In-vitro antibacterial properties of tilmicosin against Australian isolates of Pasteurella multocida and Actinobacillus pleuropneumoniae from pigs

Abstract

Tilmicosin is a new macrolide antibiotic prepared by chemicalmodifications of desmycosin (Ose 1987; Debono et,al 1989) and isthe actiye ingredient of both Micotil300@Injection and Pulmotil@Premix . While Micotil 300@should not be administered to swine,Pulmotil@Premix is an oral formulation of tilmicosin that has beendeveloped for the treatment of porcine respiratory disease. Field trialsevaluating Pulmotil@ Premix are being conducted in at least tencountries around the world before applications for registration arelodged.

Studies performed overseas have established that tilmicosin has anantimicrobial spectrum characteristic of macrolide antibiotics. Ose(1 987) and Debono ei a/ (1 989) have demonstrated that tilmicosininhibited the growth of isolates of Pasteurella multocida, Pastewellahaemolytica, Mycoplasrna hyopneumoniae, Actinobaciflus pleuro-pneumoniae, Streptococcus suis and Actinomyces pyogenes, generallyat concentrations of 6.25 pg/mL or less. Stephens et al(l993) haveshown that tilmicosin is active in vitro against isolates of P multocidaand P haemolytica obtained from Australian cattle, with all isolatesbeing inhibited at 6.25 pg/mL or less. In this paper, we report on thein-vitro antibacterial activity of tilmicosin against 50 isolates of Apleuropneumoniae and 51 isolates of P multocida, all obtaiped fromAustralian pigs.