Causative agents of infectious diseases include bacteria, Rickettsia, Chlamydia, My-coplasma, protozoa, fungi, viruses, prions. We distinguish diseases caused by protozoa, worms, insects and mites, which are referred to as invasive, or parasitic diseases. The pathogenesis of an infectious disease reflects the main stages of the infectious process development.
The goal of treating an infectious process is elimination of the cause (causative agent) or blocking the mechanism of infectious disease development.
Chemotherapeutic agents characterized by a targeted selective effect on pathogens and having low toxicity for humans are used inetio-tropic therapy.
According to the spectrum of their activity chemotherapeutic drugs are identified as follows:
• antibacterial;
• antimycotic;
• antiviral;
• antiprotozoal;
• anthelmintic.
Antibacterial chemotherapeutic drugs:
• antibiotics;
• synthetic antibacterial drugs;
• antisyphilitics;
• anti-tubercular drugs.
Antibiotics are chemotherapeutic substances of biological origin that selectively inhibit the vital activity of microorganisms either by stopping their growth or by causing their death.
Antibiotics are classified in a variety of ways.
Depending on the source of their isolation, antibiotics are divided in two groups:
• natural (biosynthetic) antibiotics are waste products of microorganisms and lower fungi;
• semi-synthetic antibiotics are chemical derivatives of natural antibiotics, obtained by chemical synthesis.
The following groups of antibiotics are identified regarding their chemical structure (fig. 17.1):
• в-lactam antibiotics (penicillins, cephalo-sporins, carbapenems, monobactams);