Rifampin for Prosthetic Joint Infections: Lessons Learned Over 20 Years at a VA Medical Center
Background: The Minneapolis Veterans Affairs Health Care System uses debridement and implant retention (DAIR) combined with oral rifampin and a second antibiotic to treat orthopedic implant infections. However, the success rate of this approach in a veteran population is unknown.
Methods: We performed a retrospective analysis of patients who underwent DAIR with a rifampin-containing regimen for an orthopedic implant infection over the past 20 years at the Minneapolis Veterans Affairs Health Care System. The primary outcome was treatment success among participants who were treated with curative intent, defined as planned device retention without ongoing antibiotic use. Secondary outcomes were treatment harms and therapy duration. Treatment success was defined as the absence of recurrent infection or further measures to suppress infection within 1 year of completing antimicrobial therapy.
Results: A total of 78 patients (88% male) were included (median age, 65.5 years), with 50 treated with curative intent (primary analysis group). Forty-one participants (82%) in the curative intent group experienced treatment success. The success rate was higher among participants whose implant was < 2 months old vs those whose implant was ≥ 2 months old (93% vs 65%, respectively; P = .02). The 28 participants treated without curative intent had more comorbidities, higher rates of chronic infection, and older implants than those treated with curative intent.
Conclusions: Veterans with orthopedic implant infections can be successfully treated with DAIR combined with a rifampin-containing antimicrobial regimen. Success is highest for patients with a recent implant. Debridement and implant retention using regimens that include rifampin is an evidence-based strategy for managing patients with infected prosthetic hardware. Here we report that this approach is feasible in a veteran population, especially with recently implanted prosthetic material.
Forty-two participants (54%) had Staphylococcus aureus and 31 participants (40%) had coagulase-negative staphylococci infections, while 11 gram-negative organisms (14%) and 6 gram-positive anaerobic cocci (8%) infections were noted. Cutibacterium acnes and Streptococcus agalactiae were each found in 3 participants (4% of), and diphtheroids (not further identified) was found on 2 participants (3%). Candida albicans was identified in a single participant (1%), along with coagulase-negative staphylococci, and 2 participants (3%) had no identified organisms. There were multiple organisms isolated from 20 patients (26%).
Fifty participants had clear documentation in their EHR that cure of infection was the goal, meeting the criteria for the intent-to-cure group. The remaining 28 participants were placed in the without-intent-to-cure group. Success and failure rates were only measured in the intent-to-cure group, as by definition the without-intent-to-cure group patients would meet the criteria for failure (removal of prosthesis or long-term antibiotic use). The without-intent-to-cure group had a higher median age than the intent-to-cure group (69 years vs 64 years, P = .24) and a higher proportion of male participants (96% vs 80%, P = .09). The median (IQR) implant age of 11 months (1.0-50.5) in the without-intent-to-cure group was also higher than the median implant age of 1 month (0.6-22.0) in the primary group (P = .22). In the without-intent-to-cure group, 19 participants (68%) had a chronic infection, compared with 11 (22%) in the intent-to-cure group (P < .001).
The mean (SD) Charlson Comorbidity Index in the without-intent-to-cure group was 2.5 (1.3) compared with 1.9 (1.4) in the intent-to-cure group (P = .09). There was no significant difference in the type of implant or microbiology of the infecting organism between the 2 groups, although it should be noted that in the intent-to-cure group, 48 patients (96%) had Staphylococcus aureus or coagulase-negative staphylococci isolated.
The median (IQR) dosage of rifampin was 600 mg (300-900). The secondary oral antibiotics used most often were 36 fluoroquinolones (46%) followed by 20 tetracyclines (26%), 6 cephalosporins (8%), and 6 penicillins (8%). Additionally, 6 participants (8%) received IV vancomycin, and 1 participant (1%) was given an oral antifungal in addition to a fluoroquinolone because cultures revealed bacterial and fungal growth. The median (IQR) duration of antimicrobial therapy was 3 months (1.4-3.0). The mean (SD) duration of antimicrobial therapy was 3.6 (2.4) months for TKA infections and 2.4 (0.9) months for THA infections.
Clinical Outcome
Forty-one intent-to-cure group participants (82%) experienced treatment success. We further subdivided the intent-to-cure group by implant age. Participants whose implant was < 2 months old had a success rate of 93%, whereas patients whose implant was older had a success rate of 65% (P = .02).
Secondary Outcomes
The median (IQR) duration of antimicrobial treatment was 3 months (1.4-3.0) for the 38 patients with TKA-related infections and 3 months (1.4-6.0) for the 29 patients with THA infections. AEs were recorded in 24 (31%) of all study participants. Of those with AEs, the average number reported per patient was 1.6. Diarrhea, gastric upset, and nausea were each reported 7 times, accounting for 87% of all recorded AEs. Five participants reported having a rash while on antibiotics, and 2 experienced dysgeusia. One participant reported developing a yeast infection and another experienced vaginitis.
