When we speak of laboratory indicators, we are referring to the diagnostic approach used in the laboratory to diagnose infectious diseases. Although there are multiple indicators, all of them are really useful to characterise and learn about new species and, as just mentioned, to detect infectious agents such as parasites, bacteria or fungi.
As chemical suppliers, this article will talk about indicators and the different types that exist. You can find out much more useful information by visiting our blog and our extensive catalogue of chemical products – you can count on DC Fine Chemicals!
Laboratory indicators: types and techniques
Staining can also be referred to as colouring. Since microorganisms are too small to be seen with the naked eye, a study under a microscope is necessary in order to know their structure, size or composition. It is also much easier to examine micro-organisms with dyes or stains, which makes it easier to observe them.
Humans live in constant contact with micro-organisms. In many cases they are part of the normal flora of our environment without posing a health hazard. However, on other occasions they can cause pathologies, or in other words, they can cause skin or bone infections, etc. This is why it is important to identify and treat them.
Laboratory indicators thus describe the process by which various aspects of a bacterium, virus, protozoan, etc. can be identified with the help of dyes. They increase the distinctness of the sample and thus make the information obtained more reliable and accurate: they reveal its size and shape, trigger chemical reactions, and show the external and internal structures.
Indicators can be classified into two major groups. Simple staining is characterised by the use of a single dye. In this way, the entire sample is stained with a single colour and the cell morphology of the micro-organism in question is known. A differential staining uses more than one dye, revealing differences between cells or parts of cells. Differential indicators include others such as Gram differential staining, Ziehl-Neelsen differential staining and Wirtz differential staining.
The most commonly used dyes in this field are methylene blue, safranin and crystal violet. These, among others, are combined with cellular components such as nucleic acids or acidic polysaccharides.
Gram stain: among the most commonly used stains
Each of them follows established guidelines. To give an example, we will explain what one of the best known and most commonly used stains is: Gram staining. It has been used in the field of microbiology for more than a century, due to the beneficial developments that science has undergone during this time.
Gram staining, like other types of indicators, is performed on bacteria in order to better observe them under a microscope. Depending on the cell wall that surrounds them, they stain differently. Those that do not stain are called Gram-negative bacteria, whose wall is thinner than Gram-positive bacteria, with a greater number of layers covering them. This procedure makes it possible to determine which antibiotic is appropriate, as well as its efficacy. The resulting antibiotic must be able to pass through bacterial walls, depending on whether the bacterium is Gram-negative or Gram-positive.
The steps that must be followed to obtain a successful Gram stain are simple. First, the sample is collected using a swab. The sample is then spread on a slide and allowed to dry. Then, with the help of alcohol, the sample is fixated, after which the stain – in this case violet – is applied, and the stain is applied for about one minute. To continue the process, the sample is rinsed with water and lugol is applied. This solution is then capable of penetrating the wall of the micro-organism. After a few seconds, the slide should be washed again with a mixture of acetone and alcohol.
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In conclusion, laboratory indicators and microbiology play a decisive role in the treatment of infectious diseases. By enabling the diagnosis of harmful agents, the right method must be practised to obtain the solution sought. These are elementary tools of universal use, thanks to which it is possible to find the most accurate treatment possible.
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