1.1- Intro to Microbiology

$1.1$ Overview of Microbiology

• Microbiology: The study of microbes.

  • Microbes: Encompass cellular, living microorganisms (bacteria, archaea, fungi, protists, and helminths) and nonliving/noncellular entities (viruses and prions).

Cell Characteristics and Origins

1. Prokaryotic Cells

   • Single-celled organisms that lack a true nucleus and membrane-bound organelles.

   • Typically categorized into two domains: Bacteria and Archaea.

2. Eukaryotic Cells

   • Complex cells contain a true nucleus and various membrane-bound organelles.

   • It can be unicellular or multicellular.

   • Kingdoms include: Animalia, Plantae, Fungi, and Protista.

3. Endosymbiotic Theory: A theory stating that eukaryotic cells evolved from prokaryotic cells.

Pathogens and Disease

• Pathogens: Microbes that cause disease.

  • True Pathogens: Pathogens that can cause disease in healthy individuals.

  • Opportunistic Pathogens: Generally do not cause disease in healthy hosts but lead to infections in individuals with weakened immune systems.

• Germ Theory of Disease: States that microbes cause infectious diseases.

  • Etiological Agent: The causative agent of a disease.

Historical Development

• Robert Hooke: Used crude microscopes to publish early descriptions of cells.

• Antonie van Leeuwenhoek: He refined microscope designs and was the first to observe bacteria.

• Debate on Life's Origin

  • Spontaneous Generation: The idea that life comes from nonliving items.

  • Biogenesis: The idea that life emerges from existing life.

  • Francesco Redi: Performed experiments to test the hypothesis of spontaneous generation.

  • Louis Pasteur: Proved biogenesis is responsible for the propagation of life.

  • Proved yeast performs fermentation.

  • Developed vaccines for anthrax and rabies.

  • Demonstrated that airborne microbes cause spoilage and disease, leading to the development of aseptic techniques.

Validating Germ Theory

• Robert Koch: Reinforced the germ theory and developed techniques to isolate bacteria. He discovered that anthrax is caused by a bacterium.

• Koch’s Postulates: $4$ principles used to identify the causative agent of a disease:

  1. The same organism must be present in every case of the disease.

  2. The organism must be isolated from the diseased host and grown as a pure culture.

  3. The isolated organism should cause the disease when introduced into a susceptible host.

  4. The organism must be re-isolated from the inoculated, diseased animal.

Aseptic Techniques in Medicine

• Aseptic Techniques: Methods used to maintain sterile environments and prevent Healthcare-Acquired Infections (HAIs), such as nosocomial infections.

• Ignaz Semmelweis: First to develop aseptic techniques in the 1840s, recommending handwashing to lower childbed fever rates.

• Joseph Lister: Investigated aseptic surgery and used carbolic acid as a cleaning agent.

• Florence Nightingale: Established the use of aseptic techniques in nursing practices.

The Scientific Method

• Process: Starts with a question, followed by a hypothesis (prediction), then observation, and finally a conclusion derived from data.

• Scientific Law: A precise statement of fact.

• Scientific Theory: A hypothesis that has been extensively proven and supported.