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Published on: December 3, 2017
Clinical Analysis of Propionibacterium acnes Infection After Total Knee Arthroplasty
Scott R Nodzo1, Geoffrey H Westrich1, Michael W Henry2
1Department of Orthopedics, Hospital for Special Surgery, New York, New York.
Background:
Propionibacterium acnes is a common cause of upper extremity arthroplasty infection and usually presents in an indolent subacute fashion. It is not well described how total knee arthroplasty (TKA) patients infected with P acnes present.
Methods:
We retrospectively compared patients undergoing revision TKA for infection from P acnes and methicillin-sensitive Staphylococcal aureus (MSSA) in our institutional infection database. Patients were classified as having a periprosthetic joint infection based on the Musculoskeletal Infection Society criteria and were excluded if they had a polymicrobial culture. Patient demographics, preoperative laboratory values, microbiology data, and synovial fluid white blood cell (WBC) counts were analyzed.
Results:
Sixteen patients with a P acnes and 30 with an MSSA TKA periprosthetic joint infection were identified. Median erythrocyte sedimentation rate was significantly higher in the MSSA group compared to the P acnes group (56.0 mm/h; interquartile range [IQR], 44.3-72.9 vs 23.0 mm/h; IQR, 18.5-52.0; respectively, P = .03) as were C-reactive protein levels (5.9 mg/dL; IQR, 3.7-26.9 vs 2.0 mg/dL; IQR, 0.5-14.0; respectively, P = .04). WBC count, synovial fluid WBC, and percentage of synovial polymorphonuclear cells were similar between groups. Mean time to culture was 8.3 ± 2.0 days in the P acnes group and 1.8 ± 0.8 days in the MSSA group.
Conclusion:
P acnes TKA infections are associated with more acute inflammatory symptoms than typically appreciated, and long hold anaerobic cultures up to 14 days are necessary to accurately identify this organism as the causative agent of TKA periprosthetic infection.
Insights
Propionibacterium acnes causes knee replacement infections that present more acutely than previously thought. Long anaerobic cultures up to 14 days are essential for diagnosing P. acnes total knee arthroplasty (TKA) periprosthetic joint infections.
Area of Science:
- Orthopedics
- Infectious Diseases
- Microbiology
Background:
- Propionibacterium acnes (P. acnes) is a known cause of upper extremity arthroplasty infections, often presenting indolently.
- The clinical presentation of P. acnes in total knee arthroplasty (TKA) periprosthetic joint infections (PJIs) is not well-characterized.
Purpose of the Study:
- To compare the presentation and characteristics of TKA PJIs caused by P. acnes versus methicillin-sensitive Staphylococcus aureus (MSSA).
Main Methods:
- Retrospective comparison of TKA revision patients with P. acnes or MSSA infection.
- Infection classification based on Musculoskeletal Infection Society criteria; exclusion of polymicrobial cultures.
- Analysis of patient demographics, laboratory values, microbiology, and synovial fluid white blood cell (WBC) counts.
Main Results:
- Sixteen P. acnes and 30 MSSA TKA PJIs were identified.
- MSSA group showed significantly higher erythrocyte sedimentation rate and C-reactive protein levels compared to the P. acnes group.
- Synovial fluid WBC counts and differential were similar; mean time to culture was longer for P. acnes (8.3 days) than MSSA (1.8 days).
Conclusions:
- P. acnes TKA infections can present with more acute inflammatory symptoms than typically expected.
- Extended anaerobic cultures (up to 14 days) are crucial for the accurate diagnosis of P. acnes TKA PJIs.
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