Rapid antimicrobial susceptibility test, based on an analysis of changes in morphology and growth pattern of a microbial cell under different concentrations of various antimicrobial agents, and automated cell image analysis system therefor
Inventors
JUNG, Yong-Gyun • Kim, Eun-Geun • Yoo, Jung Heon • Kwon, Sunghoon • Choi, Jungil • Kim, Hee Chan • LEE, Jung Chan • Kim, Eui Jong • Song, Sang Hoon • Joo, Sei Ick • Lee, Ji Soo
Assignees
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Publication Number
US-10947575-B2
Publication Date
2021-03-16
Expiration Date
Abstract
Provided are a rapid antimicrobial susceptibility test, based on an analysis of changes in morphology and growth pattern of a microbial cell under different concentrations of various antimicrobial agents, and an automated cell image analysis system therefor. The antimicrobial susceptibility test is rapidly performed based on an analysis of changes in morphology and growth pattern of a microbial cell under different concentrations of various antimicrobial agents, and this makes it possible to obtain highly reliable test results faster by six to seven times than the standard method recommended by Clinical and Laboratory Standards Institute (CLSI).
Core Innovation
The invention provides an automated cell image analysis system configured to perform an antimicrobial susceptibility (AST) method by analyzing changes in morphology and growth pattern of a microbial cell under antimicrobial agents. The system determines antimicrobial susceptibility based on observed, time-dependent morphology and growth pattern changes measured in cultured microbial cells exposed to antimicrobial agents.
The system includes a culture chip for culture of a microbe, antimicrobial cells, and an antimicrobial agent, and for imaging a change in morphology and growth pattern of a microbial cell. An optical image detector films a culturing region of the microbial cell and detects an image of the microbial cell, and a detected image analyzer analyzes the detected image to obtain information on a total area occupied by microbial cells, the number of microbial cells, and a total length of microbial cells.
The change in morphology and growth pattern is classified into dividing, no-change, filament formation, and swelling formation according to the total area occupied by microbial cells, the number of microbial cells, and the total length of microbial cells. Antimicrobial susceptibility is then determined based on the classification of the change in morphology and growth pattern of the microbial cells.
Claims Coverage
The independent claim is directed to an automated cell image analysis system for an AST method that cultures, images, quantifies morphology/growth metrics, classifies morphology into four categories, and determines susceptibility from that classification. Dependent claims further specify optical illumination and camera types and add threshold-based analysis rules using area and length-to-cell ratios at multiple time points.
Automated cell image analysis system for antimicrobial susceptibility
An automated cell image analysis system configured to perform an antimicrobial susceptibility (AST) method based on analysis of changes in morphology and growth pattern of a microbial cell under antimicrobial agents, including a culture chip, an optical image detector filming a culturing region, and a detected image analyzer that obtains total area occupied by microbial cells, the number of microbial cells, and a total length of microbial cells and determines antimicrobial susceptibility.
Morphology and growth classification for susceptibility determination
Classifying the change in morphology and growth pattern of microbial cells into dividing, no-change, filament formation, and swelling formation according to the total area occupied by microbial cells, the number of microbial cells, and the total length of microbial cells, and determining antimicrobial susceptibility based on the classification.
Illumination selection for the optical image detector
Configuring the optical image detector to include a tungsten lamp, an LED device, or a laser light source.
CCD or CMOS optical camera implementation
Characterizing the optical image detector by using a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) camera.
Threshold-based decision rule using time-point area ratios
Analyzing microbial cell images by calculating an area ratio of total microbial cell area at 4 hours versus 0 hours, comparing it to thresholds T1, T2, and T3, and classifying the microbial cell as resistant or susceptible based on the ratio A3/A1 and conditions involving A3/A2.
Multi-metric, multi-threshold morphology and susceptibility classification
Analyzing microbial cell images by computing area and length-to-cell ratios at different time points, comparing these ratios to threshold values, classifying morphology and growth patterns as filament or swelling, and determining whether the microbial cells are susceptible or resistant to an antimicrobial agent based on the comparison results.
Overall, the claim set covers an automated AST system that uses culture chip imaging and image analysis to extract total occupied area, cell number, and total cell length, classifies morphology/growth changes into dividing/no-change/filament/swelling, and determines susceptibility from that classification; additional dependent claims define detector illumination and camera type and provide threshold-based classification rules using time-point area ratios and combined area/length-to-cell ratios.
Stated Advantages
Faster AST results compared with conventional methods, reported as approximately 6–7x faster in the provided summary.
Improved reliability of antimicrobial susceptibility determination compared with conventional CLSI-based AST/BMD that infers susceptibility mainly from turbidity/OD.
Higher categorical agreement and lower error rates in comparison results, with particular improvements for filament/swelling cases and β-lactam interactions in gram-negative bacteria.
Documented Applications
Rapid antimicrobial susceptibility testing (AST) by determining susceptibility from time-dependent microbial morphology/growth changes under antimicrobial agents using automated cell image analysis and classification into dividing, no-change, filament formation, and swelling formation.
Assessment of antimicrobial susceptibility for antimicrobial agent panels referenced in the summary, including β-lactam antimicrobial agents (e.g., piperacillin and piperacillin/tazobactam) and other agents (e.g., imipenem, meropenem, amikacin, ciprofloxacin, gentamicin, clindamycin, levofloxacin, linezolid, vancomycin), with reported comparisons to MIC QC agreement and performance criteria.
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