Bactericidal activity of cerumen

Abstract

Freshly collected cerumen (dry form) suspended at a concentration of 3% in glycerol-sodium bicarbonate buffer showed bactericidal activity against some strains of bacteria tested. This suspension reduced the viability of Haemophilus influenzae, Escherichia coli K-12, and Serratia marcescens by more than 99%, whereas the viability of two Pseudomonas aeruginosa isolates, E. coli K-1, Streptococcus, and two Staphylococcus aureus isolates of human origin was reduced by 30 to 80%. The results support the hypothesis that cerumen functions to kill certain foreign organisms which enter the ear canal.Cerumen, commonly known as earwax, is secreted by both ceruminous and sebaceous glands. Two distinct forms of human cerumen, dry and wet, are associated with race and controlled by two autosomal alleles (10). The dry allele is predominant in Mongoloid populations of Asia and in American Indians, whereas the wet allele is found predominantly in Caucasian and Negro populations (1, 10). Earwax has been found to contain amino acids, fatty acids, neurostearic acid, cerotic acid, cholesterol, triglyceride, hexone bases, lysozyme, immunoglobulin, glycopeptide, copper, and other components, although differences in composition between the cerumen types have been described (6,7,9,15).The function of cerumen in protecting the ear against invasion of microorganisms has long been a subject of controversy. It has been suggested that cerumen is unable to prevent infection and that the rich nutrients of earwax support luxuriant growth of bacteria and fungi (3,8,13,14). On the other hand, it has been suggested that cerumen might have antimicrobial activity, although little evidence has been presented to support this contention (5, 9). Burtenshaw (2) extracted cerumen with either saline or an alcohol-ether solvent and showed that the saline extract promoted the growth of streptococci somewhat, whereas the alcohol-ether extract was inhibitory. However, the concentration of cerumen in the alcohol-ether extract used by this author was not specified. In this communication we will describe a potent antibacterial activity of cerumen suspended in buffer against certain strains of common bacteria which are often encountered in humans.Pooled cerumen was collected with a sterile earwax hook from 12 healthy individuals aged from 5 to 42, including males and females, and kept in a sterile bottle at 4°C. All cerumen belonged to the typical dry form, which appeared flaky or granular and yellowish white. The pooled cerumen was mixed well, weighed, and suspended in buffer (5% NaHCO3, pH 8.2, containing 30% glycerol) at a concentration of 3.5% (wt/vol). The cerumen-buffer mixture was homogenized by repeated passage through a series of needles ranging from 19 to 23 gauge. This procedure broke the cerumen into fine particles distributed evenly in buffer and resulted in a milky suspension. Cerumen suspensions at concentrations over 3.5% were unsatisfactory because all the cerumen remained in big particles even after prolonged homogenization. The cerumen was ster...

Palmitoleic Acid Isomer (C16:1Δ6) in Human Skin Sebum Is Effective against Gram-Positive Bacteria

“…It has been know since the 1940s that sebum lipids impart a self-disinfecting activity to the skin surface [1,2], and it has been accepted that free fatty acids are responsible for this property [2][3][4]. However, relatively little direct evidence has been published to support this claim or identify which fatty acids may be responsible.…”

Local immune response in the skin of the external auditory meatus: An immunohistochemical study

“…Earlier studies suggested that the rich nutrients of cerumen support the growth of bacteria and fungi (Creed and Negus, 1926;Perry and Nichols, 1956;Singer et al, 1952;Syverton et al, 1946). On the other hand, cerumen suspended in buffer showed bactericidal activity against certain strains of common bacteria which are often encountered in humans (Chai and Chai, 1980). The reason of controversy could be that all studies have been made on cerumen in different forms (dry-form or/and wet-form) or using various extractive methods.…”

Human antimicrobial proteins in ear wax

“…The argumentation against a bactericidal activity are based on the consideration that the rich nutrients of ear wax enable bacteria and fungi to grow [57][58][59][60][61]. On the other hand there are several reports describing an antimicrobial effect of ear wax with an effect against a wide range of bacteria including Haemophilus influenzae, Staphylococcus aureus, Escherichia coli and fungi [61][62][63][64][65][66]. Stoeckelhuber et al reported the detection of the antimicrobial proteins ß-defensin-1, ß-defensin-2, cathelicidin, lysozyme, lactoferrin, MUC1 and the secretory component of IgA in the ceruminous glandular cells by histochemical analysis [67].…”