Medical microbiology

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Medical microbiology

• CLS 212

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Introduction

• What is microbiology?
• the branch of biology that studies
  microorganisms and their effects on humans
• Microorganisms
• a collection of organisms that share the
  characteristic of being visible only with a
  microscope
• contribute to the quality of human life
• o maintain the balance of chemical
  elements in nature
• o breakdown the remains of all that die
• o recycle carbon, nitrogen, sulfur,
  phosphorus and other elements
• some cause infectious disease called Pathogenic
• o overwhelm body systems by sheer force
  of numbers
• o produce powerful toxins that interfere
  with body physiology
• o viruses inflict damage by replicating
  themselves within tissue cells causing tissue
  degeneration

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Classification of Microorganisms

• Taxonomy - the science of classification
• Kingdom (5 major divisions)
• Phylum (groups of related Classes)
• Class (groups of related Orders)
• Order (groups of related Families)
• Family (groups of related Genera)
• Genus (groups of related Species)
• Species (living organisms that are alike)
• The Five Kingdoms
• 1. Monera (unicellular prokaryotes bacteria,
• cyanobacteria, blue-green
  algae)
• 2. Protista (unicellular eukaryotes
  protozoa,
• unicellular algae, slime
  molds)
• 3. Fungi (multicellular eukaryotes molds,
  mushrooms, yeasts)
• 4. Plantae (multicellular eukaryotes plants)
• 5. Animalia (multicellular eukaryotes
  animals)

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Classification of Microorganisms

• Microorganisms and all other living organisms are
  classified as Prokaryotes and Eukaryotes. They
  are distinguished on the basis of their cellular
  characteristics.
• Prokaryotes and Eukaryotes
• ?? enclosed by cell (plasma)
  membranes
• ?? use DNA for genetic information
• Prokaryotes
• ?? lack a nucleus
• ?? lack organelles
• ?? include bacteria and
  cyanobacteria (blue-green algae)
• Eukaryotes
• ?? have a nucleus
• ?? have organelles
• ?? include fungi, protozoa and
  simple algae
• Viruses
• ?? are neither Prokaryotes or
  Eukaryotes
• ?? lack the characteristics of
  living things
• ?? are able to replicate only in
  their host (living cells)

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Prokaryotic Cell Eukaryotic Cell
All bacteria All animals and protozoa Biological distribution
Absent Presents Nuclear membrane
Generally absents Presents Membranous structures other than cell membrane
70s 80s Cytoplasmic ribosome's (density)
Present (complex chemical constitution) Absent Cell wall
Composed of DNA only Composed of DNA and Proteins Chromosomes
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Historical Background

• mid 1600s English scientist Robert Hooke viewed
  cells and observed strands of fungi
• 1670s Dutch merchant Anton van Leeuwenhook made
  a simple one-lens microscope and observed and
  provided accurate descriptions of protozoa, fungi
  and bacteria
• 1750-1760 Carolus Linnaeus classified all known
  plants and animals and set down rules for
  classification
• 1875-1900 The Golden Age of Microbiology

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Historical Theories

• The Theory of Spontaneous Generation
• a long-held theory that life springs up from
  non-living or decaying organic matter, was based
  on observations of rotting food seemingly
  producing living organisms. Francesco Redi
  (1626-1678) was an Italian physician who showed
  that rotting meat carefully kept from flies will
  not spontaneously produce maggots.
• The germ theory
• 1861 Louis Pasteur's
• famous experiments with
• swan-necked flasks finally
• proved that microorganisms
• do not arise by spontaneous
• generation
• This led to Development
• of sterilization

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Historical Theories

• Kochs postulates
• 1890s Robert Koch sets guidelines for how to
  prove that a particular microbial agent is
  responsible for a particular disease. Koch's
  postulates state that
• The suspect microorganism must be routinely
  isolated from patients with a particular illness
  
• The microorganism must be grown in pure culture
  in vitro
• When the pure culture is inoculated into a new
  host, it must cause the same illness
• The same microorganisms must be reisolated from
  new host.

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