Bacteria in skin mites targeted as cause of rosacea
10 September 2012
The common dermatological condition called rosacea could be
triggered by bacteria in tiny mites that live in the skin, according to
research by the National University of Ireland.
Rosacea is a common dermatological condition that causes reddening
and inflammation of the skin mostly around the cheeks, nose and
chin. In severe cases skin lesions may form and lead to
Rosacea affects around 3% of the population — usually fair-skinned
females aged 30-50 and particularly those with weak immune systems.
The condition is treated with a variety of antibiotics, even though
there has never been a well-established bacterial cause.
The finding will allow more targeted, effective treatments to be
developed for sufferers, according to a review published in the
Journal of Medical Microbiology.
The mite species Demodex folliculorum is worm-like in
shape and usually lives harmlessly inside the pilosebaceous unit
which surrounds hair follicles of the face. They are normal
inhabitants of the face and increase in number with age and skin
damage — for example, following exposure to sunlight. The numbers of
Demodex mites living in the skin of rosacea patients is higher than
in normal individuals, which has previously suggested a possible
role for the mites in initiating the condition.
More recently, the bacterium Bacillus oleronius was
isolated from inside a Demodex mite and was found to produce
molecules provoking an immune reaction in rosacea patients. Other
studies have shown patients with varying types of rosacea react to
the molecules produced by this bacterium, exposing it as a likely
trigger for the condition. What's more, this bacterium is sensitive
to the antibiotics used to treat rosacea.
Dr Kevin Kavanagh who conducted the review explained, "The
bacteria live in the digestive tracts of Demodex mites found on the
face, in a mutually beneficial relationship. When the mites die, the
bacteria are released and leak into surrounding skin tissues,
triggering tissue degradation and inflammation."
"Once the numbers of mites increase, so does the number of
bacteria, making rosacea more likely to occur. Targeting these
bacteria may be a useful way of treating and preventing this
condition," said Dr Kavanagh. "Alternatively we could look at
controlling the population of Demodex mites in the face. Some
pharmaceutical companies are already developing therapies to do
this, which represents a novel way of preventing and reversing
rosacea, which can be painful and embarrassing for many people."
The potential role of Demodex folliculorum mites and bacteria in
the induction of rosacea Stanisław Jarmuda, Niamh O'Reilly, Ryszard
Żaba, Oliwia Jakubowicz, Andrzej Szkaradkiewicz and Kevin Kavanagh
Journal of Medical Microbiology DOI 10.1099/jmm.0.048090-0