emergence of antimicrobial resistance (AMR) in microbial reservoirs, representing a significant global public health concern. In response, non-antibiotic dietary interventions, such as yeast mannan-rich fraction (MRF), have emerged as a promising alternative to modulate the gut microbiota and combat the AMR crisis. This study investigated whether a yeast mannan-rich fraction containing feed supplement impacted the performance of laying hens, their microbiomes, and the associated carriage of antimicrobial resistance genes under commercial conditions. High-throughput DNA sequencing was utilised to profile the bacterial community and assess changes in the antibiotic resistance genomes detected in the metagenome, the "resistome", in response to MRF supplementation. It was found that supplementation favourably influenced laying hen performance and microbial composition. Notably, there was a compositional shift in the MRF supplemented group associated with a lower relative abundance of pathobionts, e.g., Escherichia, Brachyspira and Trueperella, and their AMR-encoded genes, relative to beneficial microbes. Overall, the findings further demonstrate the ability of prebiotics to improve laying hen performance through changes associated with their microbiome and resistome.

Antibiotic resistance profiles of gut microbiota across various primate species in Guangxi

Introduction

Understanding the gut microbiota and antibiotic resistance gene (ARG) profiles in non-human primates (NHPs) is crucial for evaluating their potential impact on human health and the environment.

Methods

In this study, we performed metagenomic analysis of 203 primate fecal samples, including nine NHP species and humans, to comprehensively characterize their gut microbiota and ARGs.

Results

Our study reveals the prevailing phyla in primates as Firmicutes, Bacteroidetes, Euryarchaeota, and Proteobacteria. The captive NHPs exhibited higher ARG abundance compared to their wild counterparts, with tetracycline and beta-lactam resistance genes prevailing. Notably, ARG subtypes in Trachypithecus leucocephalus (T. leucocephalus) residing in karst limestone habitats displayed a more dispersed distribution compared to other species. Interestingly, ARG profiles of NHPs clustered based on geographic location and captivity status. Co-occurrence network analysis revealed intricate correlations between ARG subtypes and bacterial taxa. Procrustes analysis unveiled a significant correlation between ARGs and microbial phylogenetic community structure. Taxonomic composition analysis further highlighted differences in microbial abundance among NHPs and humans.

Discussion

Our study underscores the impact of lifestyle and geographical location on NHP gut microbiota and ARGs, providing essential insights into the potential risks posed by NHPs to antibiotic resistance dissemination. This comprehensive analysis enhances our understanding of the interplay between NHPs and the gut resistome, offering a critical reference for future research on antibiotic resistance and host-microbe interactions.

Analysis of Resistance Gene Diversity in the Intestinal Microbiome of Broilers from Two Types of Broiler Farms in Hebei Province, China

The crucial reservoir of antibiotic resistance genes (ARGs) within the chicken intestinal microbiome poses a serious threat to both animal and human health. In China, the overuse of antibiotics has significantly contributed to the proliferation of ARGs in the chicken intestinal microbiome, which is a serious concern. However, there has been relatively little research on the diversity of resistance genes in the chicken intestinal microbiome since the implementation of the National Pilot Work Program for Action to Reduce the Use of Veterinary Antimicrobial Drugs in China. The objective of this study was to analyze the diversity of antibiotic resistance genes carried by the chicken intestinal microbiome in both standard farms (SFs), which implement antibiotic reduction and passed national acceptance, and nonstandard farms (NSFs), which do not implement antibiotic reductions, in Hebei Province. Fresh fecal samples of broiler chickens were collected from SFs (n = 4) and NSF (n = 1) and analyzed using high-throughput qPCR technology. Our findings revealed that all five farms exhibited a wide range of highly abundant ARGs, with a total of 201 ARGs and 7 MGEs detected in all fecal samples. The dominant ARGs identified conferred resistance to aminoglycosides, macrolide-lincosamide-streptomycin B (MLSB), and tetracycline antibiotics. Cellular protection mechanisms were found to be the primary resistance mechanism for these ARGs. The analysis of the co-occurrence network demonstrated a significant positive correlation between the abundance of MGEs and ARGs. The SF samples showed a significantly lower relative abundance of certain ARGs than the NSF samples (p < 0.05). The results of this study show that the abundance of ARGs demonstrated a downward trend after the implementation of the National Pilot Work Program for Action to Reduce the Usage of Veterinary Antimicrobial Drugs in Hebei Province, China.

