MICP Prelims

• Pathogen: disease-causing agents
• Aerobes: microbes that need oxygen

  Anaerobes: microbes that do not need oxygen
• Microbiology includes the study of:

  • Virus
  • Fungus
  • Bacteria
  • Protozoa
  • Algae
• Categories of Microbes:

  • Acellular microbes = infectious particles (viruses, prions)
  • Cellular Microbes = microorganisms (bacteria, archaea, protozoa, algae, fungi)
  • Pathogens = microbes that cause diseases (aka germs or infectious diseases)
  • Nonpathogens = microbes that do not cause disease
  • Indigenous microbiota = microbes that live on and in the human body (Normal Flora)
  • Opportunistic pathogens = have potential to cause a disease under ordinary conditions (Escherichia Coli)
• • 1867: Robert Koch established Koch's postulate, the Germ Theory of Disease
  • 1884: Hans Christian Gram developed the Gram stain technique for classifying germs
  • 1887: Richard Petri developed the Petri dish for growing microbial cultures
  • 1910: Paul Ehrlich discovered Salvarsan, an antibiotic for Syphilis
  • 1928: Alexander Fleming discovered Penicillin antibiotic from mold
  • 1930: Introduction of Electron microscopy
  • 1940 and 1950: Development of Vaccines
• Fields of Study in Microbiology:

  • Virology- virus
  • Bacteriology- bacteria
  • Mycology- fungi
  • Protozoology- protozoa
  • Phycology- algae
• Virus: size 20-300 nm, shapes include spheres, rods, bullets, bricks, nucleic acids DNA and RNA, outer covering made of capsid
• Evolution of Microbiology:

  • 1600: Robert Hooke discovered the microscope and the "Cell Theory" as the basic unit of living organisms
  • 1670: Anton Von Leeuwenhoek observed bacteria, protozoa, and fungi, known as the Father of Microbiology and Protozoology
  • 1796: Edward Jenner discovered the smallpox vaccine
  • 1800: Louis Pasteur introduced Pasteurization and Fermentation Theory
  • 1840: Ignaz Philip Semmelweis implemented antiseptic procedures to prevent childbirth fever
  • 1860: Joseph Lister introduced aseptic surgery
• Types of Cells:

  • Prokaryotic Cells
  • Eukaryotic Cells
• • Protozoa: eukaryotic cell, outer covering made of pellicle, possess both DNA and RNA, unicellular organisms, reproduction through binary fission, morphologic forms include cysts and trophozoites
  • Algae: eukaryotic cell, outer covering made of cellulose, plant-like with chlorophyll for photosynthesis, no true roots, stems, and leaves, vary in size from single-celled phytoplankton to large seaweeds
• Diatoms:

  • Unicellular algae
  • Inhabit both fresh and saltwater
  • Cell wall contains silicon dioxide
  • Utilized in filtration systems, insulation, and abrasives
• Bacterial:

  • Prokaryote
  • No true nucleus
  • No organelles
  • Divide: binary fission
• Major Components of bacteria:

  • Outer envelope
  • Cell membrane
  • Internal structures
• Bacteria is classified based on shape:

  • Spheres (cocci)
  • Rods (bacilli)
  • Spirals
• Envelope Structure for protection from harsh environmental conditions
• Cell Wall:

  • A.k.a murein sacculus
  • Principal component is peptidoglycan
  • Multi-layered in G(+) bacteria
  • Single-layered in G(-) bacteria
• Special Components of G(+) Cell Walls:

  • Teichoic acids: major surface antigens, provide tensile strength
  • Polysaccharides: neutral and acidic sugars
• Special Components of G(-) Cell Walls:

  • Outer Membrane: bi-layered structure with lipopolysaccharide (LPS)
  • Lipoprotein: connects peptidoglycan to outer membrane
• Projecting Structures:

  • Flagella
  • - Lophotrichous: tuft of flagella at one end
  • - Amphitrichous: single flagellum at both end
  • - Peritrichous: flagella surrounding the bacterium
  • - Monotrichous: only one flagellum
  • - Atrichous: lacks flagella
  • Pili or Fimbrae:
  • - Common Pili: for attachment
  • - Sex Pili: for gene exchange
  • Axial Filaments: help propel spirochetes forward
• Cytoplasmic Membrane/ Cell Membrane: functional analogue of mitochondria, site of ATP production
• Internal Structures:

