Joint replacement surgery is a common approach to treating severe joint pain or dysfunction that does not respond to less invasive therapy. Successful surgery offers improved quality of life with decreased pain and improved mobility. However, this treatment also comes with the risk of joint infection, and treatment of such an infection may not be straightforward.
New antibiotics and new combinations of antibiotics are necessary to deal with the antibiotic resistance that bacteria develop over time.
Lab Imitation of Joint Replacement
A study to mimic a joint replacement followed by infection has been carried out. In the animal lab, Wistar rats were implanted with a rod into the thigh bone. The rod was made of sterile steel and was infected with a bacterial suspension before being implanted. Two different kinds of bacteria suspension were tested.
Antibiotics Treatments Attempted
Treatment with antibiotics started seven days after the surgery. The antibiotics that were tested individually include linezolid, vancomycin, rifampin, and cotrimoxazole. A few antibiotic combinations were also tested: 1. rifampin + linezolid, 2. rifampin + vancomycin, and 3. rifampin + cotrimoxazole. After 23 days, the implants were removed, and the bacterial counts of the implant and surrounding tissues examined.
Joint Infection Under Control
In this study, rifampin is the only antibiotic to significantly reduce the bacterial infection on its own. However, it is already known that monotherapy using rifampin is not a good option. Previous studies found frequent development of resistance to treatment when only rifampin is used. An effective treatment needs to also prevent these resistance mechanisms from forming or evolving.
As it turns out, the combination antibiotic treatments used in this study were also found to be effective. And in addition, the combination treatment significantly reduced the development of resistance.
A Real Concern
Infection after joint replacement surgery is rare for a first-time surgery. However, if repeated surgeries are required, the risk of infection is significant. And since replaced joints typically last only 10-25 years, many people eventually require a second and third or more replacement surgeries. Therefore, it is important to determine an effective method of treatment for this type of infection.
Goetz J, Keyssner V, Hanses F, et al. Animal experimental investigation on the efficacy of antibiotic therapy with linezolid, vancomycin, cotrimoxazole, and rifampin in treatment of periprosthetic knee joint infections by MSRA. Bone Joint Res. 2022 Mar;11(3):143-151. doi:10.1302/2046-3758. PMID: 35227086