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Year : 2007  |  Volume : 73  |  Issue : 4  |  Page : 270

A possible role for human follicle mites in skin's defense against bacteria

Department of Dermatology, Shiraz University of Medical Sciences, Shiraz, Iran

Correspondence Address:
M R Namazi
P.O. Box 71955-687, Shiraz
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0378-6323.33646

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How to cite this article:
Namazi M R. A possible role for human follicle mites in skin's defense against bacteria. Indian J Dermatol Venereol Leprol 2007;73:270

How to cite this URL:
Namazi M R. A possible role for human follicle mites in skin's defense against bacteria. Indian J Dermatol Venereol Leprol [serial online] 2007 [cited 2020 Jun 1];73:270. Available from: http://www.ijdvl.com/text.asp?2007/73/4/270/33646


Free fatty acids constitute 10-30% of the human skin surface fat but occur in only small amounts in the skin lipids of most other animals. [1] This difference has been tentatively attributed to the rather unique bacterial flora of humans, in particular Propionibacterium acnes and its lipase action on sebum triglycerides. Analysis of pure sebum from isolated human sebaceous glands showed the presence of triglycerides but not free fatty acids, monoglycerides or diglycerides. [2] It has been suggested that unsaturated fatty acids, particularly oleic acid, play an important role in elimination of Streptococcus pyogenes and S taphylococcus aureus from human skin. [3]

Herein, I would like to suggest that not only the unique bacterial flora of humans, but also the follicle mites could play an important role in the skin's defence against pathogenic bacteria. Demodex folliculorum , the follicle mite, is an obligate parasite of the human pilosebaceous follicles. A morphologically distinct species, D. brevis, occupies the sebaceous and  Meibomian gland More Detailss. [4] Follicle mites show a predilection for areas of high sebum production and are most numerous on the forehead, cheeks, nose and nasolabial folds but they are also found on the scalp, in the external ear, in eyelash follicles and meibomian glands and on the upper chest and nipples. They have also been discovered on the penis, mons veneris, buttocks and in ectopic sebaceous glands in the buccal mucosa. Most infested follicles contain 2-6 mites but occasionally they are much more numerous. Mites have been isolated from humans of all ages except neonates. [5]

Importantly, like bacterial flora found on human skin, follicle mites have been shown to contain immunoreactive lipase, [6] which can produce free fatty acids from sebum triglycerides. Hence I suggest that follicle mites could play a role in the human skin's defence against pathogenic bacteria, particularly against Staphylococcus aureus and Streptococcus pyogenes.

  References Top

1.Nicolaides N. Human skin surface lipids-origin, composition and possible function. In : Montagna W, Ellis RA, Silver AF, editors. Advances in biology of skin, Vol 4, Sebaceous glands. Pergamon: Oxford; 1963. p. 167-86.  Back to cited text no. 1      
2.Kellum RE. Human sebaceous gland lipids: Analysis by thin-layer chromatography. Arch Dermatol 1967;95:218-20.  Back to cited text no. 2  [PUBMED]    
3.Richetts CR, Squire JR, Topley E. Human skin lipids with particular reference to the self-sterilizing power of the skin. Clin Sci 1951;10:89-96.  Back to cited text no. 3      
4.Hirst S. Studies in Acari, No 1. The Genus Demodex, Owen. British Museum (Natural History): London; 1919.  Back to cited text no. 4      
5.Franklin CD, Underwood JC. Demodex infestation of oral mucosal sebaceous glands. Oral Surg Oral Med Oral Pathol 1986;61:80-2.  Back to cited text no. 5  [PUBMED]    
6.Jimenez-Acosta F, Planas L, Penneys N. Demodex mites contain immunoreactive lipase. Arch Dermatol 1989;125:1436-7.  Back to cited text no. 6  [PUBMED]    


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