Background: In late pregnancy, the oily secretion sebum together with the shed peridermal cells makes up a lipid rich substance, called vernix caseosa. Vernix acts as a biofilm, covering the surface of newborn babies. Until now, it's function has mainly been thought to minimize excessive water loss. We have identified a number of antimicrobial components in vernix, such as antimicrobial peptides that act by disrupting cytoplasmic membranes, indicating an active protection against microbes by vernix. Antimicrobial peptides are of various origins and are considered to be significant in the first line of host defense among diverse groups of organisms, ranging from plants to mammals. The aim of this study was to identify novel antimicrobial components of vernix, e.g. peptides and lipids, that are active against group B streptococcus (GBS) and E. coli, and to study the relationship between surface protection of neonates and the antimicrobial activity found in vernix.
Methods: Vernix samples were collected from 82 newborns. Superficial skin cultures were analyzed from all neonates to evaluate bacterial colonization. Extracts from vernix samples were prepared and each extract was screened for activity against GBS and E. coli. Both active and inactive extracts were analysed by HPLC. Purification of the active extracts were carried out in order to identify the active component. Component of apparently pure HPLC fraction was characterized by MS/MS analysis.
Results: Fifteen groups of bacteria were found to colonize the surface of the 82 babies. One was not colonized by bacteria, 26 were colonized with one group of bacteria, 33 were colonized with two groups, 19 were colonized with three groups, and three were colonized with four groups. Sixtyfive extracts showed activity against GBS, and 21 extracts against E. coli. The quantity of the active component in each extract was shown to vary according to the activity of the extracts. One HPLC fraction was active against both GBS and E. Coli. The active component in this fraction has been purified and identified as a lipid.
Conclusion: Our results reveal an antimicrobial component found in vernix that is active against both Gram positive and Gram negative bacteria. In order to find a potential relationship between antimicrobial components of vernix and the colonization data further investigation is needed. This includes identification of more antimicrobial components, measurements of their expression levels, and studies of their synergistic interaction.
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Bergsson, G., Tollin, M., Lengqvist, J. et al. 30 Antimicrobial Components of Vernix Caseosa. Pediatr Res 56, 469 (2004). https://doi.org/10.1203/00006450-200409000-00053