Remission after treatment of osteoarticular infections due to Pseudomonas aeruginosa versus Staphylococcus aureus: a case-controlled study

Abstract

Purpose Osteoarticular infections due to methicillinsusceptible Staphylococcus aureus (MSSA) or its methicillin-resistant variant (MRSA) are feared due to treatment failures. According to clinical experience, Pseudomonas aeruginosa may reveal less long-term remission than S. aureus. Methods A case-controlled study comparing outcomes of osteoarticular infections due to P. aeruginosa vs S. aureus was performed at Geneva University Hospitals. Results A total of 111 S. aureus (including 37 MRSA) and 20 P. aeruginosa osteoarticular infections were analysed in 131 patients: arthroplasties (n=38), fracture fixation devices (n=56), native joint arthritis (n=7) and osteomyelitis without implant (n=30). The median active follow-up time was 4 years. The patients underwent a median number of two surgical interventions for P. aeruginosa infections compared to two for S. aureus (two for MRSA), while the median duration of antibiotic treatment was 87 days for P. aeruginosa and 46 days for S. aureus infections (58 days for MRSA) (all p>0.05). Overall, Pseudomonas-infected patients tended towards a lower remission rate than those infected with S. aureus (12/20 vs 88/111; p=0.06). This was similar when P. aeruginosa was compared with MRSA alone (12/20 vs 30/37; p=0.08). In multivariate logistic regression analyses adjusting for case mix, odds ratios (OR) for remission were as follows: P. aeruginosa vs S. aureus [OR 0.4, 95% confidence interval (CI) 0.1-1.2], number of surgical interventions (OR 0.6, 95% CI 0.5-1.0) and duration of antibiotic treatment (OR 1.0, 95% CI 1.0-1.0). Conclusions Despite a similar number of surgical interventions and longer antibiotic treatment, osteoarticular infections due to P. aeruginosa tended towards a lower remission rate than infections due to S. aureus in general or MRSA in particular.

Increased risk of joint failure in hip prostheses infected with Staphylococcus aureus treated with debridement, antibiotics and implant retention compared to Streptococcus

“…Hence, our conclusion is invalid for mixed infections or other pathogens that are potentially difficult to eradicate such as Pseudomonas spp. [20,21]. Finally, all of the Genevian patients, in both populations, had mobile parts of their prostheses changed, while this information was inconsistently available in the literature.…”

Remission rate of implant-related infections following revision surgery after fractures

“…Theoretically, the Gram-negative rod P. aeruginosa is known to be particularly difficult to eradicate from osteoarticular and prosthetic joint tissue due to its extended biofilm-producing capacities, its natural resistance to a variety of antimicrobial agents and development of rapid resistance even during ongoing therapy. In the literature, osteoarticular infections due to P. aeruginosa regularly yield higher failure rates as compared to Gram-positive microorganisms, even if the difference is not always statistically significant [18][19][20].…”

“…A pathogen was identified in 135 (97 %) cases. Staphylococcus aureus was the most frequent organism (n =73, 52 %, of which 15 were resistant to methicillin), followed by coagulase-negative staphylococci (20), streptococci (7) and 19 Gram-negative rods, of which seven were Pseudomonas aeruginosa. Polymicrobial infection occurred in 24 episodes (17 %).…”

“…The infected implants involved plates (n =75, 54 %), nails (n =24, 17 %), wires (20), screws (10), cerclage cables or wires (3), hip screws (4) or material for spondylodesis (3). Twelve plates revealed one additional material such as screws or wires.…”

Optimal diagnosis, prevention, and management of periprosthetic joint infection

“…Even for antibiotic-resistant microorganisms, such as Pseudomonas aeruginosa and MRSA, that are associated with higher failure rates, there is no evidence that prolonging antibiotic therapy would decrease the failure rate. 67,68 Strictly based on expert opinion, PJI antibiotics are usually initially administered intravenously for 1-2 weeks followed by oral therapy for 3 months if the prosthesis is retained, or 6-week oral therapy in the case of prosthesis removal. 69 Following this treatment, antibiotics should be stopped, even in the presence of elevated CRP or other inflammatory parameters, as prolonging antibiotic treatment does not change the risk of recurrent PJI, which is approximately 10%-25%.…”