Annals of Indian Academy of Otorhinolaryngology Head and Neck Surgery

ORIGINAL ARTICLE
Year
: 2019  |  Volume : 3  |  Issue : 1  |  Page : 13--16

Human cerumen and its antimicrobial properties: Study at a tertiary care teaching hospital of Eastern India


Santosh Kumar Swain1, Nishtha Anand1, Mahesh Chandra Sahu2,  
1 Department of Otorhinolaryngology, IMS and SUM Hospital, Siksha “O” Anusandhan University (Deemed to be), Bhubaneswar, Odisha, India
2 Division of Microbiology, ICMR-NIOH, Ahmedbad, Gujurat, India

Correspondence Address:
Prof. Santosh Kumar Swain
Department of Otorhinolaryngology, IMS and SUM Hospital, Siksha “O” Anusandhan University (Deemed to be), Bhubaneswar - 751 003, Odisha
India

Abstract

Aim: This study aimed to find out the antibacterial and antifungal properties of the human cerumen. Materials and Methods: This is a prospective study conducted at the department of otorhinolaryngology and medical research laboratory of a tertiary care teaching hospital of Eastern India between December 2016 and November 2018 for assessing the antibacterial and antifungal properties of the human cerumen. Cerumen was collected from 102 healthy persons by using sterile Jobson Horne Probe. Sterile samples were taken for the study. Results: Out of the 102 samples, 68 sterile samples were considered for the study. At a dilution of 1 in 105, there was complete inhibition of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa in all the samples. In this study, cerumen inhibited the bacteria in the order of E. coli > S. aureus > P. aeruginosa > Haemophilus influenzae > Aspergillus niger > Candida albicans. Conclusion: Cerumen or earwax of the human being has antibacterial and antifungal properties. Other than antibacterial and antifungal properties, it also protects the eardrum by acting as a physical barrier. Hence, cerumen cleaning is not advisable unless it is causing symptoms such as otalgia or hearing loss.



How to cite this article:
Swain SK, Anand N, Sahu MC. Human cerumen and its antimicrobial properties: Study at a tertiary care teaching hospital of Eastern India.Ann Indian Acad Otorhinolaryngol Head Neck Surg 2019;3:13-16


How to cite this URL:
Swain SK, Anand N, Sahu MC. Human cerumen and its antimicrobial properties: Study at a tertiary care teaching hospital of Eastern India. Ann Indian Acad Otorhinolaryngol Head Neck Surg [serial online] 2019 [cited 2019 Oct 20 ];3:13-16
Available from: http://www.aiaohns.in/text.asp?2019/3/1/13/265134


Full Text



 Introduction



Cerumen or earwax is formed by sebaceous glands, ceruminous glands, and apocrine glands, which are present at the outer one-third of the human external auditory canal and create an acidic coat which aids in the prevention of infections of the external auditory canal.[1] Lack of earwax may cause infection as it serves an antimicrobial property by physical protection of the ear canal, creating a low pH and inhospitable atmosphere for pathogens and antimicrobial substance such as lysozyme; hence, its absence leads to ear canal-susceptible ear canal infections.[2] Earwax or cerumen is a naturally occurring substance in the external auditory canal which cleans, protects, and lubricates the ear canal. Cerumen or earwax is a common cause for conductive hearing loss and sometimes presents with tinnitus, irritation, otalgia, and vertigo.[3] In most of the cases, there are no symptoms at all. Cerumen is formed from glandular secretions from the outer one-third of the external auditory canal and exfoliated squamous epithelium, which migrates out of the ear canal due to jaw movement.[4] Impacted wax occurs due to failure of self-cleaning mechanism in the ear canal. The function of the cerumen/earwax against the microorganisms invading the ear has long been a subject of controversy. This study aims to evaluate the antibiotic and antifungal effects of human cerumen on pathogens such as Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Haemophilus influenzae, Candida albicans, and Aspergillus niger.

