Broth Dilution Method
Broth Dilution Method - Related Videos
12:39
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.
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.
10:53
Serial Dilutions and Plating: Microbial Enumeration
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2023
Source: Jonathan F. Blaize1, Elizabeth Suter1, and Christopher P. Corbo1 1 Department of Biological Sciences, Wagner College, 1 Campus Road, Staten Island NY, 10301 Quantitative assessment of prokaryotes can be onerous given their abundance, propensity for exponential proliferation, species diversity within a population, and specific physiological needs. Compounding this challenge, is the four-phase nature in which bacteria replicate (lag, log, stationary and death). The ability to accurately...
05:35
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...
02:59
Solution Concentration and Dilution
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2020
The relative amount of a given solution component is known as its concentration. Often, though not always, a solution contains one component with a concentration that is significantly greater than that of all other components. This component is called the solvent and may be viewed as the medium in which the other components are dispersed or dissolved. Solutions in which water is the solvent are, of course, very common on our planet. A solution in which water is the solvent is called an aqueous...
FAQs
The serial dilution creates a range of antimicrobial concentrations that can be evaluated under the same growth conditions. After incubation, researchers examine each tube or well for visible microbial growth and locate the lowest concentration at which growth is not observed. This concentration provides a standardized point for comparing antimicrobial activity.
A standardized microbial suspension helps ensure that the different antimicrobial concentrations are challenged with comparable amounts of microorganism. Without that consistency, differences in visible growth could reflect variation in the inoculum rather than antimicrobial activity. Defined incubation conditions further support meaningful comparisons among concentrations and between experiments.
The MIC identifies the lowest concentration associated with no visible growth, but that result alone does not establish that the microorganisms were killed. Researchers can subculture material from clear wells or tubes into suitable growth conditions. If growth returns, the antimicrobial inhibited growth; if it does not, the result supports determination of the minimum bactericidal concentration, or MBC.
Comparing MIC values across antimicrobial agents or microbial isolates provides evidence about relative antimicrobial potency and susceptibility. Markedly different results can also help identify reduced responsiveness consistent with resistance. In infection research, these comparisons support systematic susceptibility testing rather than relying only on whether growth occurs at a single concentration.
The workflow begins by preparing serial antimicrobial dilutions in liquid growth medium. Each dilution is inoculated with a standardized microbial suspension, then incubated under defined conditions. Researchers inspect the resulting tubes or wells for visible growth and record the lowest concentration without growth as the MIC. Selected clear samples may then be subcultured for MBC assessment.
The method is useful when researchers need quantitative information about how an antimicrobial affects a microorganism. It supports comparisons among agents, evaluation of resistance, and susceptibility testing relevant to treatment selection. Within immunology and infection research, the resulting MIC and, when assessed, MBC values help distinguish inhibited growth from evidence of microbial killing.