Drug Susceptibility Testing
Drug Susceptibility Testing - Related Videos
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Antimicrobial Susceptibility Testing of Mycobacterium Tuberculosis Complex for First and Second Line Drugs by Broth Dilution in a Microtiter Plate Format
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Cited by 29 •
2011
Antimicrobial susceptibility testing of Mycobacterium tuberculosis is challenging but critical for patient care. This microtiter plate format offers testing of 12 antimycobacterial drugs and provides minimum inhibitory concentration (MIC) values, which will aid in appropriate treatment.
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Antibiotic Susceptibility Testing: Epsilometer Tests to Determine MIC Values of Two Antibiotics and Evaluate Antibiotic Synergy
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2023
Source: Anna Bläckberg1, Rolf Lood1 1 Department of Clinical Sciences Lund, Division of Infection Medicine, Biomedical Center, Lund University, 221 00 Lund Sweden Knowledge of the interactions between antibiotics and bacteria is important in understanding how microbes evolve antibiotic resistance. In 1928, Alexander Fleming discovered penicillin, an antibiotic that exerts its antibacterial function by interfering with cell wall regeneration (1). Other antibiotics with diverse mechanisms of...
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A Broth Microdilution Method for Antibiotic Susceptibility Testing of Gram-Positive Bacteria
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2025
Source: Koeth, L. M., et. al., A Reference Broth Microdilution Method for Dalbavancin In Vitro Susceptibility Testing of Bacteria that Grow Aerobically. J. Vis. Exp. (2015).This video demonstrates the broth microdilution method for determining the minimum inhibitory concentration (MIC) of a lipoglycopeptide antibiotic against Gram-positive bacteria. It covers bacterial colony isolation, dilution, inoculation of microplate wells with varying antibiotic concentrations, and verification of culture...
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Stress-induced Antibiotic Susceptibility Testing on a Chip
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Cited by 5 •
2014
We have developed a microfluidic platform for rapid antibiotic susceptibility testing. Fluid is passed at high speeds over bacteria immobilized on the bottom of a microfluidic channel. In the presence of stress and antibiotic, susceptible strains of bacteria die rapidly. However, resistant bacteria can survive these stressful conditions.
11:28
A Reference Broth Microdilution Method for Dalbavancin In Vitro Susceptibility Testing of Bacteria that Grow Aerobically
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Cited by 33 •
2015
Here, we present a protocol for determination of dalbavancin susceptibility of clinically relevant Gram-positive bacteria using a broth microdilution reference methodology.
FAQs
Interpretation depends on how microbial growth changes across defined drug concentrations. A progressive reduction in growth indicates increasing inhibition, while the minimum inhibitory concentration identifies the lowest concentration associated with no visible growth. This concentration-response relationship allows researchers to compare the same microorganism with different drugs and to distinguish stronger or weaker inhibitory effects under the tested conditions.
Inhibition zones provide a visible measurement of how far growth is prevented around a drug source, whereas the minimum inhibitory concentration gives a concentration-based endpoint. Both describe antimicrobial activity, but they express results differently. Using either measure helps characterize microbial phenotypes, while comparing the two can support a more detailed assessment of responses to selected drugs.
Resistance becomes evident when a microorganism continues growing despite drug exposure or requires a higher concentration for visible inhibition. Comparing these responses among microbial isolates, drugs, or time points can reveal differences in susceptibility and emerging resistance patterns. The resulting data connect a biological growth phenotype with antimicrobial pressure, supporting investigations of how treatment responses vary.
A typical assay begins by exposing a microorganism to one or more antimicrobial drugs at defined concentrations. Growth is then assessed by observing inhibited zones or identifying the lowest concentration that prevents visible growth. The measured endpoint is recorded for comparison across drugs or microbial phenotypes. This workflow converts growth behavior under exposure into interpretable susceptibility data.
Researchers apply the method when they need to compare how microorganisms respond to specific antimicrobial drugs. In clinical microbiology, results can contribute to selecting effective therapies. In epidemiology, comparisons can help track susceptibility patterns, while laboratory research uses the measurements to study microbial phenotypes and investigate emerging antimicrobial resistance.
Results can show that different microorganisms, or different isolates of the same organism, respond differently to the same drug. Such variation provides evidence of phenotypic diversity and can be compared across samples or investigations. In epidemiology, these patterns help characterize resistance trends; in research, they support comparisons between biological responses and drug exposure.