Skip to main content
SLU publication database (SLUpub)

Research article2011Peer reviewedOpen access

Antimicrobial susceptibility of Brachyspira spp. isolated from commercial laying hens and free-living wild mallards (Anas platyrhynchos)

Jansson, Monica Desiree Seger; Pringle, Märit

Abstract

In vitro antimicrobial susceptibility to tylosin, valnemulin, tiamulin, doxycycline, lincomycin and ampicillin was investigated by broth dilution in 48 Brachyspira spp. isolates from commercial laying hens (n = 30) and free-living wild mallards (Anas platyrhynchos) (n = 18). Presumed pathogens (Brachyspira alvinipulli, Brachyspira intermedia, Brachyspira pilosicoli), commensals (Brachyspira murdochii, Brachyspira innocens, "Brachyspira pulli''), and isolates of undetermined species affiliation were included. The laying hens had not been exposed to therapeutic levels of antimicrobials for at least 50 weeks before sampling, and low levels of environmental antimicrobial exposure were presumed in mallards. No isolates with decreased susceptibility to tylosin, valnemulin, tiamulin or doxycycline were found. Decreased susceptibility to lincomycin (minimum inhibitory concentration 16 mu g/ml) was detected in two isolates (Brachyspira sp.) from laying hens. Five isolates showed decreased susceptibility to ampicillin (minimum inhibitory concentration 16 to >32 mu g/ml), including two "B. pulli'' and one B. alvinipulli from laying hens, and isolates of B. pilosicoli and "B. pulli'' from mallards. Decreased susceptibility to ampicillin was associated with beta-lactamase activity in four isolates. A new variant of a class D beta-lactamase gene designated bla(oxa-192) was identified in a B. pilosicoli isolate of mallard origin. This is the first time the genetic basis for antimicrobial resistance is described in Brachyspira spp. from a free-living wild bird. Isolates displaying decreased susceptibility to ampicillin were accompanied by fully susceptible isolates of the same species or other genotypes within three laying hen flocks. This underlines the need for performing antimicrobial susceptibility tests on single clones/genotypes, and to analyse multiple isolates from the same flock.

Published in

Avian Pathology
2011, Volume: 40, number: 4, pages: 387-393
Publisher: TAYLOR & FRANCIS LTD

      SLU Authors

      • Associated SLU-program

      AMR: Bacteria

      Sustainable Development Goals

      SDG3 Ensure healthy lives and promote well-being for all at all ages

      UKÄ Subject classification

      Veterinary Science
      Animal and Dairy Science

      Publication identifier

      DOI: https://doi.org/10.1080/03079457.2011.588197

      Permanent link to this page (URI)

      https://res.slu.se/id/publ/58588