Search National Agricultural Library Digital Collections
Back to Search
NALDC Record Details:
Transfer of tylosin resistance between Enterococcus spp. during continuous-flow culture of feral or domestic porcine gut microbes
Download [PDF File]
Mixed populations of domesticated and feral pig gut microorganisms (Recombined Porcine-Derived Continuous Flow culture; RPCF and Feral Culture; FC, respectively) were grown in continuous culture to investigate the effects of tylosin on antimicrobial resistance. Cultures established in steady state were inoculated with 9.7 log10 colony forming units (CFU) of a tylosin-resistant Enterococcus faecium and allowed 7 days to re-establish equilibrium before administration of 100 μg tylosin mL-1. Total culturable anaerobes recovered on non-antibiotic supplemented medium, thus inclusive of tylosin-sensitive and -insensitive bacteria, ranged from 7.15 to 9.20 log10 CFU mL-1 throughout 8 days of tylosin administration and 6 subsequent days without tylosin administration. Recovery of total anaerobes on tylosin-supplemented medium revealed that populations of total tylosin-insensitive anaerobes ranged from 6.30 to 9.02 log10 CFU mL-1 during the experiment. Concentrations of the introduced tylosin-resistant E. faecium decreased to near minimum detectable levels (1.3 log10 CFU mL-1) in the cultures before initiation of tylosin administration and then increased to 6.80 ± 0.28 and 8.30 ± 0.43 log10 CFU mL-1 in RPCF and FC cultures, respectively, and remained higher than day 0 concentrations for the remainder of the experiment. Endogenous tylosininsensitive Enterococcus were undetectable before administration of tylosin but tylosin-resistant E. faecalis and E. hirea found to have acquired an ermB gene of expected size and sequence of that contained in the introduced E. faecium were enriched to 7.74 ± 0.37 and 3.85 ± 4.03 after initiation of tylosin administration. These results demonstrate the acquisition, propagation and persistence of tylosin-resistance in mixed populations of domestic and feral swine gut microflora.
R. C. Anderson
D. J. Nisbet
Agriculture 2012 v.2 no.2
Journal Articles, USDA Authors, Peer-Reviewed
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
Agricultural Research Service
Web Policies and Important Links