Checkerboard Assay
Checkerboard Assay - Related Videos
11:15
Quadruple-Checkerboard: A Modification of the Three-Dimensional Checkerboard for Studying Drug Combinations
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Cited by 3 •
2021
This protocol describes how to study all possible combinations that can be obtained between four drugs in one single experiment. This method is based on the standard 96-well plate micro dilution assay and the calculation of fractional inhibitory concentrations (FICs) to evaluate the results.
10:39
Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating
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Cited by 10 •
2016
The measurement protocol and data analysis procedure are given for obtaining transverse coherence of a synchrotron radiation X-ray source along four directions simultaneously using a single 2-D checkerboard phase grating. This simple technique can be applied for complete transverse coherence characterization of X-ray sources and X-ray optics.
06:09
Detection of Human Islet Autoantibodies Using an Electrochemiluminescence Assay
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2025
This video showcases the electrochemiluminescence detection of islet autoantibodies in human serum. The antibodies in the serum bridge the ruthenium-conjugated antigen to the biotinylated capture antigen, forming complexes that are detected by electrochemiluminescence measurements.
09:39
A Behavioral Assay to Measure Responsiveness of Zebrafish to Changes in Light Intensities
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Cited by 222 •
2008
We developed the Visual-Motor Response to quantitate the motor output of larval zebrafish in response to light increments and decrements. We also examined zebrafish vision mutants, including the no optokinetic response (nrc) mutants, which were thought to be completely blind when tested by another vision assay, the optokinetic reflex.
12:03
Antimicrobial Synergy Testing by the Inkjet Printer-assisted Automated Checkerboard Array and the Manual Time-kill Method
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Cited by 42 •
2019
Antimicrobial synergy testing is used to evaluate the effect of two or more antibiotics used in combination and is typically performed by one of two methods: the checkerboard array or the time-kill assay. Here, we present an automated, inkjet printer-assisted checkerboard array synergy technique and a classic time-kill synergy study.
FAQs
A two-dimensional matrix reveals how the activity of one antimicrobial changes across multiple concentrations of a second agent. Testing paired concentrations makes it possible to compare the combined inhibitory effect with the agents’ individual effects. This design helps identify interactions that would remain hidden if the agents were evaluated only in separate, single-agent experiments.
The fractional inhibitory concentration index summarizes the inhibitory contribution of each antimicrobial within a tested combination. By relating combination activity to the minimum inhibitory concentrations of the individual agents, it provides a quantitative basis for classifying the interaction as synergistic, additive, or antagonistic. The index therefore complements direct observations of microbial growth inhibition.
Growth inhibition at each matrix position shows whether a particular concentration pair suppresses the infectious organism under investigation. Comparing these positions across the concentration range identifies combinations that achieve inhibition at lower levels of one or both agents. The resulting pattern supplies the experimental evidence used for minimum inhibitory concentration and interaction analysis.
A synergistic interaction may allow effective inhibition with reduced concentrations of one or both antimicrobials, creating a dose-sparing strategy for experimental treatment design. Combination testing can also reveal potentially useful activity against organisms that are difficult to control with a single agent. These findings are especially relevant when researchers are investigating approaches to antimicrobial resistance.
The assay begins by preparing serial concentrations of two antimicrobial agents and arranging their combinations in a two-dimensional matrix. The infectious organism is then evaluated for growth inhibition across the matrix. Researchers determine the minimum inhibitory concentration for relevant combinations and use those measurements to calculate the fractional inhibitory concentration index and classify the interaction.
The assay provides a concentration-by-concentration profile of combined antimicrobial activity rather than a single yes-or-no outcome. Researchers can identify which pairs inhibit growth, determine the minimum inhibitory concentration associated with those pairs, and quantify the interaction through the fractional inhibitory concentration index. This supports comparisons among candidate combinations and informs subsequent experimental treatment design.
Researchers use the method when they need to evaluate whether two antimicrobial agents perform better together than expected from their separate activity. It can support screening of combination therapies, investigation of dose-sparing strategies, and study of approaches intended to overcome antimicrobial resistance. The results help prioritize combinations for further experimental evaluation against infectious organisms.
Within immunology and infection research, the assay supplies a controlled way to characterize antimicrobial combinations against infectious organisms. Its measurements can connect concentration choices with inhibition outcomes, helping researchers design experiments that test more effective combination treatments. The approach is particularly useful for examining therapeutic strategies intended to improve control of infection or address resistance-related challenges.