Minimum inhibitory concentration
Encyclopedia
In microbiology
, minimum inhibitory concentration (MIC) is the lowest concentration
of an antimicrobial
that will inhibit the visible growth
of a microorganism
after overnight incubation. Minimum inhibitory concentrations are important in diagnostic laboratories to confirm resistance of microorganisms to an antimicrobial agent and also to monitor the activity of new antimicrobial agents. A lower MIC is an indication of a better antimicrobial agent. An MIC is generally regarded as the most basic laboratory measurement of the activity of an antimicrobial agent against an organism.
, BSAC or EUCAST. There are several commercial methods available, including the well established Etest strips and the recently launched Oxoid MICEvaluator method.
The Etest system comprises a predefined and continuous concentration gradient of different antimicrobial agents, which when applied to inoculated agar plates and incubated, create ellipses of microbial inhibition.http://gold.aecom.yu.edu/id/micro/mic_etest-72.jpg The MIC is determined where the ellipse of inhibition intersects the strip, and is easily read off the MIC reading scale on the strip.http://gold.aecom.yu.edu/id/micro/mic_etest_menisc-400.jpg
to specific antimicrobial agents. Currently, there are a few web-based, freely accessible MIC databases.
Microbiology
Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell , cell clusters or no cell at all . This includes eukaryotes, such as fungi and protists, and prokaryotes...
, minimum inhibitory concentration (MIC) is the lowest concentration
Concentration
In chemistry, concentration is defined as the abundance of a constituent divided by the total volume of a mixture. Four types can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration...
of an antimicrobial
Antimicrobial
An anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...
that will inhibit the visible growth
Cell growth
The term cell growth is used in the contexts of cell development and cell division . When used in the context of cell division, it refers to growth of cell populations, where one cell grows and divides to produce two "daughter cells"...
of a microorganism
Microorganism
A microorganism or microbe is a microscopic organism that comprises either a single cell , cell clusters, or no cell at all...
after overnight incubation. Minimum inhibitory concentrations are important in diagnostic laboratories to confirm resistance of microorganisms to an antimicrobial agent and also to monitor the activity of new antimicrobial agents. A lower MIC is an indication of a better antimicrobial agent. An MIC is generally regarded as the most basic laboratory measurement of the activity of an antimicrobial agent against an organism.
Determination
MICs can be determined by agar or broth dilution methods usually following the guidelines of a reference body such as the CLSIClinical and Laboratory Standards Institute
Clinical and Laboratory Standards Institute is a volunteer driven, membership supported, nonprofit, standards organization. CLSI promotes the development and use of voluntary laboratory consensus standards and guidelines within the health care community....
, BSAC or EUCAST. There are several commercial methods available, including the well established Etest strips and the recently launched Oxoid MICEvaluator method.
The Etest system comprises a predefined and continuous concentration gradient of different antimicrobial agents, which when applied to inoculated agar plates and incubated, create ellipses of microbial inhibition.http://gold.aecom.yu.edu/id/micro/mic_etest-72.jpg The MIC is determined where the ellipse of inhibition intersects the strip, and is easily read off the MIC reading scale on the strip.http://gold.aecom.yu.edu/id/micro/mic_etest_menisc-400.jpg
Clinical significance
Clinically, the minimum inhibitory concentrations are used not only to determine the amount of antibiotic that the patient will receive but also the type of antibiotic used, which in turn lowers the opportunity for microbial resistanceAntibiotic resistance
Antibiotic resistance is a type of drug resistance where a microorganism is able to survive exposure to an antibiotic. While a spontaneous or induced genetic mutation in bacteria may confer resistance to antimicrobial drugs, genes that confer resistance can be transferred between bacteria in a...
to specific antimicrobial agents. Currently, there are a few web-based, freely accessible MIC databases.
See also
- Bacteriostatic agentBacteriostatic agentA bacteriostatic agent or bacteriostat, abbreviated Bstatic, is a biological or chemical agent that stops bacteria from reproducing, while not necessarily harming them otherwise. Depending on their application, bacteriostatic antibiotics, disinfectants, antiseptics and preservatives can be...
Role of thumb the less the number(concentration) it gives better coverage. - MBCMinimum Bactericidal ConcentrationThe Minimum Bactericidal Concentration is the lowest concentration of antibiotic required to kill the germ. Not as commonly seen as the Minimum inhibitory concentration . It can be determined from broth dilution MIC tests by subculturing to agar media without antibiotics...
(Minimum Bactericidal Concentration)