Prosthetic Joint Infections Test Receives CE Marking

By LabMedica International staff writers
Posted on 05 Feb 2015

Image: On the left are the typical radiographic findings of infection with irregular bone destruction and periosteal reaction. In many cases however the infection is really low grade and difficult to establish (Photo courtesy of Radiological Society of the Netherlands).

The first diagnostic test that can detect in patients' blood antibodies against several bacteria types frequently responsible for prosthetic infections, in particular Staphylococcus, the most often encountered type in such infections.

The new test has received Conformité Européenne (CE) marking, and provides qualitative information in a couple of hours for each targeted bacteria types, which enables caregivers, in association with the usual assessments, to accelerate and improve the care of patients who have prosthetic joint infections.

This BJI InoPlex test (Diaxonit; Paris France) requires 10 µl of serum taken by a simple blood draw and can be easily repeated. After adequate preparation, the test is carried out directly in the biology laboratory of the hospital with a standard Luminex instrument (Luminex; Austin, TX, USA). The test uses a combination of several recombinant protein antigens to test for anti-Staphylococcus immunoglobulin G (IgG for S. aureus and S. epidermidis). The BJI InoPlex kit contains various reagents necessary to perform the test, a 96-well filter plate, calibration CD-ROM containing specific calibration information for each batch and a user manual. The BJI InoPlex software is used to interpret the data and report a result per family of bacteria.

The performance of BJI InoPlex compared with microbiological results on intraoperative samples are respectively 82.2% for specificity and 75.9% for sensitivity, all types of targeted staphylococci included. Other bacteria targeted by BJI InoPlex are less frequent in the prevalence of prosthetic infections, and the incidence of proven intraoperative infections with these bacteria also ended up being limited in the study cohort. The high specificity of the test for two families of bacteria, Group B-Streptococcus and Propionibacterium acnes, preferentially orients towards the absence of an immune response against these types of bacteria, BJI InoPlex is being used in addition to other tests performed.

Related Links:
Diaxonit
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