Propionibacterium acnes
Chris Brannan

Propionibacterium acnes is the most common gram-positive, non-spore forming, anaerobic rod encountered in clinical specimens. P. acnes typically grows as an obligate anaerobe, however, some strains are aerotolerant, but still show better growth as an anaerobe. It has the ability to produce propionic acid, as its name suggests. It also has the ability to produce catalase along with indole, nitrate, or both indole and nitrate. Propionibacterium resembles Corynebacterium in morphology and arrangement, but is non-toxigenic.

P. acnes is the causative agent of acne vulgaris (pimples). It is a common resident of the pilosebaceous glands of the human skin. The bacteria release lipases to digest a surplus of the skin oil, sebum, that has been produced. The combination of digestive products (fatty acids) and bacterial antigens stimulates an intense local inflammation that bursts the hair follicle. Then, a lesion forms on the surface of the skin in the form of a pustule (Whitehead). Since acne is caused in part from an infection, it can be suppressed with topical and oral antibiotics such as clindamycin, erythromycin, or tetracycline. Some other forms of therapy include chemicals that enhance skin removal (i.e. benzoyl peroxide) or slow the production of sebum (Retin A and Accutane).

P. acnes is highly susceptible to various beta-lactam antimicrobial agents such as piperacillin and ampicillin-sulbactain. This bacteria is also very sensitive to penicillin G. Other infections for which P. ances has been implicated include corneal ulcers, heart valves and prosthetic devices, and central nervous system shunts. A rare heart disease known as Propionibacterium acnes endocarditis has been discovered in a prosthetic valve infected with P. acnes. The valve was also complicated by multiple mycotic aneurysms.


*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.


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