Sensitivity of Australian Melissococcus pluton isolates to oxytetracycline hydrochloride

Abstract

Summary. The effectiveness of the antibiotic oxytetracycline hydrochloride) against the bacterium Melissococcus pluton, which causes European foulbrood in honey bees (Apis mellifera) was investigated in this study. The minimum inhibitory concentration of oxytetracycline hydrochloride for 104 M. pluton isolates cultured from samples of brood and honey collected from A. mellifera colonies in New South Wales, Victoria, South Australia and Tasmania was determined. The minimum inhibitory concentration was 1 g/mL for 51 isolates, and 2 g/mL for 53 isolates. These results indicate that, although oxytetracycline hydrochloride has been used exclusively for the past 22 years to treat European foulbrood, Australian isolates of M. pluton are still sensitive to this antibiotic.