Seasonal dynamics, antimicrobial resistance, and genetic lineages of thermotolerant Campylobacter isolates from South American camelids

Background

South American camelids (SACs) are increasingly kept as companion animals, but their role in zoonotic transmission is poorly understood. Thermotolerant Campylobacter spp. are a leading cause of bacterial zoonoses globally. This study investigated the occurrence and zoonotic potential of thermotolerant Campylobacter spp. in SACs on German farms.

Methods

Fecal swabs from up to 20 animals on 10 farms were collected across four seasons. Campylobacter spp. were isolated, and genomes were typed to assess multilocus sequence types (STs), virulence, and antimicrobial resistance.

Results

Campylobacter spp. were detected in 23/717 samples (3.2 %), including 16 Campylobacter jejuni from seven farms and seven Campylobacter coli from two farms. Detection was higher in alpacas (4.9 %, 21/427) than in llamas (0.7 %, 2/288), with higher rates in summer. Molecular typing revealed high genetic heterogeneity, though some STs recurred across timepoints, animals, and farms, suggesting potential endemic colonization. Nine distinct C. jejuni STs and two C. coli STs were identified, many belonging to clonal complexes (CCs) common in livestock and humans. All isolates carried virulence-associated genes for motility, adhesion, invasion, and toxin production, while several from CC21 harbored genes linked to Guillain-Barré syndrome. Antimicrobial susceptibility testing showed wild-type phenotypes for erythromycin, gentamicin, and chloramphenicol. Ciprofloxacin resistance, with T86I mutation in gyrA, was found in three isolates; one C. jejuni isolate carried tet(O) conferring tetracycline resistance.

Conclusion

SACs harbor Campylobacter strains related to human and livestock lineages, with virulence and resistance traits relevant for zoonotic transmission. Their presence on German farms highlights the need targeted surveillance and biosecurity within a One Health framework.