Microbiology and Public Health Preparation Notes

Classification of Life

  • Life can be categorized into various domains and kingdoms based on cellular organization, metabolic processes, and environmental adaptations.

Prokaryotic vs Eukaryotic Cells

  • Prokaryotic Cells: Simple, unicellular organisms without a nucleus; e.g. bacteria.
  • Eukaryotic Cells: More complex organisms with a nucleus and organelles; e.g. plants, animals, fungi.

Bacterial Structure

  • Ribosomes: Bacterial ribosomes (70S) are different from eukaryotic ribosomes (80S); many antibiotics target these ribosomes to inhibit protein synthesis.
  • Cell Envelope:
    • Gram-positive Bacteria: Thick peptidoglycan layer, teichoic acids, polysaccharides.
    • Gram-negative Bacteria: Thin peptidoglycan layer surrounded by an outer membrane.

Bacterial Structures

  • Nucleus: Contains circular, supercoiled, double-stranded DNA, proteins, and RNA.
  • Plasmids: Small, circular DNA that can replicate independently and carry resistance genes.
  • Flagella: Tail-like structures for movement; have antigenic properties.
  • Pili (Fimbriae): Surface appendages for attachment, composed of pilin protein.

Bacterial Growth

  • Growth Curve Phases:
    • Lag Phase: Bacteria adapt to the environment.
    • Exponential Phase: Rapid growth and division; antibiotics are most effective.
    • Stationary Phase: Nutrient depletion and waste accumulation lead to a plateau in growth.
    • Death Phase: More bacteria die than are produced.

Oxygen Requirements

  • Obligate Aerobes: Require oxygen for growth.
  • Obligate Anaerobes: Only grow in absence of oxygen.
  • Facultative Anaerobes: Prefer oxygen but can grow without it.
  • Aerotolerant Anaerobes: Can survive with or without oxygen.
  • Microaerophiles: Require a minimum level of oxygen.

Culture/Growth Media Types

  • Based on Consistency:
    • Solid Media: Contains agar (1.5-2%).
    • Semi-solid Media: Contains less agar (0.5%).
    • Liquid Media: No agar.
  • Based on Purpose:
    • General Media: Nutrient broth, peptone water.
    • Enriched Media: Enhanced nutrient content.
    • Selective Media: Allows growth of specific organisms while inhibiting others.

Hemolysis Types in Bacterial Growth Media

  1. Complete Hemolysis (Beta): Clear; e.g. Streptococcus pyogenes.
  2. Partial Hemolysis (Alpha): Green; e.g. Streptococcus pneumoniae.
  3. Gamma Hemolysis: No change; e.g. Enterococcus faecalis.

Examples of Selective Growth Media

  • MacConkey Agar: Selective for Gram-negative bacteria; lactose fermenters turn pink.
  • Bile Esculin Agar: Identifies Group D Streptococci.
  • Mannitol Salt Agar: Selective for Staphylococcus aureus.

Gram Positive Bacteria

  • Staphylococcus aureus: Common skin infection causing organism, found in anterior nares.
  • Staphylococcus epidermidis: Normal flora; can cause infections with medical devices.
  • Streptococcus pyogenes (Group A): Causes strep throat and skin infections.

Gram Negative Bacteria

  • Salmonella typhi: Causes typhoid fever.
  • Escherichia coli (E. coli): Common in urinary tract infections.
  • Vibrio cholerae: Causes cholera.

Immunology Basics

  • Immunity Types:
    • Innate Immunity: First line of defense, non-specific.
    • Adaptive Immunity: Slower response, highly specific.
  • Hyperensitivity Disorders: Various types from allergies to autoimmune diseases.

Epidemiology Overview

  • Distribution and Determinants of Diseases: Understanding the occurrence and spread of diseases in populations.

Public Health Essentials

  • Roles of Department of Health (DOH): Leadership, enabling health capacities, and service administration.

Population Health Concepts

  • Life Expectancy: Average expected lifespan.
  • Morbidity and Mortality: Measures of health and disease within populations.

Occupational Health & Safety

  • Focus on preventing workplace health risks to maintain a safe working environment.

Public Health Programs

  • Ottawa Charter for Health Promotion: Framework for health promotion initiatives.

Immunization Programs

  • Republic Act No. 10152: Legislation for mandatory health immunizations for infants and children.

Health Promotion and Awareness

  • Monthly health awareness events addressing various health issues including cancer, mental health, and disease prevention.