Complete Genome Sequence and Characterization of Linezolid-Resistant Clinical Isolate KUB3006 Carrying a (B)-Transposon on Its Chromosome and -Plasmid.

Linezolid (LZD) has become one of the most important antimicrobial agents for infections caused by gram-positive bacteria, including those caused by species. LZD-resistant (LR) genetic features include mutations in 23S rRNA/ribosomal proteins, a plasmid-borne 23S rRNA methyltransferase gene , and ribosomal protection genes ( and ). Recently, a gene variant, (B), was identified in a Tn-like transposon (Tn) in a isolate. Here, we isolated an LR clinical isolate, KUB3006, from a urine specimen of a patient with urinary tract infection during hospitalization in 2017. Comparative and whole-genome analyses were performed to characterize the genetic features and overall antimicrobial resistance genes in isolate KUB3006. Complete genome sequencing of KUB3006 revealed that it carried (B) on a chromosomal Tn-like element. Surprisingly, this Tn-like element was almost (99%) identical to that of Ox3196, which was isolated from a human in the UK in 2012, and to that of 5_Efcm_HA-NL, which was isolated from a human in the Netherlands in 2012. An additional oxazolidinone and phenicol resistance gene, , was also identified on a plasmid. KUB3006 is sequence type (ST) 729, suggesting that it is a minor ST that has not been reported previously and is unlikely to be a high-risk lineage. In summary, LR KUB3006 possesses a notable Tn-like-borne (B) and a plasmid-borne . This finding raises further concerns regarding the potential declining effectiveness of LZD treatment in the future.