The bacteria learnt to develop resistance to antibiotics long before people began using these agents in the medical practice. The point is that antibiotics release various microorganisms as a weapon in the struggle for existence. Bacteria come across these substances all the time, and for the billions of years of evolution they learnt to adapt to them.
It is known that the bacteria can pass exchange the genes providing protection from antibiotics, for example, the genes encoding the molecular pumps, removing the antibiotic from the cell, or enzymes destroying the antibiotic. However the resistance to antibiotic can develop spontaneously – as a result of mutations in the bacterial genes, with the subsequent natural selection of successful variants. In this case it’s important for the bacteria that the concentration of the antibiotic in the medium was not too high – in this case, the chances of survival for the antibiotic-resistant mutants go up.
Therefore, development of antibiotic resistance in bacteria is an inevitable natural process. However, it’s important to realize that it is boosted by irrational application of antibiotics: too frequent unreasonable prescription of antibiotics in case of viral infections (when antibiotics are inefficient), preventive administration of antibiotics, self-treatment with antibiotics, non-observance of recommendations for use, and uncontrolled use of these agents in the agriculture.
Every administration of antibiotics bears a risk of resistant strains development. And this risk is especially high in case of improper use of the antibacterial agents: decrease of doses and treatment course, violation of dosage regimen. In these cases a person creates all the necessary conditions for selection of bacteria resistant to antibiotics. The latter in their turn bring problems not only to their first host: they easily spread among the humans and animals through food, water, dirty hands, disperse by the wind with the dust, and are transmitted by flies.