Review of antibiotic use and resistance in food animal production in WHO South-East Asia Region

Enhanced Detection of Enrofloxacin in Seawater Using a Newly Selected Aptamer on a Graphite Oxide-Based Biosensor

Developing aptasensors offers several advantages including sensitivity, selectivity, cost-effectiveness, and speed over traditional analytical techniques for antibiotic detection. We have successfully identified Enro_ap3, a 30-mer enrofloxacin-binding aptamer with micromolar binding affinity, through an optimized Capture-SELEX platform. Compared to other reported enrofloxacin-binding aptamers, this shorter aptamer not only streamlines the design process but also eliminates the common issue of strong nonspecific binding to the GO surface, thereby improving the overall detection capabilities of the biosensor (GO-Enro_ap3-FAM). This GO aptasensor demonstrated remarkable selectivity by effectively distinguishing enrofloxacin from different structurally diverse antibiotics. The sensor boasts a LOD of 32.15 μg/mL, 2.5 times more sensitive than the original 30-mer, with recoveries of 74%-92% and relative standard deviations of 6.3%-12.5% in seawater samples spiked with enrofloxacin. Furthermore, the GO aptasensor's detection capabilities were found to be on par with traditional LC-MS/MS techniques, exhibiting no significant differences in recovery rates even in complex matrices. The sensor's performance remained consistent across variations in salinity, acidity, and total organic carbon concentrations in seawater samples collected from different locations, underlining its robustness in diverse environmental conditions and its suitability for real-world seawater monitoring applications. Our findings highlight the importance of the aptamer's chain length and its binding affinity toward the target after immobilization on the GO substrate. These factors significantly impact the performance of GO aptasensors in seawater. Overall, the GO aptasensor provides a well-balanced approach, combining sensitivity, environmental adaptability, and practical usability for detecting pharmaceutical contaminants, such as antibiotics, in marine environments.

Prevalence and molecular epidemiology of methicillin-resistant Staphylococcus aureus in livestock farmers, livestock, and livestock products in southern Sri Lanka: A one health approach

Methicillin-resistant Staphylococcus aureus (MRSA) colonization can lead to subsequent severe infections. Unlike community and hospital-associated types, Livestock-associated MRSA (LA-MRSA) transmits to humans through direct contact with livestock and contaminated livestock products. This study aimed to investigate MRSA prevalence and molecular epidemiology in livestock farmers, livestock, and livestock products, including LA-MRSA presence and MRSA abundance in human and animal nasal microbiome, in southern Sri Lanka using a One Health approach. Nasal swabs from farmers and livestock on 50 farms (Nov 2020 - Dec 2021) and livestock products were collected. MRSA was isolated and confirmed using standard microbiological techniques. Staphylococcal chromosomal cassette mec typing, spa typing, and multilocus sequence typing were performed. Identified clones were compared with hospital isolates. Metagenomics analysis was performed on selected samples. MRSA prevalence was 24.0 % (12/50) in farms, 7.9 % (12/152) in farmers, 2.1 % (5/240) in livestock, and 1.9 % (3/157) in products. Of 372 S. aureus collected from clinical cultures, 59.4 % were MRSA. MRSA clones were identified in farm personnel (CC5/ST5/t002, CC1/ST1/t127, and ST45/CC45/t026), livestock (CC5/ST5/t002), and clinical cultures (CC5/ST5/t002 and CC5/ST6/t304), with ST45/CC45/t026 and CC5/ST6/t304 reported for the first time in Sri Lanka. LA-MRSA clones (ST389/ST9) were not detected. Animals had more diverse nasal microbiomes and lower MRSA abundance (<1.4 %) compared to humans (>82.3 %). MRSA colonization prevalence in southern Sri Lanka was relatively low. Two new clones and no LA-MRSA clones were identified. This study highlights the importance of continuing MRSA surveillance under the One Health framework to identify MRSA transmission between humans, animals, and the environment.

Antibiotic residues in poultry products and bacterial resistance: A review in developing countries

Antimicrobial resistance (AMR) is a growing global concern, particularly in poultry farming, where antibiotics are widely used for both disease prevention and growth promotion. This review examines the misuse of antibiotics in poultry production, especially in developing countries, and its contribution to the emergence of antibiotic-resistant bacteria. The findings highlight that factors such as increasing demand for poultry protein, the availability of inexpensive antibiotics, and weak regulatory oversight have led to widespread misuse, accelerating the spread of resistance genes. Although evidence links poultry farming to AMR, significant data gaps remain, especially regarding resistance transmission from poultry to humans. The review underscores the urgent need for stronger regulatory frameworks, phased-out use of antimicrobial growth promoters, and enhanced awareness campaigns to address this issue. Improving the capacity of regulatory bodies and developing more robust national data monitoring systems are essential steps to mitigate the threat of AMR in poultry farming and to protect both animal and human health.

Assessing the pig microbial health impacts of smallholder farming

The livestock industry has long been a hotspot environment for antibiotic resistance genes, with smallholder farming still holding a significant position in pig farming. However, the microbial antibiotic resistance and pathogen risks in pigs under the smallholder farming model remain unclear. We systematically analyzed the antibiotic resistance and microbial composition of pig feces from smallholder and large-scale farming models in Sichuan. The results indicated a lower abundance of antibiotic resistance genes (ARGs) and similar microbial composition in smallholder farming compared to large-scale farming. Beneficial bacteria were more abundant in small-scale farming, whereas large-scale farming exhibited more ARGs, virulence genes, and human pathogenic bacteria (HPBs), including ESBL Escherichia coli strains closely related to human strains, indicating higher zoonotic risk. The findings suggest that smallholder farming presents a relatively better microbial composition and resistance profile, highlighting its advantages over large-scale farming in terms of pig and human health. It is noteworthy that a considerable proportion of HPBs carrying ARGs still exist in the feces from smallholder farming, and given the openness of fecal handling, there remains a high risk of transmitting ARGs and pathogens to humans.

