Impact of different management measures on the colonization of broiler chickens with ESBL- and pAmpC- producing Escherichia coli in an experimental seeder-bird model

Abstract

The colonization of broilers with extended-spectrum β-lactamase- (ESBL-) and plasmid-mediated AmpC β-lactamase- (pAmpC-) producing Enterobacteriaceae has been extensively studied. However, only limited data on intervention strategies to reduce the colonization throughout the fattening period are available. To investigate practically relevant management measures for their potential to reduce colonization, a recently published seeder-bird colonization model was used. Groups of 90 broilers (breed Ross 308) were housed in pens under conventional conditions (stocking of 39 kg/m2, no enrichment, water and feed ad libitum). Tested measures were investigated in separate trials and included (I) an increased amount of litter in the pen, (II) the reduction of stocking density to 25 kg/m2, and (III) the use of an alternative broiler breed (Rowan x Ranger). One-fifth of ESBL- and pAmpC- negative broilers (n = 18) per group were orally co-inoculated with two E. coli strains on the third day of the trial (seeder). One CTX-M-15-positive E. coli strain (ST410) and one CMY-2 and mcr-1-positive E. coli strain (ST10) were simultaneously administered in a dosage of 102 cfu. Colonization of all seeders and 28 non-inoculated broilers (sentinel) was assessed via cloacal swabs during the trials and a final necropsy at a target weight of two kilograms (= d 36 (control, I-II), d 47 (III)). None of the applied intervention measures reduced the colonization of the broilers with both the ESBL- and the pAmpC- producing E. coli strains. A strain-dependent reduction of colonization for the ESBL- producing E. coli strain of ST410 by 2 log units was apparent by the reduction of stocking density to 25 kg/m2. Consequently, the tested management measures had a negligible effect on the ESBL- and pAmpC- colonization of broilers. Therefore, intervention strategies should focus on the prevention of ESBL- and pAmpC- colonization, rather than an attempt to reduce an already existing colonization.

Impact of On-Farm Interventions against CTX-Resistant Escherichia coli on the Contamination of Carcasses before and during an Experimental Slaughter

“…The feathers of the chickens appeared less dirty and wet in the 25 kg/sqm group as compared to the other groups. In addition to the overall external contamination, one can assume that the reduced stocking density might have an impact on the colonization and the spread of the resistant bacteria between the chickens during the fattening period, as indicated previously [23].…”

“…Two different CTX-resistant E. coli strains were used for the infection trials [23]. Strain 10716 harbors a bla CTX-M-15 and is assigned as MLST ST-410 whereas strain 10717 harbors the bla genes for a TEM-1 beta-lactamase and a CMY-2 plasmid-encoded cephalosporinase (pAmpC beta-lactamase) and is assigned as MLST ST-10.…”

“…One control group (CG) and four intervention groups were investigated in this study: drinking water supplement (DW), slow growing breed Rowan × Ranger (RR), reduced stocking density (25 kg/sqm) and competitive exclusion (CE). These intervention measures were applied throughout the fattening period as previously described [23]. In brief, the DW group received a water a supplement based on a mixture of organic acids widely used in broiler production added to the drinking water three times during the rearing cycle as recommended by the manufacturer (fattening days 2-7, days 15-19, days 31-38).…”

Modeling the Impact of Management Changes on the Infection Dynamics of Extended-Spectrum Beta-Lactamase-Producing Escherichia coli in the Broiler Production

“…Due to the high prevalence of ESBL in broiler farms in Europe [ 10 , 15 ] and in fresh retail chicken meat [ 16 , 17 ], it is necessary to investigate measures against ESBL-producing E. coli along the entire poultry production chain. Starting from the hatchery [ 18 , 19 , 20 ], the fattening farm [ 21 , 22 , 23 , 24 , 25 ], the slaughterhouse [ 26 , 27 , 28 , 29 ] and even the manure applied as fertilizer to agricultural land [ 30 , 31 ], studies have been conducted.…”

“…They found studies showing a small effect (“feed additives”) and others with a potentially strong impact (“cleaning and disinfection” and “competitive exclusion”) on the incidence of ESBL/AmpC-producing E. coli in poultry. Robé et al [ 21 ] investigated the measures “increased amount of litter in the pen”, “reduced stocking density” and “the use of an alternative broiler breed” in an experimental setting. They measured negligible effects on the magnitude of colonization of the broilers with both strains, the ESBL and the pAmpC-producing E. coli to which the birds were exposed.…”