Changes of Sensitivity to Streptomycin in Erwinia amylovora Isolated from 2019 to 2023 in Korea

Abstract

Erwinia amylovora, a causal pathogen of fire blight, has been continuously inducing damage to the apple and pear trees in South Korea since 2015. Farmers apply antibiotics during blooming season to prevent the fire blight. However, continuous use of antibiotics can induce the emergence of resistant bacteria, which consequently reduces control efficacy. In this study, we assessed the minimal inhibitory concentration (MIC) of streptomycin, using a total of 361 E. amylovora isolates that were collected from the six provinces of South Korea from 2019 to 2023. As a result, the MIC of streptomycin ranged from 0.5 to 4 µg/ml and the strA-strB genes were not identified from the isolates. The MIC was higher in the isolates from Gyeonggi-do, Gangwon-do, and Chungcheongbuk-do compared to those from other three provinces. These results may bring broad attention to the use of streptomycin and aid in developing a management protocol for the occurrence of fire blight in South Korea.

Keywords

• antibiotics
• antimicrobial resistance
• fire blight