Diet-induced changes in the jejunal microbiota of developing broilers reduce the abundance of Enterococcus hirae and Enterococcus faecium

Modern broiler breeds allow for high feed efficiency and rapid growth, which come at a cost of increased susceptibility to pathogens and disease. Broiler growth rate, feed efficiency, and health are affected by the composition of the gut microbiota, which in turn is influenced by diet. In this study, we therefore assessed how diet composition can affect the broiler jejunal gut microbiota. A total of 96 broiler chickens were divided into four diet groups: control, coated butyrate supplementation, medium-chain fatty acid supplementation, or a high-fibre low-protein content. Diet groups were sub-divided into age groups (4, 12 and 33 days of age) resulting in groups of 8 broilers per diet per age. The jejunum content was used for metagenomic shotgun sequencing to determine the microbiota taxonomic composition at species level. The composed diets resulted in a total of 104 differentially abundant bacterial species. Most notably were the butyrate-induced changes in the jejunal microbiota of broilers 4 days post-hatch, resulting in the reduced relative abundance of mainly Enterococcus faecium (-1.8 l2fc, Padj = 9.9E-05) and the opportunistic pathogen Enterococcus hirae (-2.9 l2fc, Padj = 2.7E-08), when compared to the control diet. This effect takes place during early broiler development, which is critical for broiler health, thus exemplifying the importance of how diet can influence the microbiota composition in relation to broiler health. Future studies should therefore elucidate how diet can be used to promote a beneficial microbiota in the early stages of broiler development.

Knowledge and practices related to antibiotics among poultry producers and veterinarians in two Indian states

Background

Antibiotics are frequently utilized in livestock, particularly poultry, for therapy and growth promotion, resulting in antimicrobial resistance. Multidrug-resistant bacteria are frequent in poultry samples from India. The purpose of this study was to better understand main antibiotic consumption patterns in poultry value chains, as well as antibiotic knowledge and practices among the stakeholders.

Methods

A cross-sectional survey was conducted in Assam and Karnataka, India. The poultry farmers were interviewed on antibiotic usage, antibiotic knowledge, feeding practices, and preventive measures on the farm. Poultry farmers reported their veterinarians, and we also interviewed them on knowledge and practices related to antimicrobial use in poultry and antimicrobial resistance. Item response theory (IRT) was used to assess the association between the answers and demographic factors.

Results

This survey interviewed 62 poultry farmers and 11 veterinarians. Small poultry farms with fewer than 4000 birds were owned by 51.6% of farmers. Most poultry farmers had heard about antibiotics, and 62.9% thought they cured all diseases. If one chicken is sick, 72.6% said others should be given antibiotics to prevent the disease. All veterinarians utilized tetracyclines, aminoglycosides, and cephalexin on the poultry farms. Over half (54.5%) stated antibiotics prevent diseases, and 72.7% said they treat and prevent diseases. Some (45.5%) said antibiotics boost growth. IRT analysis showed that 8 questions assessed a knowledge scale well. Univariable analysis showed that Assam farmers and women were likely to have have more knowledge.

Conclusion

The poultry farmers were mostly unaware of the relation between antibiotic use and antimicrobial resistance. Despite being aware, the veterinarians agreed with use antibiotics as a prophylactic measure. It is vital that these stakeholders understand the repercussions of such widespread antibiotic use. In order to increase knowledge, frequent trainings and antimicrobial stewardship programmes with effective communication and incentives for behaviour change should be conducted.

Unveiling the landscape of resistance against high priority critically important antimicrobials in food-producing animals across Africa: A scoping review

The rapid population growth in Africa is associated with an increasing demand for livestock products which in turn can lead to antimicrobial use. Antimicrobial usage in animals contributes to the emergence and selection of resistant bacteria which constitutes a serious public health threat. This study aims to review and summarize the available information on highest priority critically important antimicrobials (HPCIAs) resistance in livestock production in Africa. This work will help to inform future policies for controlling antimicrobial resistance (AMR) in the food production chain. A scoping review was conducted according to the Cochrane handbook and following PRISMA 2020 guidelines for reporting. Primary research studies published after 1999 and reporting resistance of Escherichia coli, Enterococcus spp, Staphylococcus aureus, Salmonella spp, and Campylobacter spp to HPCIAs in poultry, cattle, pigs, goats, and sheep in Africa were searched in four databases. A total of 312 articles were included in the review. The majority of the studies (40.7) were conducted in North African countries. More than 49.0% of included studies involved poultry and 26.2% cattle. Cephalosporins and quinolones were the most studied antimicrobial classes. Of the bacteria investigated in the current review, E. coli (41.7%) and Salmonella spp (24.9%) represented the most commonly studied. High levels of resistance against erythromycin in E. coli were found in poultry (MR 96.1%, IQR 83.3-100.0%), cattle (MR 85.7%, IQR 69.2-100.0%), and pigs (MR 94.0%, IQR 86.2-94.0%). In sheep, a high level of resistance was observed in E. coli against nalidixic acid (MR 87.5%, IQR 81.3-93.8%). In goats, the low level of sensibility was noted in S. aureus against streptomycin (MR 86.8%, IQR 19.4-99.0%). The study provides valuable information on HPCIAs resistance in livestock production in Africa and highlights the need for further research and policies to address the public health risk of AMR. This will likely require an investment in diagnostic infrastructure across the continent. Awareness on the harmful impact of AMR in African countries is a requirement to produce more effective and sustainable measures to curb AMR.