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A novel diagnostic technology rapidly detects the presence of infection and defines antimicrobial sensitivities in organisms typical for joint infection.

Bone & joint research

Authors: Isabelle L Cochrane, Roselline Gabriella Gunarto, Frank Alexander Schildberg, Dieter Christian Wirtz, Robert J H Hammond, Phillip J Walmsley

AIMS: Infective arthritis is rare, but serious. Timely treatment with appropriate antimicrobial therapy is potentially life- and limb-saving, but our ability to deliver this is limited by current laboratory practices, which confer a delay of several days before antimicrobial sensitivities are available. We propose a novel diagnostic modality, the Scattered Light Integrating Collector (SLIC), which monitors bacterial growth in real time, allowing a diagnosis of infection to be made in minutes, and antimicrobial sensitivities to be delivered in under an hour.

METHODS: We collated data previously collected on SLIC relating to laboratory strains of and (MRSA) . Liquid cultures of the two organisms, with varying dilutions of target antibiotics, were compared in SLIC against positive (no antibiotic) and negative (no bacteria) controls. Three key measurements were derived: time to positivity (TTP - the timepoint at which significant bacterial growth was confirmed), time to sensitivities (TTS - the timepoint of statistically significant growth inhibition conferred by antibiotics vs the positive control), and IC50 (50% growth suppression relative to control).

RESULTS: TTP for and MRSA was two minutes and 2.2 minutes, respectively. was sensitive to gentamicin, with a minimum TTS of one minute, and IC50 achieved in under 19 minutes for all doses. Similarly, susceptibility to vancomycin was established, with a minimum TTS of three minutes, and IC50 achieved in under 55 minutes for all but the lowest dose. MRSA was sensitive to rifampicin, with IC50 achieved in 16.5 minutes. Despite all tested antibiotics achieving TTS in under 30 minutes, only rifampicin achieved the criterion IC50 to declare susceptibility.

CONCLUSION: SLIC rapidly determines the presence of infection and characterizes antimicrobial susceptibilities in organisms typical for joint infection.

© 2026 Cochrane et al.

PMID: 42595340

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