Mapping the resistance-associated mobilome of a carbapenem-resistantKlebsiella pneumoniaestrain reveals insights into factors shaping these regions and facilitates generation of a ‘resistance-disarmed’ model organism

Abstract

This study has reiterated the role of plasmids as bearers of the vast majority of resistance genes in this species and has provided valuable insights into the vital role played by ISs, transposons and integrons in shaping the resistance-coding regions in this important strain. The 'resistance-disarmed' K. pneumoniae ST11 strain generated in this study will offer a more benign and readily genetically modifiable model organism for future extensive functional studies.

Identification and characterization of acetyltransferase‐type toxin‐antitoxin locus in Klebsiella pneumoniae

“…To explore whether kacAT is a bona fide TA locus, the K. pneumoniae HS11286 mutant HS11286‐RR2 was employed, in which the plasmid‐carrying bla KPC‐2 and 26‐kb multiple drug resistance regions were deleted. This manipulation allowed a flexible use of antibiotic selection markers (Bi et al ., ). The GNAT domain toxin gene, kacT ( KPHS_05890 ), was amplified and inserted downstream of arabinose‐inducible araBAD promoter of pBAD33 (Guzman et al ., ).…”

“…RT‐PCR analysis of total RNA isolated from K. pneumoniae HS11286‐RR2 (Bi et al ., ) at the logarithmic growth phase with specific primers spanning the toxin and antitoxin genes showed that kacAT gene pair was co‐transcribed as a bicistronic operon (Fig. B and C).…”

“…E. coli strain BL21(DE3) (Novagene) was used for protein expression. HS11286‐RR2Δ kacAT was constructed using a markless gene deletion technique with the combination of the lambda red recombination and flippase (Flp) recombinase‐based recombination methods (Bi et al ., ). Briefly, the kacAT locus was replaced by the hygromycin resistance gene flanked by the flippase recognition target (FRT) site using the lambda red recombination, and then the hygromycin resistance gene was eliminated via the Flp‐FRT recombination.…”

“…In particular, as the name suggests, it is known to cause pneumonia (Gomez‐Simmonds and Uhlemann, ). Dramatically increased incidence of K. pneumoniae resistance to multiple antibiotics, particularly to the agents of last resort, such as carbapenems (Bi et al ., ), poses a significant emerging global problem (Anonymous, ). K. pneumoniae devises various strategies to adapt to the action of various antimicrobial compounds, including TA system regulation (Navon‐Venezia et al ., ).…”

Initial Assessment of the Molecular Epidemiology of bla NDM-1 in Colombia

“…1). We interpret this to be a consequence of insertion of Tn125 within a Tn5393-like structure, as evidenced by the presence of tnpA, tnpR, strA, and strB, characteristic of this Tn3 transposon, originally reported for Erwinia amylovora (23), but now found in several Gram-negative species in clinical, ecological, and agricultural niches (24)(25)(26)(27). This complex array of transposons is followed by an aminoglycoside resistance gene (aadA16) flanked by transposable genetic elements, indicating that this whole region could be serving as a "hot spot" for the incorporation of genetic determinants either by homologous recombination via IS elements, site-specific recombination, or transposition.…”