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Published on: March 3, 2023
Polymicrobial infections reduce the cure rate in prosthetic joint infections: outcome analysis with two-stage
Matthias D Wimmer1, Max J Friedrich2, Thomas M Randau2
1Department of Orthopaedics and Trauma Surgery, University Hospital Bonn, Bonn, Germany. wimmer@uni-bonn.de.
Purpose:
Prosthetic joint infections (PJI) are a serious and challenging complication after total joint arthroplasty. According to the literature, most PJI are monomicrobial infections caused by gram-positive cocci. The number of polymicrobial PJI might be underrepresented in the literature and only limited data are available regarding the outcome of polymicrobial PJI. Our hypothesis was that polymicrobial PJI are associated with a reduced cure rate compared with monomicrobial PJI.
Methods:
Routine clinical data were collected and analysed retrospectively as anonymised, aggregated data. A total of 77 consecutive patients with 77 confirmed PJI and proven infectious organism of the hip and knee joint treated within a two-stage exchange concept and a follow-up ≥ two years were investigated. Detection of the infectious organism was based on multiple microbiological cultures taken intra-operatively. Superficial wound swabs or swabs from sinus tracts were not taken into account. Data were grouped into polymicrobial and monomicrobial PJI. The main outcome variable was "definitively free of infection after two years" as published. Second, we considered several variables as potential confounders or as risk factors.
Results:
A total of 42 men and 35 women with 46 infected total hip arthroplasties and 31 infected total knee arthroplasties were evaluated. In 37 (46.6 %) of our 77 patients a polymicrobial PJI could be detected. We found a significant association between polymicrobial PJI and the outcome parameter definitively free of infection after two years with an odds ratio (OR) of 0.3 [95 % confidence interval (CI) 0.1-1.0]. The rate of patients graded as definitively free of infection after two years was 67.6 % for polymicrobial infections vs. 87.5 % for monomicrobial infections. The American Society of Anesthesiologists (ASA) score (OR 0.4, 95 % CI 0.2-1.0, p = 0.062) was identified as a borderline significant covariable.
Conclusions:
Our data suggest that polymicrobial PJI might be underrepresented in the current literature. Additionally, the presence of multiple infectious organisms is associated with a reduced rate after two years with 67.6 vs 87.5 % for monomicrobial infections. Special attention and extra care should be considered for these patients.
Insights
Polymicrobial prosthetic joint infections (PJI) are often underdiagnosed and linked to lower cure rates compared to monomicrobial PJI. This study highlights the need for increased awareness and specialized care for patients with polymicrobial PJI.
Area of Science:
- Orthopedics
- Infectious Diseases
- Microbiology
Background:
- Prosthetic joint infections (PJI) are a significant complication following total joint arthroplasty.
- Most PJIs are believed to be monomicrobial, typically caused by gram-positive cocci.
- Polymicrobial PJIs may be underrepresented in existing literature, with limited data on their outcomes.
Purpose of the Study:
- To investigate the hypothesis that polymicrobial PJIs are associated with a reduced cure rate compared to monomicrobial PJIs.
- To analyze the outcomes of polymicrobial versus monomicrobial PJIs in patients undergoing two-stage exchange arthroplasty.
Main Methods:
- Retrospective analysis of routine clinical data from 77 patients with confirmed hip or knee PJI.
- Infectious organisms were identified using intra-operative microbiological cultures; superficial swabs were excluded.
- Patients were categorized into polymicrobial and monomicrobial groups, with a primary outcome of being definitively infection-free after two years.
Main Results:
- Polymicrobial PJI was detected in 46.6% (37/77) of patients.
- A significant association was found between polymicrobial PJI and a reduced rate of being definitively infection-free after two years (67.6% vs. 87.5% for monomicrobial PJI; OR 0.3).
- The American Society of Anesthesiologists (ASA) score was a borderline significant covariable.
Conclusions:
- Polymicrobial PJIs may be underrepresented in the literature.
- The presence of multiple organisms in PJI is associated with a lower cure rate at two years.
- Patients with polymicrobial PJI require special attention and tailored management strategies.
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