Broth microdilution is a method used to test the susceptibility of

microorganisms A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...

. It is the most commonly used method to perform this test in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...

. __TOC__

Process

During testing, multiple

microtiter plate A microplate, also known as a microtiter plate (''Microtiter'' is a registered trademark in the United States, therefore it should not be used generically without attribution), microwell plate or multiwell, is a flat plate with multiple "wells" ...

s are filled with a certain broth, according to the needs of target bacteria. Varying concentrations of the antibiotics and the bacteria to be tested are then added to the plate. The plate is then placed into a non-

incubator An incubator is anything that performs or facilitates various forms of incubation, and may refer to: Biology and medicine * Incubator (culture), a device used to grow and maintain microbiological cultures or cell cultures * Incubator (egg), a de ...

and incubated at thirty-seven degrees Celsius for sixteen to twenty hours. Following the allotted time, the plate is removed and checked for bacterial growth. If the broth became cloudy or a layer of cells formed at the bottom, then bacterial growth has occurred. The results of the broth microdilution method are reported in Minimum Inhibitory Concentration (MIC), or the lowest concentration of antibiotics that stopped bacterial expansion.

Advantages

The broth microdilution method can be used to test the susceptibility of microorganisms to multiple antibiotics at once. Broth microdilution is also highly accurate. The accuracy of its results are comparable to agar dilution, the

gold standard A gold standard is a Backed currency, monetary system in which the standard economics, economic unit of account is based on a fixed quantity of gold. The gold standard was the basis for the international monetary system from the 1870s to the ...

of susceptibility testing. Other advantages include the commercial availability of plates, the ease of testing and storing the plates, and the ability for the results of some tests to be read by machines.

References

{{Reflist Antimicrobial resistance