TABLE 1.

Bacteria resistant to polymyxins and their resistance gene.

Bacteria	Resistance mechanisms	Gene	References
A. baumannii	Modifications of the LPS moiety	pmrA, pmrB, pmrC, mcr	Snitkin et al. (2013), Cheah et al. (2016), Lima et al. (2018)
A. baumannii	lipid A deficiency	lpxA, lpxC, and lpxD	Bojkovic et al. (2015), Jeannot et al. (2017), Sherry and Howden (2018)
A. baumannii	Changes in membrane permeability and Efflux pump systems	lpsB, lptD, and vacJ	Hood et al. (2013), Whitfield and Trent (2014), Thi Khanh Nhu et al. (2016)
Helicobacter pylori	Modifications of the LPS moiety	Cgt, ompD	Sato et al. (2018)
Neisseria meningitidis	Efflux pumps	porB	Tzeng et al. (2005)
Yersinia enterocolitica	RosA/RosB efflux pump/potassium antiporter system	RosA and RosB	Bengoechea and Skurnik (2000)
Pa. polymyxa	Inactivates colistin	Unknown	Sampson et al. (2012), Deris et al. (2014)
P. mirabilis	LPS modification	Proteus pmrI gene	Jiang et al. (2010)
S. marcescens	LPS modification	arnB and arnC	Lin et al. (2014)
K. pneumoniae	Overexpression of PhoP/PhoQ, Inactivation of the mgrB gene	ColR/ColS, blaCTX-M-15 ESBL gene	Gutu et al. (2013), Cannatelli et al. (2014), Jayol et al. (2015a), Jayol et al. (2016), Nordmann et al. (2016)
Klebsiella pneumoniae	Reduces the affinity of antibiotics for cells	mgrB gene	Jayol et al. (2015b), Yap et al. (2022)
Aeromonas spp and Escherichia coli	mcr-variant of the plasmid-mediated	mcr-variant	Belaynehe et al. (2018), Gonzalez-Avila et al. (2021)
P. aeruginosa	LPS modification operon	ParR/ParS	Fernandez et al. (2010)
V. cholera	LPS biosynthesis and modification	gspIEF, lpxN, vc0224/0239/1981	Mlynarcik and Kolar (2019)
Haemophilus influenza	Lipooligosaccharide modifications	lic1/2A, lpsA, lgtF, opsX	Morey et al. (2013)