Thioether derivatives of tylosin and demycarosyltylosin were synthesized by Michael-type addition of thiol to C-11 of the enone moiety on the aglycone. Some of tylosin derivatives were effective to macrolide resistant Staphylococcus aureus, and their in vivo activities were same or superior than that of tylosin.

Batch culture fermentations were used to determine the effects of avoparcin, lasalocid, monensin, narasin, salinomycin, thiopeptin, tylosin, virginiamycin, monensin + tylosin combination, and two new ionophore compounds (RO22-6924/004 and RO21-6447/009) on lactic acid and volatile fatty acid (VFA) production. Ruminal fluid from cattle fed a high alfalfa hay diet was incubated with glucose for 1...

The minimal inhibitory concentrations (MICs) of tylosin were determined to 67 strains of Paenibacillus larvae subsp. larvae, the causal agent of American Foulbrood (AFB) disease, from different geographical origins. MIC values obtained ranged from 0.0078 to 0.5 microg/ml. These very low values imply that no resistance to tylosin was found in any isolate of the Foulbrood pathogen. The measuremen...

Four feedlot experiments with 774 cattle have been completed during 1969 to 1970 evaluating two forms of tylosin activity (50, 75 and 100 mg per head per day continuously of tylosin phosphate or tylosin urea adduct) in high concentrate rations. Continuous administration of these three levels of antibiotic activity from either form of tylosin (1) reduced the incidence of liver abscesses, (2) inc...

Two mutants of the tylosin-producing Streptomyces fradiae defective in the biosynthesis of the macrolide antibiotic tylosin were isolated from colonies derived from regenerated protoplasts. Both strains were unable to carry out any of at least seven tylosin biosynthetic steps and were sensitive to tylosin. One strain, JS82, was also more sensitive to chloramphenicol (Cm), mitomycin C (Mc), hygr...

Fourteen trials were conducted to evaluate the effects of feeding monensin at 33 ppm alone, tylosin at 11 ppm alone and the two feed additives in combination on the average daily gain, average daily feed intake, feed:gain ratio and the incidence of liver abscesses in feedlot cattle. Monensin reduced feed intake and improved feed efficiency (P less than .05), and had no effect on average daily g...

bacterial spores. The results indicate that tylosin is strongly inhibitory. Additional tests confirm the adjuvant effect of nisin and heat on spores of Bacillus stearothermophilus. These tests also show that tylosin has marked stability to heat as compared to the lesser heat stability of nisin. The ability of tylosin to prevent the outgrowth of naturally occurring thermophilic spores in a comme...

The antimicrobial susceptibilities of 421 Pasteurella haemolytica and 158 P. multocida isolates recovered from cattle with respiratory disease were determined with a microdilution minimal inhibitory concentration test system. Isolates were analyzed for patterns of resistance to ampicillin, ceftiofur, erythromycin, gentamicin, penicillin, spectinomycin, sulfachlorpyridazine, sulfadimethoxine, te...

The effects of the antimicrobial tylosin on a methanogenic microbial community were studied in a glucose-fed laboratory-scale anaerobic sequencing batch reactor (ASBR) exposed to stepwise increases of tylosin (0, 1.67, and 167 mg/L). The microbial community structure was determined using quantitative fluorescence in situ hybridization (FISH) and phylogenetic analyses of bacterial 16S ribosomal ...

Objective. To compare four different dry cow treatments (DCT) and establish their effectiveness in reducing intramammary infections (IIM). Materials and methods. DCTs included systemic tylosin (12g) alone or accompanied by cefapirine intramammary infusions and or an internal teat sealant. A total number of 278 cows at the end of lactation period were randomly assigned to one of 4 dry cow treatm...