Publication Database

Management measures to reduce the prevalence of broiler chickens with ESBL-/pAmpC- producing enterobacteria (2022)

Art

Hochschulschrift

Autor

Robé, Caroline (WE 10)

Quelle

Berlin, 2022 — VI, 95 Seiten

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/33817

Kontakt

Institut für Tier- und Umwelthygiene

Robert-von-Ostertag-Str. 7-13
14169 Berlin
+49 30 838 51845
tierhygiene@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Extended-spectrum beta-lactamase (ESBL) and plasmid-mediated AmpC beta-lactamase (pAmpC) producing bacteria are frequently detected in the broiler production chain. Investigations revealed a high prevalence of ESBL- and pAmpC- producing bacteria throughout the broiler fattening process up to the slaughterhouse level and consumer goods and revealed several transmission routes of these antibiotic-resistant bacteria. Insights into the colonization dynamics of broiler chickens and possible intervention measures are needed as the transmission of ESBL- and pAmpC- producing bacteria to humans via close contact with livestock or the consumption of contaminated meat is assumed. This thesis aimed to determine the minimal bacterial count necessary to colonize broiler chickens with ESBL- and pAmpC- producing Escherichia coli (E. coli) and to establish a broiler chicken colonization model (seeder-bird) close to real farming conditions without applying any antimicrobial selection pressure. Subsequently, we aimed to evaluate distinct intervention measures on their potential to reduce the colonization of broiler chickens with ESBL- and pAmpC- producing E. coli throughout the fattening process. For the determination of the minimal bacterial count, ESBL- and pAmpC- negative day-old broiler chickens (Ross 308) were kept under conventional conditions and were orally co-inoculated on day three of the trial with 10^4,10^3, 10^2, or 10^1 colony forming units (cfu) of one ESBL- (CTX-M-15) and one pAmpC- (CMY-2) producing E. coli strain in separate trials. All investigated bacterial counts led to the colonization of all broiler chickens in the trials, with all broiler chickens tested positive after 24 h (10^4-10^2 cfu) or 72 h (10^1 cfu) post inoculation (p.i.) up to the end of each trial. At necropsy (14 d p.i.), the cecal colonization with the ESBL- and pAmpC- producing E. coli strains of all investigated bacterial counts showed equivalence in the statistical analysis. To assure stable colonization, the bacterial count of 10^2 cfu ESBL- and pAmpC- producing E. coli was chosen to establish the seeder-bird model. An inoculation of one-fifth of the day-old broiler chickens with 10^2 cfu E. coli led to the colonization of all inoculated broiler chickens (seeder-birds) after 24 h p.i. and all non-inoculated broiler chickens (sentinel-birds) after 72 h p.i. up to the end of the trial. At necropsy (35 d p.i.) no significant differences in the cecal colonization with the ESBL- and pAmpC producing E. coli strains was apparent between the seeder-birds or sentinel-birds. Distinct intervention measures were subsequently investigated on their potential to reduce the colonization of broiler chickens with ESBL- and pAmpC- producing E. coli throughout the fattening process using the established seeder-bird model. Applying a complex, non-defined Competitive Exclusion-culture led to a significant reduction of both the ESBL- and pAmpC- producing E. coli strain in our trial. Applying a single CE-strain or reducing the stocking density to 25 kg/sqm led to a strain-dependent reduction of the ESBL- E. coli strain but had no impact on the colonization with the pAmpC- E. coli strain. No effect on the colonization of broiler chickens with ESBL- and pAmpC- producing E. coli was evident for the use of an alternative, slower-growing broiler breed (Rowan x Ranger). A negative effect on the colonization of broiler chickens with ESBL- and pAmpC- producing E. coli was shown for the application of a tripled amount of litter in the pen and the acidification of the drinking water with a commercially available product. The minimal bacterial counts of 10^1 to 10^2 cfu ESBL- and pAmpC- producing E. coli highlight the need for effective intervention measures to reduce the broiler chickens’ colonization with ESBL- and pAmpC- producing bacteria including improved biosecurity- and disinfection measures. A promising approach is the application of a Competitive Exclusion-culture, whereas other separately applied management measures were not capable of reducing the broiler chickens’ colonization with both the ESBL- and pAmpC- producing E. coli strains. It needs further investigations whether a combination of different measures can contribute to a reduced colonization of the broiler chickens’ with ESBL- and pAmpC- producing bacteria.