 Materials and Methods



This is a prospective study conducted at the department of otorhinolaryngology and medical research laboratory of a tertiary care teaching hospital of Eastern India between December 2016 and November 2018. This study obtained clearance from the Institutional Ethics Committee. Wax [Figure 1] sample was collected from 102 normal and healthy individuals by the help of Jobson Horne Probe. The wax was made emulsified with the help of 30% glycerol with 5% sodium bicarbonate, which converted into 3.5% suspension of wax (weight/volume). This wax suspension was stored at 20°C till use in microbiological testing. The suspension of the cerumen was placed on nutrient agar plate for culture of any bacteria and incubated at 37°C overnight for suspecting any commensal bacteria of the external auditory canal. The wax samples which did not reveal any growth were kept for testing. Bacterial strains such as P. aeruginosa (MTCC1688), S. aureus (MTCC7443), H. influenzae (MTCC3826), and E. coli (MTCC443) were tested, and fungal strains such as C. albicans and A. niger were also tested. All the bacteria and fungus were identified with previous methods.[5],[6],[7],[8],[9],[10] The four bacterial and two fungal strains were cultured on nutrient agar and Sabouraud's dextrose agar, respectively, and incubated at 37°C for 24 h for getting fresh culture. The isolated colony of each culture was shifted to 10-ml nutrient broth and incubated for at least 6 h at 37°C, and the inoculum was adjusted to 0.5 McF (i.e.,1.5 × 108 colony-forming unit/ml). Then, tenfold dilution ranging from 1 in 101 to 1 in 105 was prepared by mixing 100 μl of the prepared inoculum to a tube containing 900 μl of 3.5% wax suspension. Different dilutions of inoculums were incubated at 37°C for 15–18 h. After incubation, 10 μl of the suspension of each dilution was taken into a blood agar plate, was streaked, was incubated for 24 h at 37°C, and was observed for any colonies/growth. Any colony or growth was checked after incubation, and the results were documented.{Figure 1}

 Results



In this study, the samples of cerumen were collected with labeling of 1–102. A total of 58 samples were sterile which were selected for the study, whereas 44 samples were unsterile and rejected from the study, i.e., not considered for the study. It was observed from the data that sterile human cerumen can inhibit P. aeruginosa, S. aureus, E. coli, H. influenza, and C. albicans in decreasing order. The growth control revealed adequate growth of the test strains, and negative control revealed no growth showing the validity of the test conditions. [Table 1] summarizes the number of samples where growth was inhibited.{Table 1}

