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staphylococcus aureus, bacterial colonies on agar

The detection of micro-organisms accounts for a major part of the work in the laboratories of clinical bacteriology. These centres focus on detecting bacteria in, e.g., swabs from the throat, faeces, wounds, urine and other material. The aim is to ensure optimum growth conditions for bacteria or other micro-organisms, to isolate them from a mixture of cultivated organisms, and to identify those whose presence might relate to the given health condition of a patient. For this purpose cultivation media are used where the growth of bacteria leads to the formation of colonies.

bacterial colonies on agar bacterial colonies on agar bacterial colonies on agar bacterial colonies on agar

In an ideal case, a colony originates from one bacterium and is composed of several dozens up to hundreds of millions of cells. Based on the colonies’ appearance it is often possible to establish the genus or at least the group of bacterial genera concerned in the given case with help of a few additional tests. The character of a grown culture together with the judgement of the microscopic appearance of bacterial cells provide precious information which determines the further course of identification.

Colonies of pneumococci on agar Colonies of Mycobacterium tuberculosis on agar Colonies of Neisseria meningitidis on agar Colonies of Haemophilus influenzae on agar

From the point of view of a laboratory of clinical microbiology, a photograph may become useful documentary material. Photographs may be also very helpful in teaching microbiology, in which a number of laboratories take part. Just a few pictures may provide a clear comparison between the growth properties of closely related species , reveal a different character of bacterial growth on various types of media, and intra-species variability. This is useful in cases where the best possible verbal description would provide only an incomplete, framework idea. Photographs may thus be used to acquaint students with a number of phenomena whose origin rests in the structure of bacterial cells and in their metabolic and genetic properties.

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