A new study reveals that the type of surgery performed to treat these infections plays a more significant role in outcomes than other factors.
When patients receive prosthetic joints, there is always a chance of infection. Although only 1% to 2% of prosthetic joints may become infected, with the significant increase in the number of arthroplasties being performed worldwide in the last 10 years, the number of infections is likely to rise.
The cause of these infections historically has been more likely to be gram-positive bacteria than gram-negative bacteria; however, the medical community has seen an increase in the latter lately. As it is no simple task to treat prosthetic joint infections, and as gram-negative bacteria are notoriously resistant to many drugs, this development is concerning.
To determine if the type of surgery performed in an effort to clear prosthetic joint infections makes a difference in the outcome, a group of investigators based in Budapest and Athens performed a retrospective analysis of data on 131 patients that had been collected by the European Study Group for Implant Associated Infections between 2000 and 2015. The patients were followed for 24 months after having surgery and antibiotics for prosthetic joint infections.
The type of surgery was divided into 2 categories: debridement, antibiotics with implant retention (DAIR) and non-DAIR, which encompassed any other type of procedure during which the implant was removed.
In addition to determining whether the type of surgery mattered when it came to success or failure, the investigators wanted to know if the type of antibiotic resistance affected the outcome.
Patients were classified as having either multidrug-resistant infections or extensively drug-resistant infections. The study team also sought to determine whether the type of antibiotic administered to patients made a difference.
A clear finding was that, overall, the study subjects who received non-DAIR treatment had higher success rates after 24 months than those who had DAIR surgery. Almost 77% of patients in the non-DAIR group saw their infections completely resolve within that time period versus nearly 48% of the latter group. This held true whether the subjects developed infections soon after arthroplasty or later on.
Another discovery was that patients with multidrug-resistant infections had more successful outcomes than those with extensively drug-resistant, but the type of surgery performed still mattered more than the type of resistance—non-DAIR techniques worked better in nearly 80% of those with multidrug-resistant infections and 60% of those with extensively drug-resistant.
Finally, the type of antibiotic administered did not matter as much as the type of surgery when it came to successful outcomes, although it was noted that colistin clearly underperformed in multidrug-resistant infection cases.
The authors allowed that although non-DAIR is likely the best choice in most situations, this is not an absolute.
“Our data have a major strength: they strongly suggest that the type of surgery is independently associated with outcome in patients with prosthetic joint infections by multidrug-resistant / extensively drug-resistant gram-negative bacteria,” the authors wrote in a report. “DAIR had failed even in early infections. However, we must take into account that the curative surgery is often scheduled before awareness of multidrug-resistant / extensively drug-resistant gram-negative bacterial infections, as most cultures are taken intra-operatively. DAIR is a recommended procedure for surgical treatment of prosthetic joint infections, under certain conditions.”
These conditions include the infection occurring early (within the first 4 weeks), the prosthesis remaining stable, and the infection responsive to antibiotics. This may mean an infection caused by the pathogen S aureus, for instance, can be successfully treated with DAIR while 1 caused by MRSA will likely fail to clear with the same treatment, as happened in nearly three-quarters of MRSA-caused prosthetic joint infections in another report.
Ultimately, physicians must analyze each situation in order to make the best choices.
“Our data suggest that in multidrug-resistant / extensively drug-resistant gram-negative bacterial infections, an early aggressive surgical approach with prosthesis removal in combination with all available options of antimicrobial treatment is the preferred treatment option,” the investigators wrote. “However, we cannot neglect that in more than 40% of cases overall, DAIR was successful. These results further indicate the need of individualization of therapy.”