Groups and main characteristics of microorganisms belonging to medical microbiology. The main roles of microorganisms. Basic concepts related to pathogenicity and virulence.

Louis Pasteur

Microbiology is the science of microbes, organisms too small to be seen by unaided eyes

Types of Microorganisms

Subcellular
Cellular
Multicellular

Subcellular

Viruses
Viroids
Prions

Cellular

• Prokaryotes: archaea, bacteria
• Eukaryotes: unicellular fungi,
• Protists: protozoa, algae

Multicellular

• Helminths and ectoparasites (can be classified among infectious agents of medical microbiology)

Microbes characteristics

yes

Relative sizes

yesss

The domains of life

• Eubacteria: Unicellular, prokaryotic

• Plantae: Multicellular, eukaryotic

• Protista: Eukaryotic, uni and multicellular

• Archaebacteria: Unicellular, prokaryotic

• Animalia: Multicellular, eukaryotic

• Fungi: Multicellular, eukaryotic

The role of microorganisms

• The biogeochemical cycle of chemical elements
• The production of food and pharmaceuticals, as well as biotechnological products
• Microbes are capable of living in beneficial interactions with the host organism (microbiota, microbiome →)
• They can cause diseases (pathogens, pathogenicity →)

microbiome

the community of microbes—bacteria, archaea, eukaryotic microbes (e.g., fungi), and viruses—living in a given environment, together with the environment they inhabit. In contrast, the term microbiota refers exclusively to the microbes themselves