INTRODUCTION
Manual of Practical Exercises in Medical Microbiology - Part II
Microorganisms - bacteria, viruses, fungi and protozoa colonize all ecological niches in nature. A number of them known as saprophytes they live freely in soil and water, participating in the cycle of substances in nature. Others have adapted to develop in humans, animals and plants, establishing complex relationships between them from symbiosis to parasitism.
Life on Earth, in all its dimensions, without microorganisms is impossible. From a medical point of view. a huge part of the tens of thousands of known types of microorganisms are harmless to the human organism. Bacteria and fungi that have adapted to develop on the skin and mucous membranes of the human body are harmless to a healthy organism. These 500 or so species make up its normal flora (microbiota) and play an irrevocable role in the physiological processes of the body with their antagonistic action towards other pathogenic agents, participation in metabolic processes and stimulation of the development of the immune system and the immune response during the infectious process.
Some types of microorganisms that have adapted to the human organism damage physiological processes during their development. They are known as pathogenic microorganisms and are not part of the normal flora. After infection with them, they reside temporarily in the tissues and organs. Depending on the protective reactions of the body, various forms of the infectious process take place - from inapparent (unmanifested) infection to mild and severe lethal forms of the infectious disease. Depending on their source and reservoir, a number of pathogenic microorganisms spread epidemically between humans or between animals and humans.
In individuals with weakened protective reactions (after trauma, burns, cancer and other severe chronic diseases, drug addictions) pathogenicity can also be manifested non-pathogenic microorganisms - saprophytes from the environment and more often bacteria and fungi from the normal flora, known in this capacity as opportunistic or opportunistic microorganisms. The disturbances in the balance of the species of the normal flora, known as dysbiosis, as a result of the often irrational use of antibiotics or the long-term treatment with cytostatics and immunosuppressants, to the suppression of immune reactions and manifestation of pathogenicity by the microorganisms developed in an excessively large amount.
Knowledge of the microorganisms that cause infectious diseases in humans - pathogenic and conditionally pathogenic - is of great importance for medical practice. Infectious diseases are leading in human pathology and as a cause of death. In clarifying the etiology and treatment of infectious diseases, microbiological diagnostics and knowing the possibilities of the diagnostic methods used in it are of leading importance.
The positive effect of microbiological diagnostics can be expected only if the clinical and laboratory personnel know the rules for taking and transporting the clinical material, the nature of the diagnostic methods and the assessment of the pathogenic potential of the proven microorganisms. Determining of the antibiotic sensitivity of the isolated bacteria and fungi is a guarantee for the rational use of antibiotics to limit the increasingly widespread drug resistance among infectious agents.
This manual for practical exercises in medical microbiology is intended for the students of the medical universities. The purpose of the thematic material is for students to gain knowledge about bacterial and viral pathogens and the classical and modern molecular diagnostic methods used in daily clinical practice to clarify the etiology of infections and provide guidelines for the rational use of antimicrobial drugs.