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Propionibacterium acnes is the relatively slow-growing, typically aerotolerant anaerobic, Gram-positive bacterium (rod) 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 can generate enzymes for degrading skin and proteins that may be immunogenic (activating the immune system).
This bacterium is largely commensal and part of the skin flora present on most healthy adult humans' skin. It is usually just barely detectable on the skin of healthy preadolescents. It lives primarily on, among other things, fatty acids in sebum secreted by sebaceous glands in the follicles. 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 
P. acnes bacteria live deep within follicles and pores, away from the surface of the skin. In these follicles, P. acnes bacteria use sebum, cellular debris and metabolic byproducts from the surrounding skin tissue as their primary sources of energy and nutrients. Elevated production of sebum by hyperactive sebaceous glands (sebaceous hyperplasia) or blockage of the follicle can cause P. acnes bacteria to grow and multiply.
P. acnes bacteria secrete many proteins, including several digestive enzymes. These enzymes are involved in the digestion of sebum and the acquisition of other nutrients. They can also destabilize the layers of cells that form the walls of the follicle. The cellular damage, metabolic byproducts and bacterial debris produced by the rapid growth of P. acnes in follicles can trigger inflammation. This inflammation can lead to the symptoms associated with some common skin disorders, such as folliculitis and acne vulgaris.
The damage caused by P. acnes and the associated inflammation make the affected tissue more susceptible to colonization by opportunistic bacteria, such as Staphylococcus aureus. Preliminary research shows healthy pores are only colonized by P. acnes, while unhealthy ones universally include the nonpore-resident Staphylococcus epidermidis, amongst other bacterial contaminants. Whether this is a root causality, just opportunistic and a side effect, or a more complex pathological duality between P. acnes and this particular Staphylococcus species is not known.
P. acnes has also been found in corneal ulcers, and is a common cause of chronic endophthalmitis following cataract surgery. Rarely, it infects heart valves leading to endocarditis, and infections of joints (septic arthritis) have been reported. Furthermore, Propionibacterium species have been found in ventriculostomy insertion sites, and areas subcutaneous to suture sites in patients who have undergone craniotomy. It is a common contaminant in blood and cerebrospinal fluid cultures.
P. acnes has been found in herniated discs. The propionic acid which it secretes creates micro-fractures of the surrounding bone. These micro-fractures are sensitive and it has been found that antibiotics have been helpful in resolving this type of low back pain.
P. acnes can be found in bronchoalveolar lavage of approximately 70% of patients with sarcoidosis and is associated with disease activity, but it can be also found in 23% of controls. The subspecies of P. acnes that cause these infections of otherwise sterile tissues (prior to medical procedures), however, are the same subspecies found on the skin of individuals who do not have acne-prone skin, so are likely local contaminants. Moderate to severe acne vulgaris appears to be more often associated with virulent strains.
P. acnes is an opportunistic pathogen, causing a range of postoperative and device-related infections e.g.,surgery, post-neurosurgical infection, joint prostheses, shunts and prosthetic heart valves. P. acnes may play a role in other conditions, including inflammation of the prostate leading to cancer, SAPHO (Synovitis, Acne, Pustulosis, Hyperostosis, Osteitis) syndrome, sarcoidosis and sciatica.
Antimicrobial susceptibility 
P. acnes bacteria are susceptible to a wide range of antimicrobial molecules, from both pharmaceutical and natural sources. Antibiotics are commonly used to treat infections caused by P. acnes. Acne vulgaris is the disease most commonly associated with P. acnes infection. The antibiotics most frequently used to treat acne vulgaris are: erythromycin, clindamycin, doxycycline and minocycline. Several other families of antibiotics are also active against P. acnes bacteria, including quinolones, cephalosporins, pleuromutilins, penicillins and sulfonamides.
The emergence of antibiotic-resistant P. acnes bacteria represents a growing problem worldwide. The problem is especially pronounced in North America and Europe. The antibiotic families that P. acnes are most likely to acquire resistance to are the macrolides (e.g. erythromycin and azithromycin), lincosamides (e.g. clindamycin) and tetracyclines (e.g. doxycycline and minocycline).
However, P. acnes bacteria are susceptible to many types of antimicrobial chemicals found in over-the-counter antibacterial products, including benzoyl peroxide, triclosan, PCMX, and chlorhexidine gluconate.
Several naturally occurring molecules and compounds are toxic to P. acnes bacteria. Some essential oils such as rosemary, tea tree oil, clove oil  and citrus oils contain antibacterial chemicals.
The elements silver, sulfur, and copper have also been demonstrated to be toxic towards many bacteria, including P. acnes. Natural honey has also been shown to have some antibacterial properties that may be active against P. acnes.
