Improved Diagnostic Accuracy of Periprosthetic Breast Infection: Novel Application of the Alpha-Defensin 1 Biomarker
Marten N. Basta1, Paul Y. Liu, MD FACS1, Daniel Kwan, MD1, Karl H. Breuing, MD FACS1, Rachel Sullivan, MD1, Chris C. Jehle, MD1, Jonathan L. Bass, MD1, Brian C. Drolet, MD2, Scott Schmidt, MD1.
1Brown University & Rhode Island Hospital, Providence, RI, USA, 2Vanderbilt University School of Medicine, Nashville, TN, USA.
Implant-based breast reconstruction comprises 75% of all breast reconstructions today. Prompt, accurate diagnosis of breast implant infection is critical to minimizing patient morbidity. The current standard of care, bacterial culture, is falsely negative in 25-30% of untreated patients and substantially more patients receiving antibiotics. A critical need exists for better testing modalities that remain cost-effective. Alpha defensin-1 (AD-1), an antimicrobial peptide released from neutrophils in response to local pathogen invasion, serves as a marker for infection. With sensitivity/specificity of 97% & 96%, it has replaced bacterial culture as the preferred diagnostic modality for orthopedic periprosthetic infection. If AD-1 behaves similarly in periprosthetic breast infections, it may substantially alter practice patterns throughout plastic and reconstructive surgery, with rapid and cheap diagnostic confirmation within 24 hours. We evaluate and compare the diagnostic performance of AD-1 to bacterial culture in suspected periprosthetic breast infection.
An IRB-approved prospective study including all adults with prior prosthetic breast reconstruction (expander or implant) and suspected periprosthetic infection requiring operative washout was conducted. Patients missing gram stain and culture data were excluded. Demographics, operative history, prosthetic characteristics, and antibiotic exposure were collected. Implant pocket fluid was sent for gram stain, bacterial culture, AD-1 assay, and surgical pathology. Based upon average sample AD-1 and C-Reactive Protein (CRP) levels, the AD-1 assay reports presence/absence of infection. Sample lactate, human neutrophil elastase, and cell differentials were also collected. Summary statistics and student's T-test or Fisher tests of association were performed (p<0.05=significant).
RESULTS: 10 breasts with suspected periprosthetic infection met criteria and were included, 7 of which were acutely infected with purulent pocket fluid. Gram stain correctly identified 1 of 7 infections (accuracy-40%) while culture correctly identified 6 of 7 infections (accuracy-90%). AD-1, however, identified all 7 infections (accuracy-100%). AD-1 sensitivity was significantly better than gram stain (100% vs. 14.3%, p=0.02) and more sensitive than culture (100% vs. 85.7%), though the difference was insignificant (p=1.0). Infected breasts averaged higher levels of inflammatory markers (CRP: 15.8 mg/dL vs. 2.9 mg/dL, p=0.08), (lactate: 122 mg/dL vs. 74 mg/dL, p=0.09), both trending towards significance.
This prospective study demonstrates the utility of AD-1 in diagnosing periprosthetic breast infection. Combining AD-1 with adjunctive inflammatory markers may allow more accurate and prompt detection of implant infection in order to reduce morbidity and reconstructive failures.
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