Table 1.

A summary of the most important studies conducted in recent years on the effect of AMPs on colistin-resistant Gram-negative bacteria

Name of author	Year	Name of AMPs	Organism	Result	Reference
Jahangiri et al	2021	Nisin and P10	XDR A. baumannii and colistin-resistant P. aeruginosa isolates	AMPs, alone and in combination with antibiotics showed the ability to kill mentioned bacteria	(Jahangiri et al. 2021)
Conlon et al	2012	CPF-AM1, PGLa-AM1, B2RP-ERa, [E4K] alyteserin-1c, [D4K] B2RP, and [G4K] XT-7	Colistin-resistant clinical isolates of A. baumannii and Acinetobacter nosocomialis	All six AMPs had an effect on colistin-resistant Acinetobacter isolates	(Conlon et al. 2012)
Lin et al	2018	WLBU2 and LL37	Colistin-resistant isolates of K. pneumoniae, A. baumannii, and P. aeruginosa	The two studied AMPs showed a significant effect on colistin-resistant isolates of A. baumannii and K. pneumoniae but were not able to kill P. aeruginosa	(Lin et al. 2018)
Weide et al	2019	AA139 and SET-M33	Colistin-resistant and mcr-producing isolates of K. pneumoniae	AMPs were effective against colistin-resistant strains in MIC ≥ 16 µg/L	(van der Weide et al. 2019)
Witherell et al	2020	MSI-78 and OTD-244	Colistin-resistant E. coli, K. pneumoniae, A. baumannii, and P. aeruginosa	The MSI-78 alone and combination with colistin showed great antibacterial activity against colistin-resistant bacteria	(Witherell et al. 2020)
Kádár et al	2015	Protamine, lysozyme, and lactoferrin	Colistin-resistant K. pneumoniae and E. asburiae	Protamine and lysozyme were effective against colistin-resistant K. pneumoniae but all three AMPs were not able to eradicate colistin-resistant E. asburiae	(Kádár et al. 2015)
Hashemi et al	2017	LL-37, Cecropin A, Magainin 1, CSA-13, CSA-44, CSA-131, CSA-138, and CSA-142	Colistin-resistant K. pneumoniae	AMPs kill colistin-resistant K. pneumoniae via lipid A modifications	(Hashemi et al. 2017)
Cirioni et al	2011	S-thanatin	Colistin-resistant P. aeruginosa	The s-thanatin alone and in combination with colistin showed the highest efficacy in vitro and in vivo	(Cirioni et al. 2011)
Deslouches et al	2015	WLBU2, WR12, and LL37	Colistin-resistant MDR pathogenic bacteria	WLBU2 and WR12 as two engineered cationic AMPs display better antibacterial activity (80 to 86%) than LL37 (25%) as natural AMPs against colistin-resistant strains	(Deslouches et al. 2015)
Hirsch et al	2019	LS-sarcotoxin and LS-stomoxyn	Colistin-resistant MDR Gram-negative bacteria	LS-sarcotoxin and LS-stomoxyn have selective and potent activity against colistin-resistant MDR Gram-negative bacteria	(Hirsch et al. 2019)
Mant et al	2019	D87(Lys1-6 Arg-1), D84(Lys1-6 Lys-1), D85(Lys1-6 Orn-1), D86(Lys1-6 Dab-1), D105(Lys1-6 Dap-1), D101(Lys1Ser26-5 Lys-1), D102(Lys1Ser26-5 Dab-1), D85(K13A/K16A)-(Lys1-6 Orn-1), D86(K13A/K16A)-(Lys1-6 Dab-1), and D105(K13A/K16A)-(Lys1-6 Dap-1)	polymyxin B- and colistin-resistant A. baumannii strains	All of studied AMPs presented excellent antimicrobial activity on polymyxin B- and colistin-resistant A. baumannii strains	(Mant et al. 2019)
Kao et al	2016	LL-37, RL-37, LL-29, LL-29 V, LL-29V2, CAP-11, CAP-11V1, CAP-11V2, CAP-11V3, SMAP-29, SMAP-29 V, SMAP-29B, SMAP-29D, BMAP-27, BMAP-27A, BMAP-27B, and BMAP-27C	The mcr-harboring and colistin-resistant E. coli	BMAP-27B and SMAP-29D showed bactericidal activity against colistin-resistant E. coli	(Kao et al. 2016)
Hirsch et al	2020	EtCec1-a and EtCec2-a	Colistin-resistant E. coli, E. cloacae, E. aerogenes, K. pneumoniae, S. enterica, S. maltophilia and A. baumannii	Two AMPs displayed antimicrobial activity against the colistin-resistant isolates	(Hirsch et al. 2020)
Mourtada et al	2019	Mag (i + 4)1,15 (A9K,B21A,N22K,S23K)	Colistin-resistant E. coli and A. baumannii	AMP showed potential bactericidal activity on two studied colistin-resistant pathogens in vitro and colistin-resistant A. baumannii in a murine peritonitis-sepsis model	(Mourtada et al. 2019)