Backyard chicken flocks have higher rate of Campylobacter than those on farms, study finds

A new prevalence study of the common foodborne bacterium Campylobacter in North Carolina chickens shows it is almost twice as common in backyard flocks than on commercial farms, and isolates are often resistant to antibiotics.

The authors say the findings are significant because chicken is the top consumed meat worldwide, and backyard poultry production is increasing in the United States. The results were published in JAC – Antimicrobial Resistance.

22% samples positive in backyard flocks, 12% on farms

North Carolina State investigators obtained samples from 10 backyard and 10 commercial broiler farms in North Carolina to follow flocks throughout production. They collected fecal and environmental samples at days 10, 31, and 52 days post-hatch in backyard flocks and on days 10, 24, and 38 on commercial farms. Environmental samples were collected from the soil, litter/compost, and feeders and waterers.

Of samples collected from backyard flocks, 21.9% tested positive for Campylobacter, compared with 12.2% of the farm samples. Most of the isolates were identified as C jejuni (70.8%), with the rest C coli (29.2%). The breakdown of positive sample locations in backyard farms was 70.2% from fecal samples, 6.4% from soil, 3.5% from litter/compost, and 19.9% from swabs of feeders and waterers. For commercial farms, the rates were 84.2%, 0%, 12.6%, and 3.2%, respectively.

We found a higher proportion of resistant isolates in commercial farms, with unprecedented higher levels in C. jejuni versus C. coli.

Antimicrobial susceptibility testing revealed phenotypic resistance to ciprofloxacin (40.2%), an important treatment drug for Campylobacter, and tetracycline (46.6%). The researchers found a higher proportion of resistance in C jejuni isolates and on the commercial farms.

The authors concluded, “Despite higher prevalence in backyard farms, we found a higher proportion of resistant isolates in commercial farms, with unprecedented higher levels in C. jejuni versus C. coli.”