In vitro microbiological characterization of a novel azalide, two triamilides and an azalide ketal against bovine and porcine respiratory pathogens

The Journal of Antibiotics
L J NorciaShigeru F Hayashi

Abstract

Several novel 15-membered-ring macrolide agents (azalide 1, triamilides 2 and 3, and the azalide 3,6-ketal 4) were identified as potential antibacterial agents against Mannheimia (formerly named as Pasteurella) haemolytica, Pasteurella multocida, Haemophilus somnus and Actinobacillus pleuropneumoniae, important etiological agents of bovine and porcine respiratory disease. Compound 3 is the major component of the antibiotic tulathromycin. Antibacterial activity against tilmicosin-resistant P. multocida field isolates was also tested. In vitro MIC 50/90 analysis revealed that the four newly synthesized compounds were more potent than tilmicosin against M. haemolytica (4 to approximately 8x), P. multocida (8 to approximately 16x), A. pleuropneumoniae (4x), H. somnus (2x and 16x), and tilmicosin-resistant P. multocida (32x). In time-kill kinetic studies, all four novel compounds and tilmicosin showed bactericidal activity against M. haemolytica, P. multocida and A. pleuropneumoniae at both 4x and 8x MIC. A functional assay using genetically defined mutants revealed that all four novel compounds were poorer substrates for the efflux pump, AcrA/B system, than tilmicosin. A pH study using LPS mutants indicated that the enhanced in vit...Continue Reading

Citations

Nov 26, 2013·The Veterinary Journal·Nicolas VillarinoTomás Martín-Jiménez
Apr 27, 2010·BMC Microbiology·Saira AhmadMonique L van Hoek
Feb 2, 2010·The Veterinary Clinics of North America. Food Animal Practice·Jeffrey L Watts, Michael T Sweeney
May 26, 2005·The Journal of Antimicrobial Chemotherapy·Keith Poole
Apr 15, 2015·Antimicrobial Agents and Chemotherapy·Nicolas VillarinoNathan W Schmidt
Sep 12, 2017·Journal of Veterinary Pharmacology and Therapeutics·J WangX Cao

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