This image shows fluorescently labelled human rotator cuff cells infected with P acnes. The P acnes bacteria are detected with a specific monoclonal antibody, and are red in this image. The rotator cuff cells have their nuclei stained with DAPI, which fluoresces blue, and the cytoplasm of the cells are detected with an antibody to actin filaments and fluoresce green. This image was prepared by Mr. Boyang Qiu, an undergraduate student in Dr. David O’Gorman’s laboratory.
The American Shoulder and Elbow Surgeons association has awarded a team of London researchers the 2017 Charles S. Neer Award for Clinical Science, one of the most prestigious awards in the areas of shoulder and elbow surgical research in North America.
The award recognizes the scientists’ development of the PCR-RFLP (polymerase chain reaction restriction fragment length polymorphism) assay, a test that can accurately identify Propionibacterium acnes (P acnes) infection of the shoulder within 24 hours. Current methods take an average of six or more days, and are prone to sample contamination and false-positive results.
“We are incredibly honoured to receive this award,” says Dr. David O’Gorman, Lawson scientist, Co-Director of Molecular and Cellular Research at the Roth McFarlane Hand and Upper Limb Centre (HULC) at St. Joseph’s Health Care London, and senior author of the publication. “We believe it illustrates the high quality of research being done at Lawson and marks the beginning of another clinically relevant research program at HULC.”
P acnes is a type of bacteria typically found deep in the hair follicles and sebaceous pores of the skin. A P acnes infection of the shoulder is a common and serious complication that occurs after arthroplasty (surgery to replace a damaged joint, most commonly with artificial material). It can cause pain in the shoulder joint and often loosens the implant. In most cases, the patient requires additional surgery to remove the infection and replace the implant.
It can be difficult to diagnose a P acnes infection as it often presents without symptoms that would be characteristic of an infection, such as pain, skin reddening or wound drainage. The prevalence of P acnes in the deeper layers of the skin also increases the chance of sample contamination and false-positive results making it hard to isolate and identify in a pathology lab.
Currently P acnes infection is identified by administering a tissue swab for anaerobic culture, which takes an average of six or more days but could take up to three weeks. This technique also carries substantial risk of contamination from the adjacent skin and other sites where P acnes is present.
The PCR-RFLP assay can identify P acnes in tissue from a shoulder biopsy within a 24-hour period. The extremely sensitive technology also has the ability to detect fewer than ten P acnes cells in the sample, which may decrease the false-positive rate in cultures caused by swab contamination.
“The accuracy of this test and the shorter period of time needed for identification can help with treatment decision making, targeted antibiotic therapy, and monitoring to minimize implant failure and revision surgery,” explains Dr. O’Gorman, who is also an Assistant Professor in the Departments of Surgery and Biochemistry at Western University’s Schulich School of Medicine & Dentistry. “We hope that the test can be further developed into a ‘point of case’ assay that can detect P acnes in tissue samples in real time while the patient is undergoing shoulder surgery.”
Since the PCR and RFLP mapping used for the assay are techniques routinely performed in many clinical microbiology and pathology labs, the test would be a cost-efficient approach not restricted to highly specialized research labs.
Other scientists who were part of the study include Dr. George Athwal and Dr. Kenneth Faber, HULC orthopaedic surgeons, Lawson scientists and Schulich professors; Ana Pena Diaz, research technician for the HULC Molecular and Cellular Biology Research Lab; and Scott Holmes, a medical student and Schulich Research Opportunities Program participant who was primarily responsible for designing and optimizing the assay.
Both Dr. O’Gorman and Dr. Faber are also members of Western’s Bone and Joint Institute.
“A rapid method for detecting Propionibacterium acnes in surgical biopsy specimens from the shoulder” was published in the Journal of Shoulder and Elbow Surgery (JSES).