Persistence of antibiotic resistant pathogens and commensal bacteria in “no antibiotic ever” production broiler house litter

Authors: Oladeinde, Adelumola - Ade; Cook, Kimberly - Kim; Strickland, Timothy; ABDO, ZAID - Colorado State University; Plumblee Lawrence, Jodie; Cudnik, Denice; House, Sandra; WOYDA, REED - Colorado State University; Endale, Dinku

Submitted to: World Poultry Congress Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/29/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: We conducted an on-farm longitudinal study to evaluate the occurrence and persistence of pathogens (Salmonella and Campylobacter) and commensal bacteria (E. coli, Staphylococcus and Enterococcus) with antibiotic resistance under a “No Antibiotic Ever (NAE)” production system. The broiler farm was comprised of four broiler houses (> 22, 000 birds/house) and the bedding material used was composed of peanut hull. Broiler litter samples (n =288) were collected at the beginning (7 to 10 days after bird placement) and at the end (4-6 weeks after broiler placement) of each grow-out cycle (49 days), for three consecutive flocks. Pathogens and commensals were quantified, identified and characterized with VITEK® (bioMerieux), whole genome sequencing and antimicrobial susceptibility testing. Additionally, broiler house and litter physico-chemical parameters such as temperature, pH and moisture were monitored throughout the study. Overall, pathogen and commensal populations in litter declined significantly (p< 0.05) from flock 1 to flock 3. Salmonella isolates (n = 47) were grouped into six O serogroups (C2, C3, DI, D2, B and E) and S. Kentucky (~ 56%) and S. Enteritidis (~ 30%) were the top serovars found in litter at the end of the 3rd flock. None of the Salmonella isolates tested carried antibiotic resistance. Campylobacter coli isolates (~ 80%) were resistant to tetracycline and C. jejuni isolates (~ 90% ) were susceptible to all drugs tested. The majority of the E. coli isolates (~ 62.5%) were resistant to at least one class of antibiotics and multidrug resistant (resistance to two or more classes of antibiotics) E. coli persisted from flock to flock. The major Enterococcus spp identified were E. hirae (~ 65%) and E. faecalis (~ 15%), and these isolates harbored resistance to at least one class of antibiotics. Staphylococcus isolates (~ 45%) displayed resistance to lincomycin, and S. cohnii subsp. urealyticus (~ 27%) and S. xylosus (~15%) were the representative species present in litter from flock to flock. The temperature of the broiler house was the most important parameter that could explain the variability in our data. Our results suggest that the reuse of the same litter over the grow-out of multiple flocks under “NAE” production resulted in a reduction of Salmonella and Campylobacter population in litter, however, multidrug resistant commensal bacteria persisted from flock to flock.