Role of darkling beetles (Alphitobius diaperinus) and litter in spreading and maintaining Salmonella Enteritidis and Campylobacter jejuni in chicken flocks

Authors: BARUA, SUBARNA - Auburn University; BAILEY, MATTHEW - Auburn University; ZHONG, KEVIN - Auburn University; IDUU, NNEKS - Auburn University; DORMITORIO, TERESA - Auburn University; MACKLIN, KENNETH - Auburn University; BOURASSA, DIANNA - Auburn University; PRICE, STUART - Auburn University; HAUCK, RUEDIGER - Auburn University; KREHLING, JAMES - Auburn University; KITCHENS, STEVE - Auburn University; KYRIAKIS, CONSTANTIONS - Auburn University; Buhr, Richard - Jeff; WANG, CHENGMING - Auburn University

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: Salmonella and Campylobacter are common human foodborne pathogens found in broiler chickens, but their persistence mechanisms within flocks are not fully understood. In this study, four groups of chicks (n=50) were orally inoculated with either 100,000,000 Salmonella or Campylobacter bacterial cells, housed inside containers with wood shavings as litter and beetles (n=200). Phase-I (weeks 1-3): the infected chicks remained in the containers and were then euthanized, but the beetles and litter remained in the container (group-A), beetles were removed and litter remained in the container (group-B), beetles remained and litter was removed (group-C), and beetles and litter were removed (group-D). Phase II (weeks 5-7): new litter was added to containers in groups C and D, and new chicks (n=50) were introduced to all groups. Phase III (weeks 8-20): all chicks were euthanized, and the litter and/or beetles remained in the containers for 17 weeks. The prevalence of Salmonella and Campylobacter was significantly higher (10 to 40%) when detected using molecular (DNA) techniques compared to traditional culture. In phase II, when infected chicks were removed and new chicks were introduced, one fecal sample in group B and three litter samples in groups B and C were found positive for Salmonella, and Campylobacter was still detected in groups A, B, and C litter samples, but not in beetles. In phase III, when all chicks were removed, Salmonella was identified in beetle samples from group A and the litter samples of all tested groups A, B, and C, and C. jejuni was positive in litter samples from groups A and B but not in the beetle. Sixty-nine days after removing infected chicks, culturable Salmonella was still recovered from the beetles. Salmonella and Campylobacter were detectable in litter up to 127 days after removing infected chicks. This study highlights the potential for transmission of Salmonella and Campylobacter via beetles and litter to new flocks of chicks in successive rearing cycles. Intensive control programs should target beetle exclusion and implement strict poultry litter treatment and management between flocks to reduce Salmonella, Campylobacter, and beetles.

Technical Abstract: Salmonella and Campylobacter are common foodborne pathogens in chickens, but their persistence mechanisms within flocks are not fully understood. In this study, four groups of SPF Leghorn chickens (n=50) were orally inoculated with 10^8 Salmonella Enteritidis and 10^8 Campylobacter jejuni, housed in BSL-2 rooms inside containers with autoclaved bedding and beetles (n=200). Phase-I (weeks 1-3): the infected chickens remained in the containers and were then euthanized while beetles and litter remained in the container (group-A), beetles were removed and litter remained in the container (group-B), beetles remained and litter was removed (group-C), and beetles and litter were removed (group-D). Phase II (weeks 5-7): autoclaved bedding was added to containers in groups C and D, and new SPF chickens (n=50) were introduced and kept. Phase III (weeks 8-20): all chickens were euthanized, and the litter and/or beetles remained in the containers for 17 weeks. The prevalence of Salmonella Enteritidis and Campylobacter was significantly higher when detected by PCR compared to culture. In phase II, when infected chickens were removed and new chickens were introduced, one fecal sample in group B and three litter samples in groups B and C were found positive for Salmonella Enteritidis, and Campylobacter was still detected in groups A, B, and C litter samples, but not in beetles. In phase III, when all chickens were removed, Salmonella Enteritidis was identified in beetle samples from group A and the litter samples of all tested groups A, B, and C, and C. jejuni was positive in litter samples from groups A and B but not in the beetle. Sixty-nine days after removing infected chickens, culturable Salmonella was still found in beetles. Salmonella and Campylobacter were detectable in litter up to 127 days after removing infected chickens. This study highlights the transmission of Salmonella and Campylobacter via beetles and litter to new flocks in successive rearing cycles. Intensive control programs should target insect exclusion and implement strict poultry litter management or litter changes between flocks.