Identification of fosA10, a Novel Plasmid-Mediated Fosfomycin Resistance Gene of Klebsiella pneumoniae Origin, in Escherichia coli

Ying Huang,1 Qingqing Lin,1 Qiaoli Zhou,1 Luchao Lv,1 Miao Wan,1 Xun Gao,1 Chengzhen Wang,1 Jian-Hua Liu1,2 1Key Laboratory of Zoonoses, Ministry of Agriculture and Rural Affairs, Guangdong Provincial Key Laboratory of Veterinary Pharmaceutics Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, People’s Republic of China; 2Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, People’s Republic of ChinaCorrespondence: Jian-Hua Liu Email jhliu@scau.edu.cnPurpose: Several subtypes of plasmid-mediated fosfomycin resistance gene fosA in Enterobacteriaceae have been reported worldwide and have caused concern. The present study characterized a novel member of fosA gene located on a plasmid from Escherichia coli.Materials and Methods: A fosfomycin-resistant E. coli isolate PK9 was recovered from a chicken meat sample in 2018. The presence of fosA genes was detected by PCR and sequencing. Whole-genome sequencing (WGS), conjugation, and cloning were performed to identify the mechanism responsible for fosfomycin resistance. Oxford Nanopore MinION sequencing was carried out to characterize the plasmid carrying fosfomycin resistance gene and the genetic context of the novel fosA variant.Results: A novel fosA gene with significant homology (> 98%) with fosA6 and fosA5 genes was identified by WGS and was named fosA10. FosA10 shared 56.1% to 98.6% amino acid sequence identity with other reported plasmid-mediated FosA enzymes. Fosfomycin resistance and fosA10 gene were successfully transferred to E. coli C600 by conjugation. Cloning confirmed that FosA10 could confer fosfomycin resistance (MIC > 128 μg/mL). The fosA10 gene was localized on a 53kb IncFII (F35:A-:B-) plasmid. The ∆lysR-fosA10-∆hp fragment (4328 bp), located between two copies of IS10R, showed 100% identity with the chromosomal sequences of 17 Klebsiella pneumoniae strains of ST664 and one of ST3