SmvA is an important efflux pump for cationic biocides in Klebsiella pneumoniae and other Enterobacteriaceae

Matthew Wand*, Shirin Jamshidi, Lucy Bock, Khondaker Miraz Rahman, J. Mark Sutton

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


The multidrug resistant (MDR) opportunistic pathogen Klebsiella pneumoniae has previously been shown to adapt to chlorhexidine by increasing expression of the MFS efflux pump smvA. Here we show that loss of the regulator SmvR, through adaptation to chlorhexidine, results in increased resistance to a number of cationic biocides in K. pneumoniae and other members of the Enterobacteriaceae. Clinical Enterobacteriaceae isolates which lack smvA and smvR also have an increased susceptibility to chlorhexidine. When smvA from Salmonella and K. pneumoniae are expressed in Escherichia coli, which lacks a homologue to SmvAR, resistance to chlorhexidine increased (4-fold) but plasmid carriage of smvA alone was detrimental to the cell. Challenge of K. pneumoniae with chlorhexidine and another cationic biocide, octenidine, resulted in increased expression of smvA (approx. 70 fold). Adaptation to octenidine was achieved through mutating key residues in SmvA (A363V; Y391N) rather than abolishing the function of SmvR, as with chlorhexidine adaptation. Molecular modelling was able to predict that octenidine interacted more strongly with these mutated SmvA forms. These results show that SmvA is a major efflux pump for cationic biocides in several bacterial species and that increased efflux through SmvA can lead to increased chlorhexidine and octenidine tolerance.

Original languageEnglish
Article number1344
JournalScientific Reports
Issue number1
Publication statusPublished - 1 Dec 2019

Bibliographical note

Funding Information:
This project was funded by Public Health England GIA grant project 109506. The views expressed are those of the authors and not necessarily those of the funding body.

Publisher Copyright:
© 2019, The Author(s).


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