Emerging Antimicrobial Resistance in Poultry: What Practicing Veterinarians Need to Know

Antimicrobial resistance (AMR) has become an increasing concern in poultry production, where antibiotics are widely used to manage bacterial diseases and maintain flock health. While these drugs remain essential for treating infections, their extensive use has contributed to the emergence of resistant bacterial pathogens. For practicing poultry veterinarians, understanding resistance trends and transmission pathways is essential for making informed clinical and flock health decisions. 

Antibiotic Use and the Development of Resistance 

Antibiotics such as tetracyclines, macrolides, aminoglycosides, beta-lactams, and fluoroquinolones are commonly used to treat bacterial diseases in poultry, including respiratory infections caused by Mycoplasma gallisepticum, enteric diseases such as necrotic enteritis caused by Clostridium perfringens, and septicemic infections associated with Escherichia coli¹. 

However, frequent antimicrobial exposure creates selective pressure that allows resistant bacteria to survive and multiply. The use of antibiotics for disease prevention, administration through feed or water, and easy over-the-counter availability in some settings further contribute to the emergence and persistence of antimicrobial resistance. Continuous exposure to low concentrations of antibiotics particularly favors the selection of resistant bacterial populations². 

Resistant Pathogens Affecting Poultry Health 

Several bacterial pathogens of veterinary importance have developed resistance to commonly used antibiotics, making disease management increasingly challenging. 

Among the most significant are: 

• ESBL-producing Escherichia coli, which exhibit resistance to extended-spectrum cephalosporins³. 

• Salmonella enterica, with reported resistance to ampicillin, tetracycline, and nalidixic acid². 

• Campylobacter jejuni, which is increasingly demonstrating resistance to erythromycin and fluoroquinolones². 

The emergence of these resistant pathogens can reduce treatment effectiveness and complicate infection control within poultry production systems. 

Transmission Beyond the Poultry House 

Resistant bacteria are not confined to infected flocks and can spread through multiple pathways. 

Foodborne transmission remains a major concern. Improper handling of poultry meat, consumption of undercooked products, and cross-contamination during processing or food preparation can facilitate the movement of resistant bacteria beyond poultry production systems^2,4. 

Environmental dissemination also contributes to the persistence of resistance. Poultry litter used as fertilizer may contain antibiotic residues, resistant bacteria, and antimicrobial resistance genes. Runoff and groundwater contamination allow resistance genes, including bla_CTX-M and tetA, to persist in the environment and spread among bacterial populations^2,5. 

Cross-species transmission further complicates the situation. Companion animals may acquire resistant bacteria through exposure to poultry litter or raw poultry products, while shared environments can facilitate the movement of resistance genes between bacterial populations. Plasmids carrying resistance to fluoroquinolones, aminoglycosides, and ESBLs have been identified in Escherichia coli isolated from both poultry and dogs, demonstrating the mobility of antimicrobial resistance determinants^6,7,8. 

Conclusion 

Antimicrobial resistance in poultry extends beyond reduced treatment efficacy and has implications for flock health, food safety, and the wider animal production environment. Awareness of common resistant pathogens, responsible antimicrobial use, and the multiple pathways through which resistance can spread enables veterinarians to make informed clinical decisions while supporting sustainable poultry health management. Continuous attention to antimicrobial stewardship and effective disease prevention remains essential for limiting the emergence and dissemination of resistant bacteria in poultry production. 

References 

1. Sari DA. Antimicrobial Resistance in Companion Animals: A Growing One Health Concern. Veterinary & Life Science Innovations. 2025 Mar 6;2(1):1-9. https://velsi.id/index.php/velsi/article/download/10/8 

2. Naheed G, Sultan T, Barvi LA. Emerging antimicrobial resistance in companion, farm animals and poultry: a veterinary concern. Journal of Medical & Health Sciences Review. 2025 Jun 6;2(2). https://jmhsr.info/index.php/jmhsr/article/download/346/438 

3. NWANKWO IO, ATANU SJ, EZENDUKA EV, AGADA GO. Prevalence and risk of antibiotic-resistant E. coli and strain O157: H7 spread in waste water, chicken, and handlers: A case study. Notulae Scientia Biologicae. 2025 Mar 27;17(1):12242-. https://notulaebiologicae.ro/index.php/nsb/article/download/12242/9770 

4. Ferraz MP. Antimicrobial resistance: the impact from and on society according to one health approach. Societies. 2024 Sep 17;14(9):187. https://www.mdpi.com/2075-4698/14/9/187 

5. Diarra B, Guindo I, Koné B, Dembélé M, Cissé I, Thiam S, Konaté K, Tékété M, Maīga A, Maīga O, Timbiné L. High frequency of antimicrobial resistance in Salmonella and Escherichia coli causing diarrheal diseases at the Yirimadio community health facility, Mali. BMC microbiology. 2024 Jan 23;24(1):35. https://link.springer.com/content/pdf/10.1186/s12866-024-03198-4.pdf 

6. Tokuda M, Shintani M. Microbial evolution through horizontal gene transfer by mobile genetic elements. Microbial Biotechnology. 2024 Jan;17(1):e14408. https://enviromicro-journals.onlinelibrary.wiley.com/doi/pdfdirect/10.1111/1751-7915.14408?utm_source=consensus 

7. Nocera FP, De Martino L. Methicillin-resistant Staphylococcus pseudintermedius: epidemiological changes, antibiotic resistance, and alternative therapeutic strategies. Veterinary Research Communications. 2024 Dec;48(6):3505-15. https://link.springer.com/content/pdf/10.1007/s11259-024-10508-8.pdf 

8. Marco-Fuertes A, Marin C, Gimeno-Cardona C, Artal-Muñoz V, Vega S, Montoro-Dasi L. Multidrug-resistant commensal and infection-causing Staphylococcus spp. isolated from companion animals in the Valencia region. Veterinary Sciences. 2024 Jan 26;11(2):54. https://www.mdpi.com/2306-7381/11/2/54