Bacteria, viruses, fungi

Bacteria, viruses, fungi?

Infections can occur through various pathogens in all people. One differentiates between different types of pathogen, the most important ones are bacteria, viruses and fungi.




Bacteria are small, one celled organisms. The human body is populated by several types of bacteria. Bowel bacteria and bacteria on the skin carry out important tasks. Other types of bacteria can cause illnesses. Also if useful bacteria find their way to parts of the body where they don’t belong, they can cause symptoms of illness: Urine infections, for example are often caused by bowel bacteria and skin bacteria sometimes find their way into the bloodstream through wounds after operations.

Medicines that are effective in treating bacteria are called antibiotics.




Viruses are parasites that multiply in organic cells. They have no metabolism of their own. Many healthy people are infected by viruses but do not become ill because their immune systems have the viruses “under control”. These included viruses like herpes virus, the cytomegalo virus and polyomavirus

Antivirals are medicines which are used to treat viruses. As the various types of viruses are differently constructed, a unique antiviral has to be developed for each type. Unfortunately this is not always successful.




Fungi are organisms consisting of one or multiple cells. In contrast to plants, they cannot create organic substances themselves and therefore exploit the organic substances created by other organisms. Fungi are very important decomposer of dead organic material (e.g. to create humus). A limited number of fungi types can afflict the human body and provoke symptoms of disease. These include, for example, various candidemia and aspergillus varieties. Candida albicans can, for example, cause infection of the upper cavity of the mouth and the upper region of the throat (“thrush”). Aspergillus can cause a lung infection. Also, pneumocystis jirovecii are now categorised as fungi – this is a germ which, by immunosuppressed patients, can lead to pneumonia.



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