The antifungal effect of lactoferrin and lysozyme on Candida krusei and Candida albicans

Lactoferrin and lysozyme (muramidase) are non-immune defence factors present in various exocrine secretions, including saliva. Previous studies have shown that both proteins, either singly or in combination, are bactericidal in nature and their combined activity is synergistic. As little is known of their interactions with Candida species, 20 oral isolates of C. krusei and 5 isolates of C. albicans were studied for their susceptibility to human apo-lactoferrin and lysozyme, either singly or in combination, using an in vitro assay system. The two species exhibited significant interspecies differences in susceptibility to lactoferrin (p < 0.05), but not for lysozyme; C. krusei being more sensitive to lactoferrin (c 1.4 times) than C. albicans. Both species revealed significant intraspecies differences in their susceptibility to lysozyme (p < 0.05), but not for lactoferrin. No synergistic antifungal activity of the two proteins on either Candida species was noted. The results imply that the variable expression of the fungicidal activity of lactoferrin and lysozyme on Candida species may modulate the oral carriage of yeasts in a complex manner.