Table 1.

CDI systems in bacterial species.

	Microorganism	CDI-Related Findings	Reference
Escherichia	E. coli strain EC93	The first description of the CDI phenomenon.	[32]
	E. coli	CDI toxins/receptors complexes.	[40,41,42]
	E. coli	Mechanisms of CDI regulation.	[28,35,36,38,43,47,48]
	E. coli, B. pseudomallei	CDI toxin/immunity protein complexes.	[30,37]
	E. coli strain 536 (UPEC536)	CysK enzyme stabilizes the complex of CdiA-CT with the immunity protein CdiI.	[44,49]
	E. coli strain NC101	CDI toxin/immunity protein/elongation factor Tu complex.	[50]
	E. coli strain Nissle 1917	Identification of functioning cdiA-CT/cdiI modules.	[51]
Burkholderia	B. thailandensis	The “Burkholderia” type of CDI locus is firstly defined. Expression of bcpAIOB genes is required for autoaggregation and adhesion on abiotic surfaces.	[52]
	B. pseudomallei	Ten subtypes of CDI systems within the B. pseudomallei species were identified.	[54]
	B. thailandensis	CdiA toxins probably participate not only in interbacterial competition but also in cooperation and recognition of “self” bacteria from “non-self”.	[53,55,56]
	B. thailandensis	The mechanism of CDI toxin delivery can differ even between closely related species.	[57]
	B. dolosa	Identification of three functioning CDI systems.	[58]
	B. multivorans, B. thailandensis	Non-pathogenic B. thailandensis uses CDI to control the growth of pathogenic B. multivorans during co-cultivation.	[59]
Pseudomonas	P. aeruginosa strain PAO1	Identification of multiple cdi loci in the Pseudomonas genomes. CDI systems are involved in the processes of adhesion and biofilm formation.	[61]
	P. aeruginosa	CDI system is vital for virulence of multidrug-resistant P. aeruginosa in acute/chronic infection.	[62]
	P. aeruginosa	Identification of CDI genes in P. aeruginosa genomes.	[63]
	P. aeruginosa	CDI systems have a toxic effect on mammalian cell culture and increase the virulence of P. aeruginosa strains in the mouse bacteremia model.	[64]
Acinetobacter	A. baumannii, A. nosocomialis	Identification of functioning CDI systems.	[65]
	Acinetobacter spp.	Identification of >40 variants of cdi loci within the genus Acinetobacter	[67]
	A. baylyi strain ADP1	Both variants of CDI systems discovered play no roles in biofilm formation or adhesion to epithelial cells.	[66]
	A. baumannii strain DSM30011	Identification of two types of CDI toxins. The functioning of CDI systems represses biofilm formation and adhesion to the host cells.	[68]
	Neisseria meningitidis	The crystal structure of the CdiI immunity protein.	[60]
	Enterobacter cloacae	CdiA-CTECL/immunity protein complex.	[70]
	Xenorhabdus doucetiae	Identification of the cdiBCAI locus in the genomes of Xenorhabdus and Photorhabdus luminescens.	[71]