Wild-type cutoff for Apramycin against Escherichia coli [post]

Xiuying Zhang, Yuqi Yang, Tianshi Xiao, Jiarui Li, Ping Cheng, Fulei Li, Hongxiao Yu, Ruimeng Liu, Ishfaq Muhammad
2020 unpublished
Background Apramycin is used exclusively for the treatment of Escherichia coli ( E.coli ) infections in swine around the world since the early 1980s. Recently, many research papers have demonstrated that apramycin has obvious in vitro activity against multidrug-resistant Enterobacteriaceae isolated in hospitals. Therefore, ensuring the proper use of apramycin in veterinary clinics is of great significance of public health. The objectives of this study were to develop a wild-type cutoff for
more » ... ype cutoff for apramycin against E.coli using a statistical method recommended by Clinical and Laboratory Standards Institute (CLSI) and to investigate the prevalence of resistance genes that confer resistance to apramycin in E. coli . Results Antibacterial susceptibility testing of 1230 E.coli clinical isolates from swine were determinded by broth microdilution testing according to the CLSI document M07-A9. A total number of 310 E.coli strains from different minimum inhibitory concentration (MIC) subsets (0.5-256 µg/mL) were conveniently selected for the detection of resistance genes ( aac(3)-IV ; npmA ; apmA ) in E. coli by PCR. The percentage at each MIC (0.5, 1, 2, 4, 8, 16, 32, 64, 128, and 256 µg/mL) was 0.08%, 0.08%, 0.16%, 2.93%, 31.14%, 38.86%, 12.85%, 2.03%, 1.46%, and 10.41%. The MIC 50 and MIC 90 were 16 and 64 µg/mL. All the 310 E.coli isolates were negative for npmA and apmA gene, and only the aac(3)-IV gene was detected in this study. Conclusions The wild-type cutoff for apramycin against E.coli was defined as 32 µg/mL. The prevelance of aac(3)-IV gene mainly concentrated in these MIC subsets 'MIC ≥ 64 µg⁄ mL', which indicates that the wild-type cutoff established in our study is reliable. The wild-type cutoff offers interpretion criteria of apramycin susceptibility testing of E.coli .
doi:10.21203/rs.3.rs-20198/v1 fatcat:wqelksejurfzvijvveieljshmy