Table 1.

Antimicrobial effects of chitosan preparations: a summary of in vitro studies.

Chitosan preparations	Microorganisms	Major results/conclusions	Ref.
Chitin and chitosan powder	Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus saprophyticus	Effective antimicrobial effect	[10]
Chitosan solution	Staphylococcus aureus	Chitosan led to multiple changes in the bacterial gene expression; binding of chitosan to teichoic acid led to death of bacteria	[11]
Chitosan and chitosan oligomer	Gram-positive and Gram-negative bacteria	Chitosan generally showed stronger bactericidal effects with Gram-positive bacteria than Gram-negative bacteria	[12]
N-carboxybutyl chitosan	298 strains Gram-positive bacteria, Gram-negative bacteria and Candida spp.	Particularly active against Candida and Gram-positive bacteria; no bactericidal activity was observed with streptococci and enterococci	[13]
Solutions of chitosan hydrochloride, carboxymethyl chitosan, chitosan oligosaccharide, and N-acetyl-D-glucosamine	Candida albicans, Candida krusei and Candida glabrata	Antifungal activity decreases with declining molecular mass and increasing masking of the protonated amino groups with functional groups	[14]
Thiazolidinone derivatives of chitosan	E. coli, Shigella dysenteriae, P. aeruginosa and Bacillus subtilis	Better antimicrobial activity than chitosan’s Schiff’s bases	[15]
Chitosan hydrolysate	Bacillus cereus, E. coli, S. aureus, P. aeruginosa, Salmonella enterica serovar Typhi and Saccharomyces cerevisiae.	Strong activity at 100 ppm against many pathogens and yeast species	[16]
Chitosan film loaded with thyme oil	E. coli, Klebsiella pneumoniae, P. aeruginosa and S. aureus	Chitosan films with 1.2% (v/v) showed antimicrobial activity on all microorganisms tested	[17]
Chitosan hydrochloride, 5-methyl-pyrrolidinone chitosan	S. aureus, Staphylococcus epidermidis, P. aeruginosa, C. albicans and Aspergillus niger	Antimicrobial activity against bacteria and C. albicans is shown by the dressing	[18]
Chitosan incorporated with polyphosphate and silver	S. aureus and P. aeruginosa	Complete kill of P. aeruginosa and a >99.99% kill of S. aureus	[19]
Arginine-functionalized chitosan	Pseudomonas fluorescens and E. coli	At the concentration of 5000 mg/l, 6%- and 30%-substituted chitosan-arginine killed 2.7 logs and 4.5 logs of P. fluorescens, and 4.8 logs and 4.6 logs of E. coli in 4 h, respectively	[7]
Chitosan hydrogel	P. aeruginosa, E. coli, S. aureus and Fusarium solani	Excellent antimicrobial/antifungal activities	[6]