Chronic infections associated with implanted medical devices such as prosthetic joints are difficult to diagnose and treat due to biofilm formation by the causative pathogens. Bacterial infections often persist in the form of protective biofilms (65 – 80% of all infections), a mode of growth which reduces the effectiveness of the host immune system as well as antimicrobial drugs. Pathogen identification often relies on microbial culture that requires days to weeks, and in the case of chronic biofilm infections, lacks sensitivity. Diagnosis of infection is often delayed past the point of effective treatment such that only the removal of the implant is curative.
UMB researchers developed a serological assay to detect antibodies to unique biofilm-associated antigens of Staphylococcus aureus. Specific antigens were selected based on their upregulated and sustained expression in a biofilm, both in vitro and in vivo. In tests with patient samples derived from orthopedic implant infection cases, UMB researchers demonstrated clinical diagnostic utility of the assay, with 100% specificity & 91% sensitivity. The Staph aureus biofilm assay promises a rapid, serology-based diagnosis of infection that can lead to earlier, life-saving interventions.
Implanted medical devices (~ 5 million/year in U.S.) such as pacemakers, artificial heart valves, catheters, replacement hip joints, bone cement and other surgical implants are all prone to biofilm development, as are the chronic wounds associated with surgical sites, trauma, and diabetic foot ulcers (~ 8 million chronic wound patients in the U.S. and EU, per 2016 data). The ability of current diagnostic tests to detect biofilms before clinical symptoms develop is inadequate. Molecular techniques such as PCR have increased sensitivity in the species-level identification of pathogens. However, PCR is prone to false positives, and given that 10 – 40% of the global population is colonized by S. aureus, there’s quite a potential for misdiagnosis.
- High specificity & sensitivity of UMB’s assay demonstrated in clinical samples and a rabbit infection model
- Enables earlier-stage detection of infection
- Reliance on unique antigens associated with S. aureus biofilm mode
Stage of Development
Clinical diagnostic utility has been demonstrated with patient samples derived from orthopedic implant infection cases (see Harro et al., 2020)
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