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Once a bacterium has been identified following microbiological culture, antibiotics are selected for susceptibility testing. [5] Susceptibility testing methods are based on exposing bacteria to antibiotics and observing the effect on the growth of the bacteria (phenotypic testing), or identifying specific genetic markers (genetic testing). [6]
Voges–Proskauer / ˈ f oʊ ɡ ə s ˈ p r ɒ s k aʊ. ər / or VP is a test used to detect acetoin in a bacterial broth culture. The test is performed by adding alpha-naphthol and potassium hydroxide to the Voges-Proskauer broth, which is a glucose-phosphate broth that has been inoculated with bacteria. A cherry red color indicates a positive ...
An example of such testing is antibiotic susceptibility testing by measurement of minimum inhibitory concentration which is routinely used in medical microbiology and research. If a suspension used is too heavy or too dilute, an erroneous result (either falsely resistant or falsely susceptible) for any given antimicrobial agent could occur.
Etest (previously known as the Epsilometer test) is a way of determining antimicrobial sensitivity by placing a strip impregnated with antimicrobials onto an agar plate. A strain of bacterium or fungus will not grow near a concentration of antibiotic or antifungal if it is sensitive.
The catalase test tests whether a microbe produces the enzyme catalase, which catalyzes the breakdown of hydrogen peroxide. Smearing a colony sample onto a glass slide and adding a solution of hydrogen peroxide (3% H 2 O 2) will indicate whether the enzyme is present or not. Bubbling is a positive test while nothing happening is a negative result.
A laboratory specimen is sometimes a biological specimen of a medical patient's tissue, fluids, or other samples used for laboratory analysis to assist in differential diagnosis or staging of a disease process. These specimens are often the most reliable method of diagnosis, depending on the ailment.
The first test is read 48–72 hours after injection. If the first test is positive, consider the person infected. If the first test is negative, give a second test one to three weeks after the first injection. The second test is read 48–72 hours after injection. If the second test is positive, consider the person infected in the distant past ...
For example, if a microbiologist observes colonies that resemble a Staphylococcus species, they may perform a catalase test to confirm that it belongs to the genus Staphylococcus, and a coagulase test to determine whether it is a coagulase-negative staphylococcus or a more pathogenic species, such as S. aureus. [3]: 101 [8]: 203