P. acnes glows orange when exposed to Wood's light, possibly due to the presence of endogenous porphyrins. The bacterium is killed by ultraviolet light. P. acnes is also especially sensitive to light in the 405–420 nanometer (near the ultraviolet) range due to an endogenic porphyrin–coporphyrin III. A total irradiance of 320 J/cm² is found to inactivate this bacterium 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, and in practice was not significantly better than the light treatment alone.
- Dali, P.; Giugliano, E. R.; Vellozzi, E. M.; Smith, M. A. (2001). "Susceptibilities of Propionibacterium acnes Ophthalmic Isolates to Moxifloxacin". Antimicrobial Agents and Chemotherapy 45 (10): 2969–70. doi:10.1128/AAC.45.10.2969-2970.2001. PMC 90767. PMID 11583007.
- Bruggemann, H.; Henne, A; Hoster, F; Liesegang, H; Wiezer, A; Strittmatter, A; Hujer, S; Dürre, P et al. (2004). "The Complete Genome Sequence of Propionibacterium Acnes, a Commensal of Human Skin". Science 305 (5684): 671–3. doi:10.1126/science.1100330. PMID 15286373.
- Perry, Alexandra; Lambert, Peter (2011). "Propionibacterium acnes: Infection beyond the skin". Expert Review of Anti-infective Therapy 9 (12): 1149–56. doi:10.1586/eri.11.137. PMID 22114965.
- Makrantonaki, et al. (2011). "An update on the role of the sebaceous gland in the pathogenesis of acne.". Dermatoendocrinology 22 (5): 360–6. doi:10.1016/j.clindermatol.2004.03.004. PMID 15556719.
- Holland, et al. (2010). "Proteomic identification of secreted proteins of Propionibacterium acnes". BMC Microbiology 10: 230. doi:10.1186/1471-2180-10-230. PMC 3224659. PMID 20799957.
- Kim. (2005). "Review of the innate immune response in acne vulgaris: activation of Toll-like receptor 2 in acne triggers inflammatory cytokine responses". Dermatology 211 (3): 191–2. doi:10.1159/000087010. PMID 16205062.
- Zouboulis. (2004). "Acne and sebaceous gland function". Clinical Dermatology 22 (5): 360–6. doi:10.1016/j.clindermatol.2004.03.004. PMID 15556719.
- "Understanding Acne - News in Health, January 2010". Newsinhealth.nih.gov. Retrieved 2012-06-14.
- "What is Propionibacterium acnes?". ScienceOfAcne.com. Retrieved 2012-08-07.
- Bek-Thomsen, et al. (2008). "Acne is Not Associated with Yet-Uncultured Bacteria". Journal of Clinical Microbiology 20 (3): 197–203. PMID 14620162.
- Albert, et al. (2013). "Antibiotic treatment in patients with chronic low back pain and vertebral bone edema (Modic type 1 changes): a double-blind randomized clinical controlled trial of efficacy". European Spine Journal 22 (4): 697–707. doi:10.1007/s00586-013-2675-y. PMID 23404353.
- Hiramatsu, J; Kataoka, M; Nakata, Y; Okazaki, K; Tada, S; Tanimoto, M; Eishi, Y (2003). "Propionibacterium acnes DNA detected in bronchoalveolar lavage cells from patients with sarcoidosis". Sarcoidosis, vasculitis, and diffuse lung diseases 20 (3): 197–203. PMID 14620162.
- Inoue, Y; Suga, M (2008). "Granulomatous diseases and pathogenic microorganism". Kekkaku 83 (2): 115–30. PMID 18326339.
- Lomholt, Hans B.; Kilian, Mogens (2010). "Population Genetic Analysis of Propionibacterium acnes Identifies a Subpopulation and Epidemic Clones Associated with Acne". In Bereswill, Stefan. PLoS ONE 5 (8): e12277. doi:10.1371/journal.pone.0012277. PMC 2924382. PMID 20808860.
- Haidar R., Najjar M., Boghossian A.D., Tabbarah Z., "Propionibacterium acnes causing delayed postoperative spine infection: Review." Scandinavian Journal of Infectious Diseases. 42 (6-7) (pp 405-411), 2010
- Nisbet, M. Briggs, S. Ellis-Pegler, R. Thomas, M. Holland, D. "Propionibacterium acnes: an under-appreciated cause of post-neurosurgical infection" Journal of Antimicrobial Chemotherapy. 60(5). NOV 2007. 1097-1103.1103..
- Fassi Fehri L. Mak TN. Laube B. Brinkmann V. Ogilvie LA. Mollenkopf H. Lein M. Schmidt T. Meyer TF. Bruggemann H. Ijmm.,"Prevalence of Propionibacterium acnes in diseased prostates and its inflammatory and transforming activity on prostate epithelial cells." International Journal of Medical Microbiology. 301(1) 69-78, 2011 Jan.
- Perry A., Lambert P. " Propionibacterium acnes: Infection beyond the skin." Expert Review of Anti-Infective Therapy. 9 (12) (pp 1149-1156), 2011
- "Prescription Medications for Treating Acne". Skincarephysicians.com. 2007-02-16. Retrieved 2012-06-14.
