Coexistence of tmexCD-toprJ , bla NDM-1 , and bla IMP-4 in One Plasmid Carried by Clinical Klebsiella spp

In clinical practice, carbapenems and tigecycline are considered significant options for treating infections caused by multidrug-resistant spp. The continual evolution of resistance mechanisms to carbapenems and tigecycline is shattering the present condition. Meanwhile, convergence of the two resistance mechanisms in a single strain has been reported repeatedly, posing a significant threat to public health and safety. In this study, two carbapenem- and tigecycline-resistant species were obtained from patients and investigated using antimicrobial susceptibility testing, conjugation assay, whole-genome sequencing, and bioinformatics analysis. In Klebsiella variicola FK2020ZBJ35, an untransferable multidrug IncFIB(Mar)/IncHI1B-like plasmid carrying , , and was discovered, as was a similar plasmid carrying and in Klebsiella quasipneumoniae 2019SCSN059. Genetic context analysis found that two distinct variants were detected in comparable mobile units with genetic array and integrated into separate genetic locations. and were carried by an integron In and a truncated Tn , respectively. These findings revealed that the carbapenem and tigecycline resistance genes carried by the two strains were located on mobile elements and might potentially transmit horizontally to additional strains. Furthermore, our findings showed that IncFIB(Mar)/IncHI1B-like plasmids represent a significant reservoir of essential resistance genes that warrants continued monitoring. Tigecycline is an essential antibiotic that is used to treat infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP). The emergence of high-level tigecycline-resistant CRKP poses a serious hazard to human health. This work screened two tigecycline-resistant CRKP strains from clinical patients and found a type of plasmid that encoded carbapenemase and TmexCD-ToprJ in . Importantly, one plasmid cocarried , , and , hinting that this plasmid could be a critical vector for superbug development. Furthermore, we discovered that the carbapenem and tigecycline resistance genes are located in mobile units by genetic structure analysis. Our research tracks the formation of clinically super-resistant Gram-negative bacteria.