Emergence of blaNDM-9-bearing tigecycline-resistant Klebsiella aerogenes of chicken origin.

OBJECTIVES

The aim of this study was to characterise a tigecycline-resistant blaNDM-9-bearing Klebsiella aerogenes strain (HNHF1) of chicken origin.

METHODS

Strain HNHF1 was characterised by phenotypic antimicrobial susceptibility testing, PCR, conjugation assays, S1 nuclease pulsed-field gel electrophoresis (S1-PFGE), whole-genome sequencing and bioinformatics analysis.

RESULTS

The blaNDM-9 gene was located on an IncHI2 plasmid (pHNHF1_NDM-9) carrying various antimicrobial resistance genes. Moreover, the genetic context ΔISAba125-blaNDM-9-bleMBL-trpF is similar to other blaNDM-bearing genetic contexts. TA cloning experiments showed that tet(A) variants may play a partial role in high-level tigecycline resistance in HNHF1.

CONCLUSION

This is the first report of a tigecycline-resistant blaNDM-9-bearing IncHI2 plasmid in a K. aerogenes ST4 isolate of animal origin, which poses a great threat to public health. Further comprehensive surveillance is needed.