USE OF A SCATTERED LIGHT INTEGRATING COLLECTOR FOR POINT-OF-CARE TESTING TO DETECT BACTERIA IN FLUID SAMPLES FROM PROSTHETIC JOINT INFECTIONS OF THE HIP

Infection complicates 0.5–1% of the 72,000 total hip replacements (THRs) undertaken annually in the UK. Early targeted antibiotic therapy has an impact on patient outcomes, however rapid treatment with narrow spectrum antibiotics is currently limited by the available methods of confirming infection and antimicrobial sensitivities. We propose a novel diagnostic technology, the Scattered Light Integrating Collector (SLIC), which allows the study of bacterial colony dynamics in real time, with a sensitivity 1000 times greater than conventional methods. Serial dilutions of overnight bacterial culture were examined by SLIC. A positive result for infection was defined as a stable/rising signal which was significantly above baseline (control) signal. Susceptibility to a panel of antibiotics was examined. Time to obtaining a result on sensitivity was defined as the time at which the SLIC signal was static/declining, and significantly different to the positive control. Concordance against current standards of care was established. In the case study of a patient with a known infected THR, intraoperative samples were obtained at the time of revision surgery and were run through SLIC. SLIC detected the presence of bacteria at a sensitivity of 100 colony forming units (CFU)/ml, in under 15 minutes, with a linear response across its entire range of detection. A dose dependent effect on the time to detection of antimicrobial sensitivity was apparent, with almost immediate detection of growth suppression at the highest antibiotic concentrations. In the patient case study, SLIC was able to detect the presence of bacterial infection in under 30 minutes, with sensitivity to a number of antibiotics also detected in under 30 minutes. We have shown that SLIC is both faster and more sensitive than conventional culture and spectrometry methods. On the basis of these results, we infer that a patient could be started on an antibiotic sensitive for their specific prosthetic joint infection within the time taken to complete their revision surgery.