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Microscopy for infectious agents

Microscopy for infectious agents is a microscopic examination to detect or identify harmful microorganisms.

Microscopy for infectious agents
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Individual microorganisms, such as viruses, bacteria, and fungi, are too small to see without using a microscope. In microscopy, highly magnified images of microorganisms are produced so that they can be seen and identified. Microscopy can be performed on any type of sample from the body, such as blood, urine, or other body fluids.

Sometimes, a test sample is examined immediately in the doctor's surgery or in a laboratory. For example, a sample of urine may be examined under a microscope to identify bacteria. However, a sample often contains so few organisms that they cannot be detected easily. In these cases, the microorganisms may be grown (cultured) to increase their numbers before microscopy or other tests are performed (see Culture and tests for drug sensitivity).

How is microscopy for infectious agents done?

Different microscopes are used to identify different organisms. Bacteria are usually identified with a light microscope. Viruses, which are much smaller than bacteria, are examined with a more powerful electron microscope.

Most samples are treated with stains before viewing to aid the detection and identification of any microorganisms they contain. The Gram stain is one of the most commonly used stains for differentiating between the different types of bacterium. Samples to be examined using an electron microscope have to be set in resin, thinly sliced, and coated with metals beforehand.

When the samples have been prepared, any microorganisms present are studied under a microscope. Different types of microorganism can be recognized by their size, their shape, and how they react with the stains.

Posted 09.09.2010


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