Improved Diagnostic Accuracy of Periprosthetic Breast Infection: Novel Application of the Alpha Defensin-1 Biomarker

Prompt, accurate diagnosis of breast implant infection is critical to minimizing patient morbidity. Bacterial culture false negative rate approaches 25%-30%, and better costeffective testing modalities are needed. Alpha defensin-1 (AD-1) is a neutrophil-mediated biomarker for microbial infection. With sensitivity/specificity of 97% and 96%, it has replaced culture as the preferred diagnostic modality for orthopedic periprosthetic infection, but has yet to be investigated in breast reconstruction. This pilot study compares the diagnostic performance of AD-1 to bacterial culture in suspected periprosthetic breast infection.

Patients with prosthetic breast reconstruction and suspected periprosthetic infection were prospectively studied. Implant pocket fluid was analyzed with gram stain and culture, AD-1 assay, and adjunctive markers. Demographics, operative history, prosthetic characteristics, and antibiotic exposure were collected, and diagnostic performance of each test was compared.

Fifteen breasts with suspected periprosthetic breast infection were included, 10 (66.7%) of which were acutely infected. Gram stain correctly identified only 1 of 10 infections, whereas culture failed to identify 1 infection and reported equivocal/false-positives in 2 noninfected samples. AD-1, however, correctly classified all 15 samples. AD-1 exhibited 100% sensitivity and specificity, comparing favorably to culture (sensitivity: 90%, specificity: 60%), although this did not reach significance (P=0.22). Infected breasts also demonstrated significantly higher adjunctive marker levels compared to noninfected breasts.

This study demonstrates the utility of AD-1 in diagnosing periprosthetic breast infection. Combining AD-1 with adjunctive inflammatory markers may allow more accurate, prompt detection of implant infection which may reduce morbidity and reconstructive failures.