Propionibacterium acne is a slow growing, anaerobic gram
positive bacteria. acne is skin bacteria responsible for shoulder infections
and it usually has a subtle subclinical presentation. They can be rod shaped or
branched usually found in the skin pores. Propionibacterium acnes may colonize
in the axilla especially in males. There is difficulty in obtaining positive
cultures from standard labs. Propionibacterium acnes are generally
nonpathogenic but can cause numbers of infection such as acne vulgaris. The
Propionibacterium acne infection is one of the most common causes of shoulder
infection such as rotator cuff infection. In fact, some people think that it is
the most common organism isolated after rotator cuff surgery. The interesting thing about Propionibacterium
acne is that it grows very slowly. Most of the standard labs will read the
culture up to 5 days, but the Propionibacterium acne can grow up to 14 days. If
the lab states that there is no growth, this could mean that you didn’t give it
enough time. The patient may have this infection and the infection may continue
despite the fact that the culture came back negative. It game back before the
growth of the organisms. The standard
labs will not keep the culture for two weeks unless you tell them to keep the
culture. Allow up to two weeks for the
culture to grow and to identify this organism. Ask the lab to hold the culture
for a longer time if you strongly suspect the infection in the shoulder. This
organism colonizes the shoulder at an increased rate. Mini open cuff repair after arthroscopic
surgery may have increased risk of that infection. A second prep and drape of
the surgical field was suggested to reduce the incidence of infection. Positive culture was found also in revision
shoulder arthroplasty. Staphylococcus epidermidis loses the prosthesis,
especially in the hip or the knee. P-acne however, loves the prosthesis in the
shoulder. The clinical presentation is insidious and nonspecific. The traditional signs of infection are
usually lacking: fever, erythema, severe pain. Blood work is usually not
consistently elevated. It is a slow growing bacteria and the cultures take from
one to three weeks to become positive. This creates a diagnostic challenge. The
initial culture is usually negative. The lab does not usually hold the cultures
unless instructed with personal communication with the appropriate personnel.
If you suspect infection, ask the lab to hold the culture for at least 2 weeks. P-acne is a common cause of indolent shoulder
infection and shoulder implant failure. Infection of the shoulder with P-acne
should be considered as a cause of persistent unexplained shoulder pain.
Treatment includes obtaining fluid from aspiration, or obtain a tissue sample
(multiple tissue samples are better), keep the culture for two weeks,
debridement, IV antibiotics (resistance of the bacteria to antibiotics is a
challenge). Any prosthesis may need to be removed. In summary, the Propionibacterium acne
infection is an emerging clinical entity. The harm goes beyond the skin and
should not be considered a contaminant. It is becoming an orthopedic pathogen
and not just a dermatology pathogen. It
is probably resistant to the standard broad spectrum antibiotics. The clinician
should be aware that this bacteria loves to infect the shoulder.