The Silent Threat: Antimicrobial-Resistant Pathogens in Food-Producing Animals and Their Impact on Public Health

The emergence of antimicrobial resistance (AMR) is a global health problem without geographic boundaries. This increases the risk of complications and, thus, makes it harder to treat infections, which can result in higher healthcare costs and a greater number of deaths. Antimicrobials are often used to treat infections from pathogens in food-producing animals, making them a potential source of AMR. Overuse and misuse of these drugs in animal agriculture can lead to the development of AMR bacteria, which can then be transmitted to humans through contaminated food or direct contact. It is therefore essential to take multifaceted, comprehensive, and integrated measures, following the One Health approach. To address this issue, many countries have implemented regulations to limit antimicrobial use. To our knowledge, there are previous studies based on AMR in food-producing animals; however, this paper adds novelty related to the AMR pathogens in livestock, as we include the recent publications of this field worldwide. In this work, we aim to describe the most critical and high-risk AMR pathogens among food-producing animals, as a worldwide health problem. We also focus on the dissemination of AMR genes in livestock, as well as its consequences in animals and humans, and future strategies to tackle this threat.

Impact of antimicrobial use on abundance of antimicrobial resistance genes in chicken flocks in Vietnam

Objectives

We investigated longitudinally Vietnamese small-scale chicken flocks in order to characterize changes in antimicrobial resistance gene (ARG) content over their life cycle, and the impact of antimicrobial use (AMU) on an intervention consisting of veterinary advice provision.

Methods

AMU data and faecal samples were collected from 83 flocks (25 farms) at day-old, mid- and late-production (∼4 month cycle). Using high-throughput real-time PCR, samples were investigated for 94 ARGs. ARG copies were related to 16S rRNA and ng of DNA (ngDNA). Impact of AMU and ARGs in day-olds was investigated by mixed-effects models.

Results

Flocks received a mean (standard error, SE) animal daily dose (ADD) of 736.7 (83.0) and 52.1 (9.9) kg in early and late production, respectively. Overall, ARGs/16S rRNA increased from day-old (mean 1.47; SE 0.10) to mid-production (1.61; SE 0.16), further decreasing in end-production (1.60; SE 0.1) (all P > 0.05). In mid-production, ARGs/16S rRNA increased for aminoglycosides, phenicols, sulphonamides and tetracyclines, decreasing for polymyxins β-lactams and genes that confer resistance to mutiple classes (multi-drug resistance) (MDR). At end-production, aminoglycoside resistance decreased and polymyxin and quinolone resistance increased (all P < 0.05). Results in relation to ngDNA gave contradictory results. Neither AMU nor ARGs in day-olds had an impact on subsequent ARG abundance. The intervention resulted in 74.2% AMU reduction; its impact on ARGs depended on whether ARGs/ngDNA (+14.8%) or ARGs/16S rRNA metrics (-10.7%) (P > 0.05) were computed.

Conclusions

The flocks' environment (contaminated water, feed and residual contamination) is likely to play a more important role in transmission of ARGs to flocks than previously thought. Results highlight intriguing differences in the quantification of ARGs depending on the metric chosen.

Antibiotic resistance in potential probiotic lactic acid bacteria of fermented foods and human origin from Nigeria

INTRODUCTION

Probiotic lactobacilli are generally recognized as safe (GRAS) and are being used in several food and pharma formulations. However, growing concern of antibiotic resistance in bacterial strains of food origin and its possible transmission via functional foods is increasingly being emphasized.

OBJECTIVES

This study screened potential probiotic lactic acid bacteria (LAB) strains for their phenotypic and genotypic antibiotic resistance profiles.

METHODS

Susceptibility to different antibiotics was assayed by the Kirby Bauer standard disc diffusion protocol. Both conventional and SYBR-RTq-PCR were used for detection of resistance coding genes.

RESULTS

A variable susceptibility pattern was documented against different antibiotic classes. LAB strains irrespective of origin displayed marked phenotypic resistance against cephalosporins, aminoglycosides, quinolones, glycopeptides; and methicillin among beta-lactams with few exceptions. In contrast, high sensitivity was recorded against macrolides, sulphonamides and carbapenems sub-group of beta-lactams with some variations. parC, associated with ciprofloxacin resistance was detected in 76.5% of the strains. Other prevalent resistant determinants observed were aac(6?)Ii (42.1%), ermB, ermC (29.4%), and tetM (20.5%). Six (?17.6%) of the isolates were free from genetic resistance determinants screened in this study.

CONCLUSION

Study revealed presence of antibiotic resistance determinants among lactobacilli from both fermented foods and human sources.

Deciphering risks of resistomes and pathogens in intensive laying hen production chain

