Everything about Propionibacterium Acnes totally explained
Propionibacterium acnes is a relatively slow growing, typically
aerotolerant anaerobic gram positive bacterium that's linked to the
skin condition
acne; it can also cause chronic
blepharitis and
endophthalmitis, the latter particularly following
intraocular surgery. The
genome of the bacterium has been sequenced and a study has shown several
genes that can generate
enzymes for degrading
skin and
proteins that may be immunogenic (activate the
immune system).
This bacteria is largely
commensal and thus present on most people's skin; and lives on
fatty acids in the
sebaceous glands on
sebum secreted by
pores. It may also be found throughout the
gastrointestinal tract in humans and many other animals. It is named after its ability to generate
propionic acid.
Role in disease
When a pore is blocked this anaerobic bacteria overgrows and secretes chemicals that break down the wall of the pore, spilling bacteria such as
Staphylococcus aureus into the skin, and forming an acne lesion (
folliculitis). It has also been found in
corneal
ulcers, and on very few occasions damaging heart valves leading to
endocarditis, and infections of joints (
septic arthritis) have been reported. Furthermore, Propionibacterium have been found in
ventriculostomy insertion sites, and areas subcutaneous to
suture sites in patients that have undergone
craniotomy.
Antibiotic sensitivity
P. acnes can be killed by
benzoyl peroxide,
tetracycline group and other
antibiotics, and many
antibacterial preparations. However, tetracycline-resistant
P. acnes is now quite common.
Clindamycin is also frequently used. New facts show that P.acnes are sensitive to some
macrolides such as
Azithromycin, which has a wide spectrum of action. It is normally prescribed 500 mg by mouth, three times weekly for 4 to 6 weeks. Azithromycin exhibits post-antibiotic effect by concentrating in the
lung tissue for approximately 5 days. Indeed some antibacterial cream or ointment should be used during the therapy, giving a good local effect. Another antibiotic is
Nadifloxacin from the group of so called 4-
fluoroquinolones, such as
Ciprofloxacin,
Ofloxacin and
Levofloxacin. It has action against P. acnes and some other
microorganisms that also take part of the poly-infection.
Phage sensitivity
P. acnes has known
phages that can attack it, and these can be used to type it. In addition proposals exist to employ
lytic phages for therapeutic purposes for
acne vulgaris.
Photosensitivity
P. acnes glows when exposed to
Wood's light— believed to be due to the presence of endogenous
porphyrins. The bacteria is killed by
ultraviolet light.
P. acnes is also especially sensitive to light in the 405–420
nm (near the ultraviolet) range due to an endogenic porphyrin–coporphyrin III. A total
irradiance of 320 J/cm^2 is found to inactivate this bacteria in vitro. This fact is used in
phototherapy. Its photosensitivity can be enhanced by pretreatment with
aminolevulinic acid which boosts production of this chemical, although this causes significant side-effects in humans.
Further Information
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