Characterization of a Plasmid-Encoded Resistance-Nodulation-Division Efflux Pump in Klebsiella pneumoniae and Klebsiella quasipneumoniae from Patients in China

Two multidrug-resistant (MDR) mcr-1 -harboring Klebsiella pneumoniae isolates from patients with urinary tract infections and one MDR Klebsiella quasipneumoniae isolate from a patient with bloodstream infection were identified to carry tmexCD1-toprJ1 . The addition of the efflux pump inhibitor reduced the tigecycline MIC against all three isolates by 8- to 16-fold. pKQBSI104-1 was transferred from K. quasipneumoniae to Escherichia coli J53 via conjugation.