Biol 3230 Unit 1_ What is Microbiology and Why Does it Matter_ - Students

Chapter 1: What is Microbiology and Why Does it Matter?

Definition of Microbiology

  • The study of small living organisms (microorganisms).

    • Micro: meaning small or "teeny-tiny".

    • Biology: study of living things.

  • Microorganisms can be unicellular (single-celled) or multicellular (e.g., worms and kelp).

Relative Sizes of Microorganisms

  • Categories of Microorganisms:

    • Acellular: Prions and viruses.

    • Cellular:

      • Bacteria/archaeans (1000 nm).

      • Eukaryotes (10,000 nm, e.g., fungi, protozoa, helminths).

Importance of Microbiology

Relevance in Today's World

  • Microbiology is increasingly relevant due to its impact on:

    • Infectious diseases as leading health and socioeconomic issues.

    • Particularly concerns in elderly populations and developing countries.

    • Daily life aspects such as food production, sewage treatment, and air quality.

Health Care Implications

  • Approx. 50% of health issues linked to infectious diseases.

  • Majority of these diseases caused by viruses (common cold, influenza, COVID-19) limit treatment options.

  • Direct hospital costs to combat infectious diseases exceed $4.8 billion annually.

  • Over 2 million nosocomial infections (hospital-acquired infections) annually.

Overcoming Infectious Diseases

  • Historical difficulties in treating and preventing diseases until recent advancements:

    • Discovery of antibiotics (e.g., Penicillin by Alexander Fleming in 1928).

    • Vaccinations (first true vaccination against smallpox in 1796).

    • Improved sanitation led to reduced incidence of infectious diseases (e.g., chlorination of drinking water).

Reemergence of Diseases

  • Diseases previously thought to be conquered are reemerging due to factors including:

    • Antibiotic resistance.

    • Emergence of new diseases and the recognition of previously harmless organisms as pathogens.

    • Increased interest in bioterrorism.

Antibiotic Resistance

Trends in Antibiotic Resistance

  • Overuse and misuse of antibiotics contribute to resistance:

    • Over-prescription for viral infections.

    • Antibiotics used in livestock.

    • Patients often do not complete prescribed antibiotic courses.

  • Evolutionary pressures lead to bacteria developing resistance.

Global Antibiotic Usage

  • Low- and lower-middle-income countries account for significant antibiotic usage compared to high-income nations.

Pathogen Classification

Types of Pathogens

  • Primary (obligate) pathogens: Cause disease in healthy hosts (e.g., Yersinia pestis).

  • Accidental pathogens: Uncommon near humans but can cause disease (e.g., Clostridium tetani).

  • Opportunistic pathogens: Generally do not cause disease unless host is compromised (e.g., Candida albicans).

Factors of Pathogenesis

  • Understanding disease development through epidemiology, pathogenesis, and host defense.

Epidemiology

  • Focuses on how diseases spread and the requirements for infection:

    • Entry, establishment, host defense defeat, damage to the host, and transmissibility.

  • Classifies pathogens by transmission routes (air, food, vectors, person-to-person).

Pathogenesis

  • Studies how diseases develop and why specific bacteria cause different diseases.

  • Includes the sequence of infection from contact to symptom manifestation.

  • Virulence factors influence the severity of the disease:

    • Involves infectivity and severity of symptoms.

Host Defenses

  • Innate immunity (nonspecific) vs. adaptive immunity (specific).

  • Successful pathogens evade host defenses through various mechanisms like camouflage and direct attack on immune cells.

Treatment of Infectious Diseases

Strategies for Treatment

  • Antibiotics: Kill pathogens selectively without harming the host.

  • Disinfectants vs. Antiseptics: Disinfectants for surfaces; antiseptics for living tissues.

Prevention and Immunization

  • Prevention is more effective than treatment, involving public health measures and immunization:

    • Disinfection of water supplies, monitoring food, hygiene, and sanitation.

  • Immunization efforts must ensure vaccine safety and efficacy.