Synergic antistaphylococcal properties of lactoferrin and lysozyme

Abstract

Staphylococcus epidermidis colonises a wide range of implanted prosthetic devices, but rarely contact lenses -despite a similarity in material composition. A conceivable explanation for this anomaly is the action of the tear defences, including the constitutive proteins lactoferrin and lysozyme. Therefore this study investigated the effect of lactoferrin, lysozyme and serum on the growth of S. epidermidis isolates in artificial tear fluid. Whether supplemented with serum alone or serum with either apolactoferrin or lysozyme, this medium induced a similar, strain-variable effect. However, simultaneous addition of these proteins induced a greater bactericidal or bacteristatic effect. Of those strains killed by the concerted action of apolactoferrin and lysozyme, the absence of serum led to a further increase in the bactericidal effect, whereas strains displaying bacteriostasis were unaffected by serum. Iron saturation of lactoferrin reversed the antimicrobial synergy of apolactoferrin and lysozyme. These results show synergy between lactoferrin and lysozyme which is dependent on the iron limitation of lactoferrin. As a bactericidal mechanism, this synergy is augmented by serum, but bacteriostasis remains unaffected by serum supplemention. Thus, the combination of lysozyme and lactoferrin may partly explain the low level of contact lens colonisation by S. epidermidis in vivo.

PspA Protects Streptococcus pneumoniae from Killing by Apolactoferrin, and Antibody to PspA Enhances Killing of Pneumococci by Apolactoferrin

“…ALF, but not HLF, can be bacteriostatic or bactericidal (5,40,63). The bacteriostatic activity of ALF is due in part to its iron chelating ability, which can deplete iron and restrict bacterial growth (48).…”

Session 1: Feeding and infant development Breast-feeding and immune function

“…Both lactoferrin and its fragments are bactericidal for many Grampositive and Gram-negative bacteria. This effect does not seem to be related to the binding of Fe, which is needed by most bacteria; rather, it is the result of a destabilizing effect on the outer cell membrane of bacteria, making them more sensitive to lysozyme, which is also present in the milk (Ellison, 1994;Leitch & Willcox, 1998). Lactoferrin promotes growth of the strictly anaerobic Bifidobacteria, but it also cleaves colonization factors on the potential pathogen Haemophilus influenzae and hinders the mucosal adherence of enteropathogenic E. coli (Hendrixson et al 2003;Ochoa et al 2003).…”

Lactoferrin: a review

“…The binding of lactoferrin to these receptors induces cell-death in Gram-negative bacteria due to a disruption in the cell wall. The subsequent release of lipopolysacharide (LPS) leads to impaired permeability and a higher sensitivity to lysozyme and other antimicrobial agents (Arnold et al, 1977;Yamauchi et al, 1993;Leitch and Willcox, 1998). LPS can be disposed of even without the direct contact of lactoferrin with the cell surface (Rossi et al, 2002).…”