In the United States, Campylobacter is the most common bacterial cause of diarrhea, affecting 1.5 million U.S. residents every year.(1) Approximately 30% of Campylobacter strains have decreased susceptibility to fluoroquinolones (e.g., ciprofloxacin) or macrolides (e.g., azithromycin), the antibiotics commonly used to treat infections, which poses a serious threat to public health.(2)
In August 2017, the Florida Department of Health reported six patients diagnosed with Campylobacter jejuni infections, who had exposure to puppies sold by a nationwide pet retailer, primarily based in Ohio. Using PulseNet, the Centers for Disease Control and Prevention (CDC) compared the DNA fingerprints of Campylobacter from the Florida puppies to an infected patient in Ohio, who was a recent customer of the implicated pet retailer. Whole-genome sequencing (WGS) data revealed that the isolates produced by the samples were substantially linked.(3)
In response, the CDC, the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (USDA-APHIS), and several state agencies, investigated a multistate outbreak of multidrug-resistant Campylobacter infections linked to pet store puppies. For this multistate investigation, fecal specimens from puppies were collected at associated pet stores in Kentucky, Ohio, Pennsylvania, and Wisconsin for culture and Whole-genome sequencing, to determine isolate relatedness. Also, the genomes were sequenced for resistance determinants in order to predict antibiotic resistance. Additionally, patients were interviewed regarding demographic characteristics (age, sex, race, ethnicity, and state of residence), health outcomes, and dog exposure during seven days before illness onset (contact with dog or puppy, type of exposure, pet store, or breeder affiliation).(3)
113 people with laboratory-confirmed infections or symptoms consistent with Campylobacter infection were linked to this outbreak. Illnesses were reported from 18 states. 99% of people reported contact with a puppy in the week before the illness started. 29 of the infected persons worked at the pet store chain in question. Outbreak isolates were resistant by antibiotic susceptibility testing to all antibiotics commonly used to treat Campylobacter infections, including macrolides and quinolones. Store records revealed that among 149 investigated puppies, 142 (95%) received one or more courses of antibiotics, raising concern that antibiotic use might have led to the development of resistance in the Campylobacter isolates.
No deaths were reported, although 26 patients were hospitalized. Whole genome sequencing (WGS) showed that isolates from people infected with Campylobacter were closely related genetically. This close genetic relationship means that people in this outbreak were more likely to share a common source of infection. It was concluded that the puppies became infected at the breeders, rather than at the pet stores.
Traceback investigations did not implicate any particular retailer, distributor, transporter, or breeder. Nevertheless, Campylobacter can be part of the normal gut microbiota of many dogs and has zoonotic potential to create illness in humans, while most dogs will be asymptomatic. The two usual culprits are C. jejuni and C. upsaliensis. (5) It’s estimated that 78 million dogs are owned in the United States. Approximately 44% of all households in the United States have a dog.(6) To help prevent the spread of Campylobacter infections, the CDC advises to maintain good hygiene and handling practices after touching a puppy or dog, after handling their food, and after cleaning up after them.(7)