Antimicrobial resistance (AMR) and pathogens derived from food animals and their associated environments have emerged as challenging threats to humans from a health perspective, but our understanding of these risks and their key prevention and control points in the current intensive breeding industry remains poor. By creating an integral composition and risk profile of the resistome and microbiome through metagenomics in feces, flies, dust, sewage, and soil along the four-stage laying hen production chain, we found that the whole production chain is a hotspot for antimicrobial resistance genes (ARGs) with 374 known subtypes and pathogens, including 157 human pathogenic bacteria (HPB). Feces and flies were identified as major risk sources for these contaminations. Also, we confirmed a twin-risk of AMR and pathogenicity prevailing throughout the chain, but with different frequencies in each stage; thus, high-risk ARGs in the young chicken stage and highly prioritized HPB in the chick stage contributed 37.33 % to the total AMR risk and 36.36 % to the pathogenic risks, respectively, thus rendering the two stages to be the key prevention points. Moreover, the prevalence of 112 binned ARG supercarriers (for example, Klebsiella pneumoniae harboring 20 ARGs) was unraveled along the production chain, especially in feces, flies, and dust, and 87 potential hosts exhibited high pathogenic risk, high-risk AMR, or both, with 262 ARGs and 816 virulence factor genes. Overall, this study provides first-hand comprehensive data on high-risk ARGs and their pathogenic hosts in the intensive laying hen production chain, and thus is fundamentally important for developing new measures to help control the global AMR crisis induced through the animal-environment-human pathway.

EFSA Panel on Biological Hazards (BIOHAZ), Koutsoumanis K, Allende A, Álvarez‐Ordóñez A, Bolton D, Bover‐Cid S, Chemaly M, Davies R, De Cesare A, Herman L, Hilbert F, Lindqvist R, Nauta M, Ru G, Simmons M, Skandamis P, Suffredini E, Argüello‐Rodríguez H, Dohmen W, Magistrali CF, Padalino B, Tenhagen B, Threlfall J, García‐Fierro R, Guerra B, Liébana E, Stella P, Peixe L. Transmission of antimicrobial resistance (AMR) during animal transport

The transmission of antimicrobial resistance (AMR) between food-producing animals (poultry, cattle and pigs) during short journeys (< 8 h) and long journeys (> 8 h) directed to other farms or to the slaughterhouse lairage (directly or with intermediate stops at assembly centres or control posts, mainly transported by road) was assessed. Among the identified risk factors contributing to the probability of transmission of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs), the ones considered more important are the resistance status (presence of ARB/ARGs) of the animals pre-transport, increased faecal shedding, hygiene of the areas and vehicles, exposure to other animals carrying and/or shedding ARB/ARGs (especially between animals of different AMR loads and/or ARB/ARG types), exposure to contaminated lairage areas and duration of transport. There are nevertheless no data whereby differences between journeys shorter or longer than 8 h can be assessed. Strategies that would reduce the probability of AMR transmission, for all animal categories include minimising the duration of transport, proper cleaning and disinfection, appropriate transport planning, organising the transport in relation to AMR criteria (transport logistics), improving animal health and welfare and/or biosecurity immediately prior to and during transport, ensuring the thermal comfort of the animals and animal segregation. Most of the aforementioned measures have similar validity if applied at lairage, assembly centres and control posts. Data gaps relating to the risk factors and the effectiveness of mitigation measures have been identified, with consequent research needs in both the short and longer term listed. Quantification of the impact of animal transportation compared to the contribution of other stages of the food-production chain, and the interplay of duration with all risk factors on the transmission of ARB/ARGs during transport and journey breaks, were identified as urgent research needs.

Metagenomic analysis reveals the microbiome and antibiotic resistance genes in indigenous Chinese yellow-feathered chickens

Yellow-feathered chickens have great nutritional value and are widely and traditionally used in China, on an industrial scale as broilers. The presence of intestinal microbes has been shown to correlate with poultry performance and serves as an essential reservoir of antibiotic resistance genes (ARGs). Antibiotic resistance is a major public health concern. Here, we investigated functional characteristics of the gut microbiome of indigenous Chinese yellow-feathered chickens (the Huiyang Bearded, Xinghua, Huaixiang, Zhongshan Shanlan, Qingyuan Partridge, and Yangshan chickens) through metagenomic sequencing and reconstructed 409 draft genomes, including 60 novel species and 6 novel genera. Furthermore, we assessed the functions of the intestinal microbial communities and examined the ARGs within them. The results showed that the microbial populations of yellow-feathered broilers were primarily dominated by Bacteroidetes and Firmicutes at the phylum level and Bacteroides at the genus level. Furthermore, the Qingyuan Partridge chicken showed a significantly higher abundance of Prevotella than the other five breeds of chicken. Principal coordinates analysis indicated significant differences in the structures of microbial communities and ARGs, based on the binary Jaccard distance, among the six chicken breeds. Moreover, 989 ARGs conferring tetracycline, multidrug, and aminoglycoside resistance were identified, which represented more than 80% of the faecal resistomes; the most abundant gene in the yellow-feathered chickens was tet(Q). In addition, we found the greatest abundance of resistance genes in Xinghua chickens, indicating that Xinghua chickens are highly resistant to antibiotics. Overall, our findings revealed differences in the gut microbial community structure of indigenous Chinese yellow-feathered broiler breeds and the composition and characteristics of ARGs and antibiotic resistance that enabled us to reconstruct the yellow-feathered chicken gut microbial community genomes. The current data significantly improves our knowledge of the gut microbiome and antibiotic resistance of popular broiler breeds in China.