PJI is a serious complication of joint replacements of the hip, knee, shoulder, elbow, wrist or ankle. Bacteria may infect the artificial joint (prosthesis) during or after surgery, causing infection.
Infections that affect the site of the incision (the cut made through the skin to do the procedure) may occur anywhere from a few days to up to three months following surgery. Infections of the tissue surrounding the prosthesis may occur up to two years after surgery, and can cause significant pain. Infection can also damage the new joint, requiring a second replacement.
According to the American Journal of Orthopedics, up to 2% of the hundreds of thousands of joint replacements performed every year in the U.S. become infected. This translates into thousands of infections annually.
In up to 50% of PJI cases, standard cultures fail to identify the organism causing the infection, making it difficult to determine which drug to use to treat it. This is why a MicroGenDX test for PJI is so important.
MicroGenDX tests can diagnose PJI
To treat a PJI, your doctor needs to know if the joint is infected and which organism is causing the infection. Growing microbes from your sample in a lab, also known as a culture, is often used to try to diagnose PJI infections. However, about half the time, standard cultures either come back negative even when you actually have an infection, or if they diagnose an infection, they can’t pinpoint the organism that’s actually causing it. That means your infection won’t be treated properly (some providers prescribe antibiotics but have no way of knowing if the antibiotic is targeting the right bacteria) or it won’t be treated at all.
An international consensus meeting on orthopedic infections held in 2018 states that “molecular diagnosis” should be used to isolate the organisms causing PJI. Molecular diagnosis is what the MicroGenDX OrthoKEY PJI test provides. Rather than relying on standard culture, OrthoKEY detects the DNA of all microbes in your sample along with how much of each is present. This information is used to identify the specific cause of the infection and the drugs that can best treat it. Your doctor can use a single test in the operating room (OR) or the clinic.
Medical specialties treating PJI
Prompt identification is important to prevent further complications or spread of the infection. Treatment can involve a team of experts such as an orthopedic surgeon, a wound care nurse, an infectious disease consultant, and a physical therapist.
How PJI is treated
When an infection is present, the MicroGenDX test will indicate options for antibiotics your specialist can prescribe to treat the infection in the “antimicrobials for consideration” section of the test results. In some cases, the wound (usually around the incision site) is reopened, and infected tissue is removed (a process called debridement) while leaving the new joint in place. Sometimes, all or part of the artificial joint may need to be replaced.