Implant-associated infections are difficult to detect and treat due to the formation of biofilms, which make bacteria much more resistant to antibiotics. Propionibacterium acnes and Staphylococcus epidermidis are the most frequently isolated organisms from these infections, in addition to Staphylococcus aureus. However, unlike S. aureus-induced infections, these two organisms do not induce acute infection symptoms such as pain and fever, instead, these symptoms appear much later, sometimes many weeks or months after surgery. This makes them very difficult to treat, because by the time physicians detect the infection, a significant amount of biofilm is formed and antibiotics are much less effective against them. Weakened or slower to develop an additional immune response helps these bacteria to establish a strong biofilm community, which is much more difficult to eradicate.
Standard treatment procedure for infected implants is exchange 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. Therefore, current treatment options are limited and cause great discomfort for patients.
Staphylococcus epidermidis. Coloured Scanning Electron Micrograph (SEM) of colonies of the bacteria Staphylococcus epidermidis. It is a Gram-positive cocci (spherically-shaped) bacteria that has a tendency to form grape-like clusters, as seen here. Staphylococcus epidermidis is usually non-pathogenic and found all over the human skin, and on many mucous surfaces. It colonizes plastic, resulting in bacteraemia around catheters and surgical implants (such as heart valves). Such infections often do not respond to antibiotic treatment, and implants may have to be removed.