Rapid Antimicrobial Susceptibility Testing on Clinical Urine Samples by Video-Based Object Scattering Intensity Detection

Abstract

To combat the ongoing public health threat of antibiotic-resistant infections, a technology that can quickly identify infecting bacterial pathogens and concurrently perform antimicrobial susceptibility testing (AST) in point-of-care settings is needed. Here, we develop a technology for point-of-care AST with a lowmagnification solution scattering imaging system and a real-time video-based object scattering intensity detection method. The low magnification (1−2×) optics provides sufficient volume for direct imaging of bacteria in urine samples, avoiding the time-consuming process of culture-based bacterial isolation and enrichment. Scattering intensity from moving bacteria and particles in the sample is obtained by subtracting both spatial and temporal background from a short video. The time profile of scattering intensity is correlated with the bacterial growth rate and bacterial response to antibiotic exposure. Compared to the image-based bacterial tracking and counting method we previously developed, this simple image processing algorithm accommodates a wider range of bacterial concentrations, simplifies sample preparation, and greatly reduces the computational cost of signal processing. Furthermore, development of this simplified processing algorithm eases implementation of multiplexed detection and allows real-time signal readout, which are essential for point-of-care AST applications. To establish the method, 130 clinical urine samples were tested, and the results demonstrated an accuracy of ∼92% within 60−90 min for UTI diagnosis. Rapid AST of 55 positive clinical samples revealed 98% categorical agreement with both the clinical culture results and the on-site parallel AST validation results. This technology provides opportunities for prompt infection diagnosis and accurate antibiotic prescriptions in point-of-care settings.

High-Throughput Screening Identifies Synthetic Peptides with Antibacterial Activity against Mycobacterium abscessus and Serum Stability

“…Deidentified excess and residual clinical urine samples were obtained from the clinical microbiology laboratory at Mayo Clinic Hospital, Phoenix, Arizona (approved by Mayo Clinic Biospecimen Subcommittee BIO00015462). − E. coli urinary tract infection clinical isolates were cultured as described above and stored in 15-20% glycerol at −70 °C.…”

Label-free 1D microfluidic dipstick counting of microbial colonies and bacteriophage plaques

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Rapid Detection of Urinary Tract Infection in 10 min by Tracking Multiple Phenotypic Features in a 30 s Large-Volume Scattering Video of Urine Microscopy

“…In our previous work, we achieved direct AST results on clinical urine samples in 60−90 min with largevolume solution scattering imaging (LVSi) by tracking singlecell division 42 and by object scattering intensity detection. 43 Here, we present a POC compatible UTI screening approach that directly analyzes urine samples via LVSi tracking of multiple intrinsic bacterial phenotypic features. This rapid detection (RD) screening method detects bacteria in less than 10 min, reducing unnecessary antibiotic use and clinical laboratory resources.…”

“…This method also cannot differentiate normal bacterial growth from those antibiotics that promote cell elongation. In our previous work, we achieved direct AST results on clinical urine samples in 60–90 min with large-volume solution scattering imaging (LVSi) by tracking single-cell division and by object scattering intensity detection . Here, we present a POC compatible UTI screening approach that directly analyzes urine samples via LVSi tracking of multiple intrinsic bacterial phenotypic features.…”