The macrolides appear to have considerable effects for treatment of bovine mastitis because of excellent diffusion into the mammary gland, long half-life, low protein binding, high intracellular concentration and lipid solubility. Acquired resistance to macrolides in Staphylococcus aureus is primarily related to target-site modification through acquisition of an erm gene. In the present study t...

A high prevalence of macrolide resistant isolates has been found among staphylococci isolated from animals (4). The erm(C) gene is the most common gene encoding macrolide resistance in staphylococci (8). It is well known that expression of the erm(C) gene is normally regulated by formation of hairpin structures upstream for the erm(C) gene (5,9) rendering the start codon of erm(C) gene non-acce...

Tylosin phosphate is a macrolide commonly administered to cattle in North America for the control of liver abscesses. This study investigated the effect of in-feed administration of tylosin phosphate to cattle at subtherapeutic levels and its subsequent withdrawal on macrolide resistance using enterococci as an indicator bacterium. Fecal samples were collected from steers that received no antib...

The effects of increased concentration of inorganic phosphate on the biosynthesis of tylosin, the level of the intracellular adenylates, the energy charge, and the activities of enzymes involved in the synthesis of tylonolide precursors were studied in Streptomyces fradiae NRRL 2702. No metabolic response was observed when elevated levels of inorganic phosphate were added in idiophase. Increase...

The antibacterial activity of acyl derivatives of tylosin were examined in vitro and in vivo. The 4"-acyl group in the acylated tylosins enhanced the antibacterial activity and antimycoplasmal activity against some macrolide-resistant strains. The orally administered 3-acetyl-4" -isovaleryltylosin produced a higher blood level in mice and rabbits than tylosin and a good therapeutic effect on th...

As one of the widely used veterinary macrolide antibiotics, the environmental risks of tylosin (TYL) received more and more attention. The purpose of the present study was to develop a modified, rapid and precise RP-HPLC method with PDA detection for the determination of the macrolide antibiotic tylosin in liquid samples. The proposed two HPLC methods offered short retention time (< 6.8 min), h...

Tylosin was fed to two of six wethers for 79 days, to a second two for only 28 days, and not at all to a third pair (controls). The addition of tylosin to the daily feed resulted in a rapid twofold increase in protozoal concentration and a change in the composition or characteristics, or both, of the bacterial population. The results indicate that the bacterial population was modified to the ex...

BACKGROUND Streptomyces, as the main source of antibiotics, has been intensively exploited for discovering new drug candidates to combat the evolving pathogens. Disruption of wblA, an actinobacteria-specific gene controlling major developmental transition, can cause the alteration of phenotype and morphology in many species of Streptomyces. One wblA homologue was found in Streptomyces ansochrom...

The growth-inhibiting and binary joint effects of 12 antibacterial agents on the freshwater green alga Pseudokirchneriella subcapitata (Korschikov) Hindák were investigated over 72-h exposures. The toxicity values (the median inhibitory concentration value, in micromoles) in decreasing order of sensitivity were triclosan (0.0018)>triclocarban (0.054)>roxithromycin (0.056)>clarithromycin (0.062)...