Stool specimens from infected persons or Campylobacter isolates were submitted to state public health laboratories. Health and agriculture officials from six states (Florida, Kansas, Kentucky, Ohio, Pennsylvania, and Wisconsin) visited 29 pet stores (27 company A and two company B) to collect puppy fecal samples. All company A and B stores in Ohio were visited, and a convenience sample of stores in other states was selected. Some states also requested fecal samples from patient households that had purchased puppies. Human stool specimens and puppy fecal samples underwent Campylobacter culture, and whole-genome multilocus sequence typing (wgMLST) was performed to compare genetic relatedness. Antibiotic susceptibility testing for nine antibiotics was performed by broth microdilution (Sensititer, Thermo Fisher Scientific) on selected isolates and interpreted using epidemiologic cutoff values established by the European Committee on Antimicrobial Susceptibility Testing. In this report, "resistant" refers to isolates with non–wild-type results. To explore pet food as a possible source of Campylobacter infection in puppies, dog food samples from company A and one person's home were collected for culture.
Campylobacter jejuni isolates were obtained for 51 persons and 23 puppies. Outbreak isolates from 45 persons and 11 puppies grouped into three distinct clades by wgMLST. Six persons whose illnesses did not meet the case definition because their isolates were unrelated by wgMLST were excluded. Twelve puppy isolates were also unrelated to the outbreak by wgMLST. Two clades contained isolates from persons and puppies that were genetically related (≤32 alleles difference within each clade). The third clade contained six patient isolates that were related (≤30 alleles difference). Eighteen outbreak isolates (10 human and eight puppy) representing all three clades were selected for antibiotic susceptibility testing, and all were resistant to azithromycin, ciprofloxacin, clindamycin, erythromycin, nalidixic acid, telithromycin, and tetracycline. In addition, 16 of 18 isolates were resistant to gentamicin, and four of 18 were resistant to florfenicol. None of the cultures of 12 dog food samples yielded Campylobacter.
Morbidity and Mortality Weekly Report. 2018;67(37):1032-1035. © 2018 Centers for Disease Control and Prevention (CDC)