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Microbes are unseen organisms, simple in construction and usually unicellular. We can't see them with naked eye as their size is smaller than 0,1mm. Many micro-organisms compose the natural flora of the human and they can become, under specific circumstances, pathogenic. A part from the micro-organisms of the natural flora of humans there are around us millions of other organisms. The intrusion of these pathogenic micro-organisms to the organism of the human is called contamination, while their installation and their multiplication inside the organism are called infection. The diseases, which are caused by pathogenic micro-organisms, are called infectious.
Many bacteria threaten our health via the substances they produce. These substances are called toxins and are distinguished to endotoxins and exotoxins. The pathogenic micro-organisms are transmitted to the human by food, water, contact with contaminated animals, trickles of cough, by direct contact with contaminated humans and finally by the indirect contact with objects which have been used by these humans. They usually enter our organism from a discontinuity of the skin or from mucomembranous which are in some organs such as mouth, stomach and vagina.
Antibiotics are chemical substances with antimicrobiological effect, which are produced by bacteria, fungus and plants which act by stopping or obstructing a special industrial reaction of the micro-organisms.
The dealing with the micro-organisms can be achieved with the use of these medicines, which either stop the development of the microbes or they just kill them and they are distinguished to 1.antibiotics, which stop the structure of the cell τοιχώματος, 2.antibiotics, which stop the structure of the proteins of a microbe, 3.antibiotics, which act against the cells' membrane and 4.antibiotics, which act against the structure of DNA.
The history of Microbiology starts in the middle of the 17th century when the Dutchman, Antony van Leeuwenhoek (1632-1732) with the primitive microscopes, which he made by himself, observed living microbes, which he described and designed.
The real importance of microbes for the economy of the nature and the pathology of human was proved by the French chemist Louis Pasteur (1822-1895). In 1876 the German Robert Koch proved that, a Bacil was the reason for the disease of anthrax.
In 1882 he studied tuberculosis in humans and in a short period of time he described the bacterium of tuberculosis which is known as Koch's bacterium. He also formulated the requirements which are called Koch's criteria. According to these criteria a disease is caused by a pathogenic micro-organisms when this micro-organism: 1) is detected in the tissues or the fluids of an ill person or in the organism of human, who died from this disease 2) can be isolated and cultivated in the laboratory 3) can cause the same disease to guinea-pigs but it can also be isolated from them again. An accidental historic discovery happened in 1928 by Sir Alexander Fleming when he noticed the infection of a cultivation of a staphylococcus in the agar of a disk from the fungus, Penicillium notatum, which caused the disappearance of the colonies of staphylococcus round the mould of the fungus.
The studies which followed were completed in 1940 with the isolation of penicillin.
Within a few years its production start in the USA from cultivations in tanks of thousands of liter of nutritious solutions, while its use during the Second World War decreased the causalities of the allies.
In 1945 he won the Nobel for Medicine. It must also be noted that Fleming has seen the bad side of his antibiotic as in 1946 he said that giving penicillin, even in small installments, can lead to the development of resistant microbes.
The resistance of the micro-organisms isn't a new phenomenon. Since antimicrobic therapy was used, namely with penicillin in 1940, the satisfaction for the discovery of a new substance followed the disappointment for the appearance of resistant to it. The ability of microbes to resist against the agency of the antimicrobic substances was first recognized by Ehrilch in 1914 and was called Arzeitestigkeit, which means fortification against antibiotics. The first mechanism of resistance was recorded in 1940 by Abraham and Chain, who isolated in colobacterium, an enzyme able to hydrolyze penicillin. With the use of penicillin in 1941 less than 1% of the hospital microbes were resistant; in 1947 they increased to 38% while today sixty years after the discovery of penicillin the rate goes up to 80%.
The number of the resistant pathogenic increases at a very quick pace, while the discovery and the preparation of new antimicrobics failed because of the cost of the research (every new antibiotic costs about 100-350 million dollars).
Resistance until now is revealed to all of the antimicrobic substances, a lot of pathogenic reveal resistance to lots of antibiotics resulting to an increase of the clinical problems, which are caused by these micro-organisms.
The resistant strain of a micro-organism can be prescribed either as the resistance to a specific number of antimicrobic substances or as the resistant strain to two or more antibiotics, which are usually dedicated. Resistance is the result of change in the structure of the cell's DNA. The change happens with transmutation or with transmission. During the transmutation a lot of inversions, duplicities, additions of nucleides, lack or shift of big parts of DNA happen.
The transmission of DNA happens with the coupling of plasmidius, which compose the most important ''device'' of transmission the resistance to the clinical strains, with transportation, namely with transfer of DNA via the bacterium, and finally with transformation of DNA.
From the industrial point resistance can be expressed with the production of an enzyme, which can invert the antibiotics. The most famous are b-lactamases and aminoglicocides. This mechanism of resistance is the most usual.
The antibiotics mustn't be used without a serious reason or for the therapy of non serious inflections. The protective grant of antibiotics must be applied only in specific cases.
The existence of antibiotics can lead to the neglect of the loyal and scholastic application of the sterilization in the operating-table and the hospital. The therapy with antibiotics can be applied under clear clinical microbiological diagnosis of the disease. It is possible that the therapy can start after the receiving and the dispatching of the execution cultivations and trials of sensitivity of the microbe.
Today what must be aimed at is on the one hand every possible effort for the prevention of the disease and on the other hand the discovery of ways of using antibiotics, so the appearance of resistance be reduced and the attainment of an effective therapy to the diseases caused by micro-organisms, be achieved.
The resistance in Europe and especially in Greece has reached dangerous levels and so many patients in hospitals are really in danger because all the antibiotics can't deal anymore with these resistant micro-organisms. This thing really bothers the community and within a short period of time measures have to be taken, which might limit the pointless use of antibiotics.
Microbiology and Anosobiology, J. K. Papapanagiotou, ed. Paratiritis, pages 13-15, 1994
Microbiological Chronicles, Official Journal of the Microbiology Society of Thessaloniki, Volume 13, Microbiological resistance, O.Babatsi-Manou, pages 91-95, 1997
Biology of the third class of high school, pages 23-26, 2006