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ARS Home » Research » Publications at this Location » Publication #121267
Title: ANTIBIOTIC EFFECTS OF TYLOSIN IN THE LARGE INTESTINE OF SWINE FED SUB-THERAPEUTIC CONCENTRATIONS OF TYLAN

Author
item HOWARD, MICHAEL
item ZAHN, JAMES
item HARRIS, D - IOWA STATE UNIVERSITY

Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 7/24/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The objectives of this study were to: 1) measure the concentration of tylosin and bioactive tylosin metabolites in the large intestine of pigs fed typical corn-soy finishing diet, containing a sub-therapeutic level of tylosin (20 g/907 kg of feed); 2) determine the in vitro minimum inhibitory concentration (MIC) for Micrococcus luteus and Brachyspira hyodysenteriae. Large intestinal digesta of three pigs (107.0 kg +/- 2.0) were solvent-extracted and antibacterial compounds were isolated by coupled preparative reverse-phase liquid chromatography (P-RPLC) followed by a plate diffusion assay with M luteus as the indicator microorganism. Four major bioactive fractions were purified to homogeneity by a second P-RPLC step and sructures of the compounds were assigned using electrospray- ionization tandem mass spectrometry (MS-MS). The identity, concentration, and yield of bioactive compounds purified from the digesta were: Tylosin A (112.2 +/- 8.2 mg/kg, yield = 74%); tylosin D (241.6 +/- 19.3 mg/kg, yield = 81%); demycarose-tylosin A (36.0 +/- 2.3 mg/kg, yield = 78%); and demycarose-tylosin D (21.0 +/- 1.3 mg/kg, yield = 79%). The MIC of purified tylosin A for M luteus was found to be 4.3 +/- 1.3 mg/kg, and the MIC for B hyodysenteriae was found to be 1.1 +/- 0.4 mg/kg. The MIC of the four bioactive compounds were found to be statistically (a = 0.05) identical in MIC assays performed using M luteus. Therefore, the normalized concentration of all bioactive forms of tylosin was used to estimate potential sub-therapeutic effects of tylosin on susceptible bacteria in the gut of swine. The total concentration (0.52 mg/kg) of all bioactive forms of tylosin was found to be in the MIC range of B hyodysenteriae (1.0 +/- 0.6 mg/kg).