One-Third of Campylobacter from Poultry, Pork Supply Chains in Northeast India Study Show Multidrug Resistance
A new study examining Campylobacter jejuni contamination along poultry and pig food supply chains in Northeast India found that approximately 31 percent of isolates were multidrug-resistant, while more than half demonstrated biofilm-forming ability. The researchers also reported the first genomic characterization of C. jejuni from porcine sources in India.
The study, published in Applied Food Research, was conducted by researchers from the Indian Council of Agricultural Research (ICAR) and Central Agricultural University. The researchers investigated the occurrence, antimicrobial resistance (AMR), virulence characteristics, and genomic diversity of C. jejuni in poultry and pork supply chains in the Indian state of Meghalaya.
Researchers collected 864 samples from poultry and pig farms, slaughter operations, and retail meat shops, including chicken meat, chicken intestines, pork, pig intestines, and animal swabs. Of these samples, 27 (3.13 percent) tested positive for C. jejuni.
The highest occurrence was observed in chicken intestines (9.72 percent), followed by pork (7.64 percent) and chicken meat (1.39 percent). No C. jejuni was isolated from poultry cloacal swabs, pig intestines, or pig rectal swabs.
Drug Resistance and Biofilm Formation
Antimicrobial susceptibility testing of 26 isolates revealed high resistance to nalidixic acid and tetracycline (73.1 percent each), followed by ampicillin (42.3 percent) and ciprofloxacin (19.2 percent). Resistance to erythromycin and azithromycin was observed in 7.7 percent of isolates each.
Multidrug resistance (i.e., demonstrating resistance to three or more antimicrobial classes) was reported for eight isolates (30.8 percent), including five isolates from pork, two from chicken intestines, and one from chicken meat.
Additionally, 14 isolates (53.9 percent) demonstrated biofilm-forming ability, although all were classified as weak biofilm formers.
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Whole genome sequencing (WGS) of 25 isolates identified several clinically relevant AMR determinants. Notably, 88 percent carried a genomic mutation associated with fluoroquinolone resistance. All sequenced isolates harbored the cmeABC multidrug efflux system, and 44 percent carried conjugative plasmids associated with tetracycline resistance.
Genomic Analysis Reveals Virulence Genes, Genetic Diversity
Genomic analysis also identified virulence genes associated with bacterial adhesion, invasion, toxin production, and immune evasion. Nearly all isolates carried the cdtABC cytolethal distending toxin genes, which contribute to the ability of C. jejuni to cause disease in humans, while 32 percent harbored a combination of genes associated with lipooligosaccharide sialylation, a mechanism implicated in Guillain-Barré syndrome.
Multilocus sequence typing revealed diverse genetic lineages. The researchers also identified sequence types shared across chicken and pork sources.
The researchers emphasized the need for strengthened One Health surveillance and interventions to reduce C. jejuni transmission along food supply chains, particularly in regions where animal intestines and other offal are commonly consumed.
They acknowledged that the study's nonrandom sampling approach, relatively small number of isolates, and limited genomic dataset restricted the generalizability of the findings.
