Introduction to Medical Microbiology

Study Notes

Microbiology is the study of microbes, including viruses, bacteria, fungi, and parasites
Anton van Leeuwenhoek's development of microscopes led to the discovery of "animalcules."
Otto Müller and Linnaeus classified these microbes
Henle proposed criteria for proving microbes cause disease
Koch and Pasteur confirmed microbes are responsible for specific diseases.
Ehrlich, Fleming, and Waksman discovered first antibacterial agents.
Enders cultivated viruses in cell cultures, enabling widespread vaccine production.
Microbiology is undergoing transformation due to advances in genome analysis, especially the Human Genome Project.

Viruses are the smallest infectious agents, ranging from 18-600 nanometers
They contain either DNA or RNA, but not both.
Viruses require host cells for replication.
Infection can result in rapid cell destruction or a long-term, latent state.
Viruses cause a wide range of diseases from the common cold to severe conditions like AIDS and Ebola.
Over 650 types of viruses that affect humans and animals have been identified.

Bacteria are prokaryotic, unicellular organisms.
They lack a nuclear membrane, mitochondria, and other organelles.
Distinguished by cell wall structure: Gram-positive (thick peptidoglycan) and Gram-negative (thin peptidoglycan).
Bacteria found in the human body, air, water, and food, some potentially causing disease.
Diseases arise from toxin production or invasion of tissues.
Many types of bacteria can cause disease, as well as a variety of manifestations of disease symptoms

Fungi are eukaryotic organisms.
They have a well-defined nucleus, mitochondria, Golgi bodies, and an endoplasmic reticulum.
Fungi exist in unicellular (yeast) or filamentous (mold) forms.
Some fungi are dimorphic (changing forms)

Microbes are important for understanding diseases.
Certain microorganisms are associated with very specific diseases, such as tetanus caused by Clostridium tetani.
Many organisms cause multiple diseases or several organisms cause the same disease.
Infections are classified as exogenous or endogenous.
Infectious disease outcome depends on the microbe's virulence, the site of exposure, and host response.

Laboratory tests are crucial for diagnosis and management of infections.
Collected samples should be representative for accurate testing.
Contamination during collection can produce inaccurate results
Antimicrobial susceptibility testing is important but needs careful selection, and results are influenced by factors outside the lab.

Microbiology is a dynamic field, with constant discoveries about microbes and their role in health and disease.

The human body is colonized by a complex community of microbes (microbiome) from birth.
The microbiome plays a role in metabolic and immunologic functions in the body.
The Human Microbiome Project helped reveal the complexity.
The "core microbiome" is shared across many individuals.
Alterations in microbiome, termed dysbiosis, can cause diseases.
Microbiome shifts in the body's different areas can indicate disease risks.
Probiotics are mixtures of bacteria that are believed to provide benefits to the host.