Susceptibility of bacteria isolated from pigs to tiamulin and enrofloxacin metabolites

Anne Kruse Lykkeberg, Bent Halling-Sørensen, Lars Bogø Jensen

Research output: Contribution to journalJournal articleResearchpeer-review


:Susceptibilities to metabolites of tiamulin (TIA) and enrofloxacin (ENR) were tested using selected bacteria with previously defined minimal inhibitory concentrations,(,MIC). The TIA metabolites tested were: N-deethyl-tiamulin (I)TIA), 2 beta-hydroxy-tiamulin (2 beta-HTIA),and Sammhydroxy-tiamulin (8 alpha-HTIA), and the ENR metabolites were: ciprofloxacin (CIP) and enrofloxacin N-oxide (ENR-N). Bacteria, all of porcine origin, we're selected as representatives of bacterial infections (Stap4ylococcus hyicus and Actinobacillus pleuropneumoniae), zoonotic bacteria (Campylobacter coli) and indicator bacteria (Escherichia coli and Furthermore the effects of ithese compounds were tested on the microbial community of active sludge to test any negative effect on colony forming units,(CFU). DTIA had a potency of 12.5-50% of the potency of T1A. 2-HTIA:and 8 alpha HTIA had,potenciesless, than 1% of the potency of TIA. ENR-N had a potency of 0.75-1.5% of the potency of ENR, while CIP and ENR had, similar potencies. Results,obtained here indicate that CIP and DTIA could contribute to the selective pressure for upholding, antimicrobial resistant bacteria in animals under ENR or TIA treatment. The most potent metabolites CIP:and DTIA showed considerable potencies against activated sludge bacteria compared to the parent compounds. EC50 (mu g/ml) for ENR, CIP, TIA,and DTIA were 0.018 [95% CI: 0.028-0.149], 0.064 [95% CI: 0.007 - 0.0461, 6.0 [95% 0:3.6-9:8], and 9.7 [95%,CI; .5.8-16.3], respeaively. This indicates that the compounds can change the,bacterial population,in the,sludge, and hereby falter the properties of the sludge.
Original languageEnglish
JournalVeterinary Microbiology
Issue number1-2
Pages (from-to)116-124
Publication statusPublished - 2007


  • metabolites
  • Actinobacillus pleuropneumoniae
  • tiamulin
  • bacteria
  • Campylobacter coli
  • resistance
  • enrofloxacin


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