 Discussion



In day-to-day clinical practice, otolaryngologists and pediatricians often confront with earwax or cerumen. Cerumen is present in 10% of all the pediatric age groups and in up to 57% of the elderly.[11] Cerumen is also called earwax which is secreted from both ceruminous and sebaceous glands. Cerumen or earwax is a yellow-brownish waxy substance which protects the skin of the ear canal from water and infection. It prevents infection by trapping the microorganisms, sweat, dirts, dead skin cells, oil, and hair. The outer ear canal is lined with hairs called cilia which push the offending particle toward the ear opening where the wax can be washed off. There are two different forms of the human cerumen, and these are dry and wet which are often associated with race and decided by two autosomal alleles. The wet earwax is light or dark brown and sticky, possessing a high concentration of lipid and pigment granules. The dry allele is most often seen in Mongoloid people of Asia and in American Indians, whereas the wet variety is common in Caucasian and Negro populations. Cerumen consists of amino acids, neurostearic acid, cerotic acid, triglyceride, cholesterol, hexone bases, lysozyme, immunoglobulin (Ig), glycopeptides, copper, and others.[12] The dry earwax is gray or tan and brittle and possesses less lipid and pigment granules. The dry earwax contains approximately 20% of lipid in comparison to 50% in the wet earwax.[13] Cerumen or earwax is formed from a combination of glandular secretion of the lateral one-third of the external auditory canal and exfoliated squamous epithelium, which migrates of the external auditory canal by self-cleaning mechanism during jaw movement.[14] Cerumen also lubricates and cleans the ear canal, trapping the dust and repelling the water.[15] Cerumen also protects the middle ear against various bacteria and fungi.[16] Hence, cerumen plays an important role biologically and clinically for host defense although it is relatively weak. Cerumen or earwax creates an acidic barrier in the external auditory canal, which prevents infection.[1] There are many contradictory reports for the antibacterial activity of cerumen. The antibacterial property of cerumen is based on high nutrients of cerumen which enable bacteria and fungi to grow, then killed by its acidic environment.[17] Cerumen is slightly acidic in nature, which discourages the growth of bacteria and fungus in the moist and dark environment of the external auditory canal. It is almost impossible to avoid infection at the ear canal without the presence of cerumen.[18] An enzyme called lysozyme is present in the cerumen; hence the absence of earwax makes the ear canal vulnerable to infection. It is expected that, if cerumen provides immunity, its composition should alter in response to infection and exposure to bacteria, which induce antibacterial components of the cerumen at the ear canal. However, in otitis externa, cerumen does not provide antibacterial polyunsaturated fatty acids than without any infection at the external auditory canal.[19] In this study, earwax inhibited the growth of bacteria and fungi at various concentrations. Our study demonstrated the antibacterial and antifungal properties of cerumen, which show the protective role of cerumen toward the external auditory canal. One study also proved the antibacterial property of earwax in some mammals.[20] One study showed the mycobacterial effect of earwax, which is consistent with our study.[21] In the present study, it has been demonstrated that the human earwax exhibits antibacterial and antifungal properties. But it has less antifungal than antibacteria and this may be due to some protective mechanism of the fungus which leads to lower inhibition of the fungal growth as compared to the bacterial growth. Our study agrees with one study which demonstrated the bactericidal properties of earwax on P. aeruginosa.[21] Some other studies have reported that cerumen has no bactericidal effect on P. aeruginosa.[22] In this study, cerumen inhibited the growth of E. coli; this finding is consistent with other studies,[23] whereas one study showed insignificant bactericidal effect and stated that E. coli is not a normal commensal in the external auditory canal and so may not be accepted by the immune system of the ear canal.[22] In this study, cerumen showed bactericidal activity against two strains of H. influenzae tested. H. influenzae type b is often the cause for meningitis in children, whereas noncapsular H. influenzae strains are often the cause for middle-ear infections. As cerumen is secreted in the external auditory canal, it does not often come in contact with bacteria in middle-ear infection. Immunohistochemical studies show that antibody-mediated immune reactions rather than earwax protect the ear canal from infective microorganisms. The epidermis and dermis of the skin lining the external auditory canal contain ceruminous and sebaceous glands as well as piliary follicles which are capable of activating local immunity by IgA and IgG.[24] However, it needs more studies to confirm the nature of host defense in this anatomical location. There are many controversial reports in medical literature which are explained on the basis of culture media, methodology, and virulence of microorganisms. Microorganisms such as S. aureus, P. aeruginosa, and C. albicans cause otitis externa, whereas their presence in cerumen in the external auditory canal reduces the chance of infection.[21] In this study, the study samples were kept at 20°C and then processed. This type of storage may affect the antibacterial and antifungal properties, which may affect more if tests are done immediately.

 Conclusion



Cerumen of the human has both bactericidal and fungicidal effects. Apart from being a physical barrier of cerumen in the ear canal, it also acts as antibacterial and antifungal agents. This may lead to prevention or eradication of the infections of the external ear-like otitis externa. Hence, routine wax removal of the ear canal should be discouraged unless it is impacted, leading to hearing loss or earache. The outcome of our study should be treated with caution as the number of microbial strains is limited or small. An extensive study should be conducted to reveal the bactericidal and fungicidal roles of cerumen or earwax. The different outcomes among documented literatures may be due to the fact that earwax from different persons varies in its composition and contents of inhibitory factors due to the different genetic profile of the patients.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

