Fluoroquinolone Resistance in Campylobacter: A Growing Veterinary and Public Health Challenge

Fluoroquinolones (FQs), such as ciprofloxacin, are critical antimicrobials used in both human and veterinary medicine. However, resistance in Campylobacter has risen sharply worldwide, posing a major therapeutic challenge^1,2,3. Due to this, FQ-resistant Campylobacter has been classified as a high-priority pathogen by global health agencies⁴. 

Mechanisms Behind Resistance 

Resistance in Campylobacter develops rapidly due to: 

• Mutations in DNA gyrase  

• Strong selection pressure during antibiotic exposure  

These mutations occur readily and are quickly enriched during treatment, both in laboratory and clinical settings¹. 

Veterinary Use and Unintended Consequences 

In veterinary medicine, FQs are widely used to treat infections such as respiratory diseases in poultry, cattle, and swine^1,5. Importantly, they are not used to treat Campylobacter itself. 

However, their use creates unintended consequences: 

• Selection of resistant Campylobacter strains in animal hosts  

• Amplification of resistant populations in livestock  

This is particularly significant in poultry, where Campylobacter prevalence is high, and antibiotic exposure can rapidly select resistant strains¹. 

Transmission to Humans 

Resistant strains developed in animals can be transmitted to humans through: 

• Contaminated meat products  

• Environmental pathways  

Epidemiological data have shown a clear link between FQ use in food animals and increased resistance in human infections¹. 

Regulatory and Field Observations 

Due to rising concerns, regulatory actions have been taken. For instance, the U.S. FDA withdrew approval for FQ use in poultry in 2005¹. 

Comparative studies further highlight: 

• Higher resistance rates in conventional farming systems  

• Lower prevalence in organic systems 

This reinforces the role of antibiotic usage patterns in resistance development. 

Beyond Antibiotic Use: Clonal Expansion 

Interestingly, resistance can emerge even in the absence of direct antibiotic use. Studies from Australia and New Zealand have documented the rise of FQ-resistant Campylobacter despite restrictions on FQ use in poultry¹. 

This suggests: 

• Introduction from external sources (e.g., wildlife)  

• Rapid spread through clonal expansion  

Such findings emphasize that AMR control requires more than just reducing antibiotic use. 

Ruminants and Emerging Risks 

Recent studies have identified high levels of FQ-resistant Campylobacter in cattle and sheep, sometimes without direct antibiotic selection pressure¹. 

Possible contributing factors include: 

• Introduction of resistant strains from wildlife  

• Adaptation and expansion within host populations  

These reservoirs are increasingly recognized as important sources of human infection. 

Practical Implications for Veterinarians 

Veterinarians must adopt a proactive approach: 

• Rational use of fluoroquinolones  

• Monitoring resistance patterns in livestock  

• Strengthening farm biosecurity  

• Recognizing environmental and wildlife interfaces  

Conclusion 

FQ-resistant Campylobacter highlights the complexity of AMR within a One Health framework. While antibiotic use plays a significant role, factors such as environmental transmission and clonal expansion also drive its spread. For veterinarians, addressing this challenge requires a combination of clinical prudence, epidemiological awareness, and integrated One Health strategies. 

References 

1. Zhang Q, Beyi AF, Yin Y. Zoonotic and antibiotic-resistant Campylobacter: A view through the One Health lens. One Health Advances. 2023 Mar 30;1(1):4. https://link.springer.com/content/pdf/10.1186/s44280-023-00003-1.pdf 

2. Qin X, Wang X, Shen Z. The rise of antibiotic resistance in Campylobacter. Current Opinion in Gastroenterology. 2023 Jan 1;39(1):9-15. https://doi.org/10.1097/MOG.0000000000000901 

3. Tang Y, Fang L, Xu C, Zhang Q. Antibiotic resistance trends and mechanisms in the foodborne pathogen, Campylobacter. Animal health research reviews. 2017 Dec;18(2):87-98. https://scholar.archive.org/work/jn3h7wjdh5gbpcpoiryop6nque/access/wayback/https://www.cambridge.org/core/services/aop-cambridge-core/content/view/3CA9C0DA6FA8AE1F0EE12AB80D372380/S1466252317000135a.pdf/div-class-title-antibiotic-resistance-trends-and-mechanisms-in-the-foodborne-pathogen-span-class-italic-campylobacter-span-div.pdf 

4. Tacconelli E, Carrara E, Savoldi A, Harbarth S, Mendelson M, Monnet DL, Pulcini C, Kahlmeter G, Kluytmans J, Carmeli Y, Ouellette M. Discovery, research, and development of new antibiotics: the WHO priority list of antibiotic-resistant bacteria and tuberculosis. The Lancet infectious diseases. 2018 Mar 1;18(3):318-27. https://repository.ubn.ru.nl/bitstream/handle/2066/198275/198275.pdf?sequence=1 

5. Roth N, Käsbohrer A, Mayrhofer S, Zitz U, Hofacre C, Domig KJ. The application of antibiotics in broiler production and the resulting antibiotic resistance in Escherichia coli: A global overview. Poultry science. 2019 Apr 1;98(4):1791-804. https://www.sciencedirect.com/science/article/pii/S0032579119301099