- Strauss, et al. (2007). "Guidelines of care for acne vulgaris management". Journal of the American Academy of Dermatology 56 (4): 651–63. doi:10.1016/j.jaad.2006.08.048. PMID 17276540.
- Hoeffler, et al. (1976). "Antimicrobial Susceptibility of Propionibacterium acnes and related microbial species.". Antimicrobial Agents and Chemotherapy 10 (3): 387–94. PMC 429758. PMID 984781.
- Wang, et al. (1977). "Susceptibility of Propionibacterium acnes to seventeen antibiotics.". Antimicrobial Agents and Chemotherapy 11 (1): 171–3. PMC 351938. PMID 836012.
- "Antibiotic Susceptibility of Propionibacterium acnes". ScienceOfAcne.com. 2011-07-15. Retrieved 2012-08-08.
- Tzellos, et al. (2011). "Treating acne with antibiotic-resistant bacterial colonization.". Expert Opinions in Pharmacotherapy 12 (8): 1233–47. doi:10.1517/14656566.2011.553192. PMID 21355786.
- Ross, et al. (2001). "Phenotypic and genotypic characterization of antibiotic-resistant Propionibacterium acnes isolated from acne patients attending dermatology clinics in Europe, the U.S.A., Japan and Australia.". British Journal of Dermatology 144 (2): 339–46. PMID 11251569.
- Ross, et al. (2003). "Antibiotic-resistant acne: lessons from Europe.". British Journal of Dermatology 148 (3): 467–78. PMID 12653738.
- Coates, et al. (2002). "Prevalence of antibiotic-resistant propionibacteria on the skin of acne patients: 10-year surveillance data and snapshot distribution study.". British Journal of Dermatology 146 (5): 840–8. PMID 12000382.
- Leyden, JJ; Wortzman, M; Baldwin, EK (2008). "Antibiotic-resistant Propionibacterium acnes suppressed by a benzoyl peroxide cleanser 6%". Cutis 82 (6): 417–21. PMID 19181031.
- Fu, Yujie ; Zu, Yuangang ; Chen, Liyan [Author]; Efferth, Thomas Liang, Huili ; Liu, Zhiguo Liu, Wei "Investigation of antibacterial activity of rosemary essential oil against propionibacterium acnes with atomic force microscopy"Planta Medica. 73(12). OCT 2007. 1275-1280.
- Raman, et al. (1995). "Antimicrobial effects of tea-tree oil and its major components on Staphylococcus aureus, Staph. epidermidis and Propionibacterium acnes.". Letters in Applied Microbiology 21 (4): 242–5. PMID 7576514.
- Fu, Yujie; Chen, L; Zu, Y; Liu, Z; Liu, X; Liu, Y; Yao, L; Efferth, T (2009). "The Antibacterial Activity of Clove Essential Oil Against Propionibacterium acnes and Its Mechanism of Action". Archives of Dermatology 145 (1): 86–8. doi:10.1001/archdermatol.2008.549. PMID 19153353.
- Lang, Gudrun Buchbauer, Gerhard "A review on recent research results (2008–2010) on essential oils as antimicrobials and antifungals. A review." Flavour and Fragrance Journal 271 2012
- Baik, Jong Seok [Author]; Kim, Sang-Suk [Author]; Lee, Jung-A [Author]; Oh, Tae-Heon [Author]; Kim, Ji-Young [Author]; Lee, Nam Ho [Author]; Hyun, Chang-Gu "Chemical composition and biological activities of essential oils extracted from Korean endemic citrus species" Journal of Microbiology & Biotechnology. 18(1). JAN 2008. 74-79.
- Bayston, et al. (2010). "In vitro antimicrobial activity of silver-processed catheters for neurosurgery". Journal of Antimicrobial Chemotherapy 65 (2): 258–65. doi:10.1093/jac/dkp420. PMID 19942617.
- Libenson, et al. (1953). "Antibacterial effect of elemental sulfur.". Journal of Infectious Diseases 93 (1): 28–35. PMID 13069766.
- McLean, et al. (1993). "Antibacterial activity of multilayer silver-copper surface films on catheter material.". Canadian Journal of Microbiology 39 (9): 895–9. PMID 8242490.
- Albietz, et al. (2006). "Effect of antibacterial honey on the ocular flora in tear deficiency and meibomian gland disease.". Cornea 25 (9): 1012–9. doi:10.1097/01.ico.0000225716.85382.7b. PMID 17133045.
- Papageorgiou, P.; Katsambas, A.; Chu, A. (2000). "Phototherapy with blue (415 nm) and red (660 nm) light in the treatment of acne vulgaris". British Journal of Dermatology 142 (5): 973–8. doi:10.1046/j.1365-2133.2000.03481.x. PMID 10809858.