1Campos A, Arias A, Betancor L, Rodríguez C, Hernández AM, López Aguado D, et al. Study of common aerobic flora of human cerumen. J Laryngol Otol 1998;112:613-6.
2Bojrab DI, Bruderly T, Abdulrazzak Y. Otitis externa. Otolaryngol Clin North Am 1996;29:761-82.
3Aung T, Mulley GP. Removal of ear wax. BMJ 2002;325:27.
4Roland PS, Smith TL, Schwartz SR, Rosenfeld RM, Ballachanda B, Earll JM, et al. Clinical practice guideline: Cerumen impaction. Otolaryngol Head Neck Surg 2008;139:S1-21.
5Sahu MC, Dubey D, Rath S, Debata NK, Padhy RN. Multidrug resistance of Pseudomonas aeruginosa as known from surveillance of nosocomial and community infections in an Indian teaching hospital. J Public Health 2012;20:413-23.
6Sahu MC, Padhy RN.In vitro antibacterial potency of Butea monosperma Lam. against 12 clinically isolated multidrug resistant bacteria. Asian Pac J Trop Dis 2013;3:217-26.
7Sahu MC, Patnaik R, Padhy RN.In vitro combinational efficacy of ceftriaxone and leaf extract of Combretum albidum G. Don against multidrug-resistant Pseudomonas aeruginosa and host-toxicity testing with lymphocytes from human cord blood. J Acute Med 2014;4:26-37.
8Sahu MC, Debata NK, Padhy RN. Antibacterial activity of Argemone mexicana L. against multidrug resistant Pseudomonas aeruginosa, isolated from clinical samples. Asian Pac J Trop Biomed 2012;2:800-7.
9Sahu MC, Padhy RN. Bayesian evaluation of two conventional diagnostic methods for pathogenic fungal infections. J Acute Med 2014;4:109-19.
10Sahu MC, Swain SK, Kar SK. Genetically diversity of Pseudomonas aeruginosa isolated from chronic suppurative otitis media with respect to their antibiotic sensitivity pattern. Indian J Otolaryngol Head Neck Surg 2018. p. 1-9. [doi.org/10.1007/s12070-018-1358-8]. [In press].
11Roeser RJ, Ballachanda BB. Physiology, pathophysiology, and anthropology/epidemiology of human earcanal secretions. J Am Acad Audiol 1997;8:391-400.
12Yassin A, Mostafa MA, Moawad MK. Cerumen and its micro-chemical analysis. J Laryngol Otol 1966;80:933-8.
13Tomita H, Yamada K, Ghadami M, Ogura T, Yanai Y, Nakatomi K, et al. Mapping of the wet/dry earwax locus to the pericentromeric region of chromosome 16. Lancet 2002;359:2000-2.
14Saxby C, Williams R, Hickey S. Finding the most effective cerumenolytic. J Laryngol Otol 2013;127:1067-70.
15Shapiro J, Clarke C. Earwax woes. Harv Health Lett 2002;27:8.
16Lindsey D. It's time to stop washing out ears! Am J Emerg Med 1991;9:297.
17Campos A, Betancor L, Arias A, Rodríguez C, Hernández AM, López Aguado D, et al. Influence of human wet cerumen on the growth of common and pathogenic bacteria of the ear. J Laryngol Otol 2000;114:925-9.
18Schwaab M, Gurr A, Neumann A, Dazert S, Minovi A. Human antimicrobial proteins in ear wax. Eur J Clin Microbiol Infect Dis 2011;30:997-1004.
19Osborne JE, Baty JD. Do patients with otitis externa produce biochemically different cerumen? Clin Otolaryngol Allied Sci 1990;15:59-61.
20Sokolov VE, Ushakova NA, Chernova OF, Shubkina AB, Alimbarova LM, Barinskiĭ IF. The anti-infective properties of mammalian earwax. Izv Akad Nauk Ser Biol 1995;5:579-85.
21Lum CL, Jeyanthi S, Prepageran N, Vadivelu J, Raman R. Antibacterial and antifungal properties of human cerumen. J Laryngol Otol 2009;123:375-8.
22Pata YS, Ozturk C, Akbas Y, Gorur K, Unal M, Ozcan C. Has cerumen a protective role in recurrent external otitis? Am J Otolaryngol 2003;24:209-12.
23Stone M, Fulghum RS. Bactericidal activity of wet cerumen. Ann Otol Rhinol Laryngol 1984;93:183-6.
24Sirigu P, Perra MT, Ferreli C, Maxia C, Turno F. Local immune response in the skin of the external auditory meatus: An immunohistochemical study. Microsc Res Tech 1997;38:329-34.