In these conditions, the naturally occurring largely commensal bacterium Propionibacterium acnes can cause inflammation, leading to inflammatory lesions ( papules, infected pustules, or nodules ) in the dermis around the microcomedo or comedone, which results in redness and may result in scarring or hyperpigmentation.

They are believed to work in at least 4 different ways, including: normalising shedding into the pore to prevent blockage, killing Propionibacterium acnes, anti-inflammatory effects, hormonal manipulation.

A 2007 microbiology article reporting the first genome sequencing of a Propionibacterium acnes bacteriophage ( PA6 ) said this " should greatly enhance the development of a potential bacteriophage therapy to treat acne and, therefore, overcome the significant problems associated with long-term antibiotic therapy and bacterial resistance.

Staphylococcus epidermidis and certain coryneforms such as Propionibacterium acnes are dominant.

Propionibacterium acnes can be found in bronchoalveolar lavage of approximately 70 % patients and is associated with disease activity ; however, it can be also found in 23 % of controls.

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.

Propionibacterium 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.

cs: Propionibacterium acnes

es: Propionibacterium acnes

fr: Propionibacterium acnes

it: Propionibacterium acnes

pl: Propionibacterium acnes

pt: Propionibacterium acnes

tr: Propionibacterium acnes

It was found that some of the visible violet light present in sunlight ( in the range 415 – 430 nm ) activates a porphyrin ( Coproporphyrin III ) in Propionibacterium acnes which damages and ultimately kills the bacteria by releasing singlet oxygen.

( Eradication of Propionibacterium acnes by its endogenic porphyrins after illumination with high intensity blue light.

Pathogens may also play a role in causing, perpetuating, or simply taking advantage of this phenomenon, such as virulent sub-strains of Propionibacterium acnes and irregular migration of Staphylococcus epidermidis from the outer surface of the skin into the follicle, where commensal strains of P. acnes exclusively habitate.

The rationale for their use is that Propionibacterium acnes, a bacterium known for its role in acne, has been isolated from bone biopsies of SAPHO patients.

Preliminary research also indicates S. epidermidis is universally found inside affected acne vulgaris pores, where Propionibacterium acnes is normally the sole resident.

Few examples include: Propionibacterium sp., which are normal skin flora, have been responsible for infective endocarditis sometimes leading to deaths due to the indolent course of this abscess producing infection.

Furthermore, Propionibacterium species have been found in ventriculostomy insertion sites, and areas subcutaneous to suture sites in patients who have undergone craniotomy.

Three types of bacteria are used in the production of Emmentaler: Streptococcus thermophilus, Lactobacillus, and Propionibacterium freudenreichii.

Propionibacterium is a genus of bacteria named for their unique metabolism: They are able to synthesize propionic acid by using unusual transcarboxylase enzymes.

Members of the genus Propionibacterium are widely used in the production of vitamin B12, tetrapyrrole compounds, and propionic acid as well as in probiotic and cheese industries.

The strain Propionibacterium freudenreichii subsp.

It can also be caused by Propionibacterium propionicus, and the condition is likely to be polymicrobial aerobic anaerobic infection.

These genera differ in their host range: The species in the Plectrovirus genus infect hosts of the class Mollicutes while those of the genus Inovirus infect species of Enterobacteriaceae, Pseudomonadaceae, Spirillaceae, Xanthomonadaceae, Clostridium and Propionibacterium.

Regardless, there are specific clonal sub-strains of P. acnes associated with normal skin health and others with long-term acne problems.

In vitro, resistance of P. acnes to commonly used antibiotics has been increasing, as well.

It works against the " P. acnes " bacterium, and normally causes just dryness of the skin, slight redness, and occasional peeling when side-effects occur.

With increasing resistance of P. acnes worldwide, they are becoming less effective.

The mechanism appears to be that a porphyrin ( Coproporphyrin III ) produced within P. acnes generates free radicals when irradiated by 420 nm and shorter wavelengths of light.

In addition, basic science and clinical work by dermatologists Yoram Harth and Alan Shalita and others have produced evidence that intense blue / violet light ( 405 – 425 nanometer ) can decrease the number of inflammatory acne lesion by 60 – 70 % in four weeks of therapy, in particular, when the P. acnes is pretreated with delta-aminolevulinic acid ( ALA ), which increases the production of porphyrins.

* Tea tree oil ( melaleuca oil ) has been used with some success, where it is comparable to benzoyl peroxide but without excessive drying, kills P. acnes, and has been shown to be an effective anti-inflammatory in skin infections.

Electron micrographs of siphovirus from P. acnes.

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.

The cellular damage, metabolic byproducts and bacterial debris produced by the rapid growth of P. acnes in follicles can trigger inflammation.

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.

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.

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.