  • Nucleoid: packaging of genetic material
  • Endospores: enable bacteria to withstand adverse environmental conditions
  • Mesosomes: play a role in cell division
  • Inclusion Bodies/Granules: for food storage
• Nutritional Requirements:

  • Carbon: structural backbone of organic molecules
  • Nitrogen, sulfur, phosphorus
  • Inorganic ions
  • Growth factors
• Energy Source:

  • Sunlight
  • Oxidation of inorganic substances
• Physical Requirements of Bacteria:

  • Moisture
  • Oxygen: Aerobes, Anaerobes, Facultative, Microaerophiles, Capnophiles
  • Temperature: Psychrophiles, Mesophiles, Thermophiles, Hyperthermophiles
  • pH: Acidophiles, Neutrophiles, Alkalophiles
  • Osmotic Conditions: Osmophiles, Halophiles
• Most medically important bacteria are:

  • Facultative
  • Mesophiles
  • Neutrophiles
• Stages of Bacterial Growth:

  • Lag phase: adapt to nutrients, synthesize enzymes, prepare for cell division, 1-4 hours
  • Log phase: active growth, brief, 8 hours
  • Stationary Phase: culture is at its greatest population density, death=growth rate
  • Death or Decline Phase: nutrients consumed, number of death>number of living
• • Bacteria: prokaryotic cell, outer covering is cell wall made up of peptidoglycan, possess both DNA and RNA, nucleoid, smaller ribosomes, lacks mitochondria
• • Fungi: eukaryotic cell, outer covering made of chitin, cell membrane made of ergosterol, possess both DNA and RNA, true nucleus, nuclear membrane, mitochondria, larger ribosomes
• Dinoflagellates- Unicellular algae; Produces powerful neurotoxin
• MICROORGANISMS- study of MICROORGANISM /MICROBES
• Gram-negative bacteria = Escherichia coli

  Gram-positive bacteria = staphylococcus aureus

  Acid-fast bacteria w/ lipid rich cell wall = Mycobacterium tuberculosis

  Bacteria w/o cell wall = Mycoplasma
• Glycocalyx is also known as:

  Capsule -if strongly attached to the cell wall; protects against phagocytosis

  Slime Layer -if loosely attached to the cell wall; mediate attachment to sites
• Capsule

  • Virulence- harmfulness “the capsule makes the bacteria virulence”

  • Antiphagocytosis- evasion from ingestion

  • Antigenic- stimulates an antibody response

  • Protects from dehydration
• Growth

  -increase in the number of cells
• Based on carbon source of bacteria:

  • autotrophs (lithotrophs)- Utilize inorganic compounds for their carbon source.
  • heterotrophs (organotrophs)- Utilize organic compounds for their carbon source.
• Oxygen classification of bacteria

  • Aerobes- require oxygen
  • Anaerobes- cannot survive in the presence of oxygen
  • Facultative- can grow in the presence/absence of oxygen
  • +Microaerophiles-can grow under low oxygen tension but their rate of growth is diminished
  • +Capnophiles- require the addition of carbon dioxide to enchance their growth
• Temperature classificaion of bacteria

  • Psychrophiles- organisms which grow best at 10- 20C -
  • Mesophiles- organisms which grow best at 20- 40C
  • Thermophiles- organisms which grow temperature above 40-60C
  • Hyperthermophiles- organisms which grow best at >100C
• pH classification on bacteria

  • Acidophiles- organisms that grow at a low pH (<6.0)
  • Neutrophiles- organisms that grow at a neutral pH (7.0-7.2)
  • Alkalophiles- organisms that grow at a high pH (8.4-9.0)
• Osmotic Condition classification on bacteria

  • Osmophiles- organisms that need high osmotic pressure for maximal growth
  • Halophiles- organisms that require salt for growth
• a microscope that contains more than one magnifying lens

  compound microscope