Emergence of bla_OXA−181-bearing tigecycline-resistant Klebsiella aerogenes in China

We report the isolation of a bla_OXA−181-positive, tigecycline-resistant Klebsiella aerogenes strain KA04 from a Chinese inpatient’s fecal sample. Species identification was performed using MALDI-TOF MS. The antibiotic susceptibilities were assessed via the broth microdilution method. To elucidate the transmission and genetic structure of the bla_OXA−181 gene, conjugation assays and whole-genome sequencing (WGS) were performed. KA04 displayed resistance to carbapenems, quinolones, piperacillin/tazobactam and tigecycline. Through WGS and conjugation experiments, it was possible to confirm bla_OXA−181 and qnrS1 genes causing antibiotic resistance were located on a 51-kb IncX3 type mobile plasmid, bla_OXA−181 gene could be successfully transferred into E. coli EC600 at a conjugation frequency of 1.1 × 10^− 4. tet(A) gene was located on both the chromosome and non-transmissible IncFIB(K) plasmid. This is a tigecycline-resistant K. aerogenes harboring bla_OXA−181 isolate from human fecal sample, highlighting a significant public health concern. Further comprehensive surveillance is needed.