Acute peri-prosthetic joint infection: improving diagnosis through the novel alpha-defensins test

Abstract

Background. The matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has recently been proposed as novel alpha-defensins test for diagnosis of peri-prosthetic joint infections (PJIs). The aim of the current study is to assess the diagnostic accuracy of alpha-defensins MALDI-TOF MS in case of acute PJIs. Methods. This prospective study included a series of 10 consecutive patients affected by PJIs according to the 2018 MSIS criteria. Synovial fluids were assessed for routine synovial fluid tests and alpha-defensins measurement with MALDI-TOF MS. Sensitivity, specificity, positive, and negative predictive values (PPV and NPV) were assessed. Results. Six females and 4 males with acute PJIs were included. The mean age was 72.5 (range 67-79), and the mean time elapsed from primary arthroplasty to PJIs was 52 days (range 13-90). Eight TKA and 2 THA were evaluated. The involved bacteria were Staphylococcus aureus in 4 patients, coagulase-negative Staphylococcus species in 3 patients, Enterococcus species in 3 patients, and Pseudomonas aeruginosa in 1 patient. Three cases were characterized by polymicrobial infection. The MALDI-TOF alpha-defensin test correctly identified all 10 patients with acute PJIs. According to the current preliminary results the MALDI-TOF assay showed a 100% sensitivity, specificity, PPV, and NPV. Conclusions. The novel alpha-defensins MALDI-TOF MS test showed promising results with high sensitivity and specificity in the diagnosis of acute PJIs. The reliability of the test in case of acute PJI could allow surgeons to manage the infection with a less invasive procedure with several advantages for patients. The findings of the present study seemed to confirm that the novel assay, which needs only few milliliters of sample, provides rapid results, and has substantial cost-effectiveness, and thus may be a useful diagnostic tool in clinical practice, even in case of acute PJIs. Further studies are needed to confirm these results on a larger series of patients.

Dithiotreitol pre-treatment of synovial fluid samples improves microbiological counts in peri-prosthetic joint infection

“…Analysis of synovial fluids represents an important tool for diagnosis of bone and joint infections, including prosthetic ones, since it can contribute to optimize patient management before surgery. In the recent past, it has been widely demonstrated that measurement of inflammatory markers in synovial fluids is a more specific approach than their evaluation in blood [22][23][24]. Nonetheless, culture remains crucial for the diagnosis of osteo-articular infections and particularly of PJI [25].…”