Quercetin Rejuvenates Sensitization of Colistin-Resistant Escherichia coli and Klebsiella Pneumoniae Clinical Isolates to Colistin

Colistin is being considered as the last ditch treatment in many infections caused by Gram-negative stains. However, colistin is becoming increasingly invalid in treating patients who are infected with colistin-resistant Escherichia coli (E. coli) and Klebsiella Pneumoniae (K. pneumoniae). To cope with the continuous emergence of colistin resistance, the development of new drugs and therapies is highly imminent. Herein, in this work, we surprisingly found that the combination of quercetin with colistin could efficiently and synergistically eradicate the colistin-resistant E. coli and K. pneumoniae, as confirmed by the synergy checkboard and time-kill assay. Mechanismly, the treatment of quercetin combined with colistin could significantly downregulate the expression of mcr-1 and mgrB that are responsible for colistin-resistance, synergistically enhancing the bacterial cell membrane damage efficacy of colistin. The colistin/quercetin combination was notably efficient in eradicating the colistin-resistant E. coli and K. pneumoniae both in vitro and in vivo. Therefore, our results may provide an efficient alternative pathway against colistin-resistant E. coli and K. pneumoniae infections.

Automated summary

Colistin, considered as a last resort treatment for Gram-negative bacteria infections, is becoming ineffective against colistin-resistant strains of Escherichia coli and Klebsiella Pneumoniae. The combination of quercetin with colistin efficiently eradicates colistin-resistant bacteria by downregulating resistance genes and enhancing bacterial cell membrane damage. This colistin/quercetin combination shows promise as an alternative pathway against colistin-resistant infections.