Implants are increasingly used to substitute missing structure or function in the human body. Despite the improved design, biocompatibility and functionality, implants also carry a significant risk of infection. Implant-associated infections are one of the most feared and difficult to treat complications, causing high morbidity, and considerable mortality and consuming substantial health care cost.
There are more than 2 million implant insertions (knee, hip, breast, cardiac devices) per year in the USA alone (similar number in the EU), with infection rates varying from 1% to 40%, depending on the surgical site.
Implant-associated infections are difficult to detect and treat due to the presence of biofilms on the implant surface. The antimicrobial susceptibility is significantly reduced in biofilms, causing chronic and persistent infections.
Delayed and low-grade infections, such as those induced by P. acnes, are especially difficult to detect and treat, because the acute infection symptoms are absent and the infection is diagnosed too late, after a significant amount of biofilm is formed. P. acnes-infected implants have to be exchanged in a two-stage process with careful removal of all foreign material combined with antibiotic treatment. This procedure is cumbersome, time-consuming and often functional recovery is delayed or suboptimal.
Treatment of implant infections generates medical cost of up to €100,000 per patient and long rehabilitation times and off-work periods. Consequently, there is a high medical need for a prophylactic vaccine to prevent implant-associated infections.