In vitro antibiotic sensitivity of Mycoplasma conjunctivae and some bacterial species causing ovine infectious kerato-conjunctivitis

Abstract

Minimum inhibitory concentrations (MICs) and minimum mycoplasmacidal concentrations (MMCs) of six strains of Mycoplasma conjunctivae to eight antibiotics, some of which are incorporated in local and systemic preparations and used in the treatment of ovine infectious keratoconjunctivitis (OIKC) were studied. Tylosin had the lowest MIC, ranging from 0.19–0.39 μg/ml and an MMC of 1.5–3.1 μg/ml, followed by oxytetracycline with an MIC of 0.78–6.2 μg/ml an an MMC of 12.5–50 μg/ml. In similar qualitative antibiotic disc sensitivity tests using the same antibiotics, performed on strains of bacteria found to be significantly associated with OIKC, variable zones of inhibition were produced by most of the antibiotics tested. It was concluded that tylosin, oxytetracycline, streptomycin, and chlortetracycline look suitable for the treatment of OIKC.