Rapid antimicrobial susceptibility test based on in-situ time-lapsed imaging of microcolonies

Abstract:

[Objective] Over 7 million people die from bacterial infections every year due to the inappropriate or untimely use of antibiotics. Antimicrobial susceptibility test (AST) is a routine method guiding antibiotic therapy in clinical practice, while the existing methods have limitations as they require at least 16–20 h to get the results. We aimed to develop a novel rapid AST method based on bacterial morphology analysis, which can improve the diagnosis efficiency and provide timely treatment for the patients with bacterial infections, especially for urgent cases. [Methods] We developed an in-situ time-lapsed imaging (ISM-TLI) technique for microcolonies by combining bacterial incubation, in vitro antibiotic treatment, microscopic imaging, and image processing algorithm. The combination of the imaging device with the algorithm enabled the tracing of the morphological changes of colonies treated with different concentrations of antibiotics in-situ and the rapid obtainment of AST results. [Results] This technique worked effectively for both Gram-positive and Gram-negative bacteria and could determine the minimum inhibitory concentration (MIC) within 2 h, with the results in agreement with those obtained with the clinical gold standard method. [Conclusion] Our rapid AST technique significantly reduced the turn-around-time for obtaining the AST profile and had great potential for AST of a wide range of other strains.

Key words:Hough transform;bacterial morphology;image recognition;rapid antimicrobial susceptibility test;in-situ incubation