5-O-Mycaminosyltylonolide antibacterial derivatives: design, synthesis and bioactivity.

Tylosin is a 16-membered macrolide broad-spectrum antibiotic that has an important role in veterinary medicine, active against Gram-positive and a restricted range of Gram-negative bacteria. We synthesized 15 types of tylosin-related derivatives by chemical modification and evaluated them against mastitis pathogens. Among them, 20-deoxy-20-{N-methyl-N-[1-(3-quinolyl)-1H-1,2,3-triazol-4-yl]methylamino}-5-O-mycaminosyltylonolide 2f and 20-deoxy-20-{N-benzyl-N-[1-(3-quinolyl)-1H-1,2,3-triazol-4-yl]methylamino}-5-O-mycaminosyltylonolide 2k were found to not only expand their antibacterial impact to include Gram-negative bacteria, such as Escherichia coli and Klebsiella pneumoniae, but also to retain or increase antibacterial activity against Gram-positive bacteria, such as Staphylococcus aureus and Streptococcus uberis in comparison with the parent tylosin.

The intramammary efficacy of first generation cephalosporins against Staphylococcus aureus mastitis in mice.

Staphylococcus aureus-induced mastitis in cattle causes important financial losses in the dairy industry due to lower yield and bad milk quality. Although S. aureus is susceptible to many antimicrobials in vitro, treatment often fails to cure the infected udder.

Efficacy of four enrofloxacin treatment regimens against experimental infection in turkey poults with avian pneumovirus and Ornithobacterium rhinotracheale.

Drinking-water treatment with enrofloxacin is widely used to cure respiratory infections in turkeys. The current treatment regimen advises a 5-day treatment at 10 mg/kg body weight. Since enrofloxacin exerts a concentration-dependent activity it might be useful to provide the total treatment dose of 50 mg/kg total dose in a single-day treatment regimen.

The effect of reduced treatment time and dosage of enrofloxacin on the course of respiratory disease caused by avian metapneumovirus and Ornithobacterium rhinotracheale.

A dose titration and reduced duration medication study were performed to evaluate the current enrofloxacin treatment schedule in growing turkeys experimentally infected with avian metapneumovirus and Ornithobacterium rhinotracheale. Experimental groups of 17 four-week-old turkeys were first infected with avian metapneumovirus and 3 d later with O. rhinotracheale.

Effect of multiple- and single-day enrofloxacin medications against dual experimental infection with avian pneumovirus and Escherichia coli in turkeys.

Escherichia coli infections are a common cause of respiratory disease in turkeys. To control these respiratory infections in turkeys, drinking water treatment with enrofloxacin is widely used. The current treatment schedule advises a 5-d treatment at 10 mg/kg of BW.