Micropara

• Microbiology is the study of microorganisms
• Key figures in the history of microbiology


  • Robert Hooke
  • Anton van Leeuwenhoek
  • Louis Pasteur
  • Ignus Semmelweis
  • Edward Jenner
  • Robert Koch
  • Julius Petri
  • Frae Hesse
  • John Tyndall
• Robert Hooke


  Discovered that all living things are made up of cells
• Anton van Leeuwenhoek


  • Father of Microscopy (discovered the first single-lens microscope)
  • Father of Microbiology (first to observe microorganisms - "animalcule")
  • Father of Protozoology (discovered Giardia lamblia in his own stool)
• Louis Pasteur


  • Father of Immunology
  • Discovered that microorganisms can exist in the absence of oxygen
  • Germ Theory of Disease
• Ignus Semmelweis


  Father of Hand hygiene/hand washing
• Edward Jenner


  Coined the term "vaccine" - for smallpox
• Robert Koch


  Koch's postulate
• Julius Petri


  Petri dish
• General characteristics of bacteria


  • Prokaryotic
  • Has both DNA and RNA
  • Chromosomal DNA
  • Non-Chromosomal DNA
  • Measured in um
  • Width: 0.25 - 1 um
  • Length: 1 - 3 um
  • Smallest Bacteria: Mycoplasma spp.
  • Largest PATHOGENIC Bacteria: Bacillus anthracis
  • Largest Bacteria: Thiomargarita magnifica

  
• Cell wall


  • Also known as Peptidoglycan Layer/Murein Layer/Mucopeptide
  • Protective layer
  • Maintains cell shape
  • Structure: NAG: N-acetylglucosamine, NAM: N-acetylmuramic acid
  • Primary basis of bacterial identification
• Gram staining


  • All cocci are gram positive, except (NVM): Neisseria, Veillonella, Moraxella/Branhamella
  • All bacilli are gram negative, except: Mycobacteria, Nocardia (mycolic acid), Mycoplasma, Ureaplasma (gram ghost), Corynebacterium, Clostridium, Bacillus, Lactobacillus, Listeria, Erysipelothrix, Actinomyces
  • All spirochetes are reported as gram negative
  • Yeasts are gram positive
• Bacterial shapes


  • Cocci (round)
  • Bacilli (rod)
  • Coccobacilli (ovoid)
  • Spirochetes (spirals)
  • Pleomorphic (no definite shape)

  
• Bacterial arrangements


  • Diplo (in pairs)
  • Tetrads (arranged in 4)
  • Sarcina (arranged in 8)
  • Staphylococci (in clusters)
  • Streptococci (in chain)

  
• Plasma membrane


  • Site of energy synthesis
  • Osmotic or permeability barrier
  • Regulate transport of nutrients in and out of the cell
  • Lacks sterols except for Mycoplasma spp.
  • With Mesosomes - invagination / cleavage / cell division
• Distinct areas of the cytoplasm


  • Inner nucleoid region (chromosomal DNA, circular in shape, reproduction: asexual / binary fission)
  • Amorphous matrix (ribosomes - site of protein synthesis, inclusion bodies - food reserves, plasmids - carries antibiotic-resistance gene)
• Extracellular structures


  • Capsule (antiphagocytic, antigenic determinant)
  • Slime layer (anti-phagocytic)
  • Pili (common/somatic/ordinary pili - bacterial adherence, sex/fertility/F pili - gene transfer)
  • Endospores (highly resistant structure, formed during stationary phase)
  • Flagella (whip-like structure for locomotion, made up of protein called flagellin, associated with H antigen)
• Bacterial growth requirements - gas


  • Obligate aerobes (requires oxygen)
  • Obligate anaerobes (does not require oxygen)
  • Facultative anaerobes (can live with or without oxygen)
  • Aerotolerant anaerobes (does not usually require oxygen but may tolerate limited exposure to oxygen)
  • Microaerophilic (prefers small concentration of oxygen)
  • Capnophilic (requires carbon dioxide for growth)
• Bacterial growth requirements - pH


  • Acidophile (requires acidic pH, examples: yeasts, Lactobacillus spp., vagina)
  • Neutrophile/Neutralophile (requires alkaline pH, most pathogenic bacteria)
  • Basophile/Alkalophile (requires basic pH, example: Vibrio cholerae)
• Bacterial growth requirements - temperature


  • Mesophilic (20 to 45C, most pathogenic bacteria)
  • Psychrophilic (-5 to 15C, example: Listeria monocytogenes)
  • Thermophilic (50 to 60C, example: Thermus aquaticus)
• Other bacterial growth requirements


  • Halophilic (requires high salt concentration, examples: Staphylococcus aureus, Vibrio spp., Enterococcus spp.)
  • Osmophiles (requires high osmotic pressure)
  • Humidophilic (requires moisture, most bacteria)
• Methods of sterilization - heat


  • Dry heat sterilization (direct flame, dry/hot air oven, incineration, autoclave)
  • Moist heat sterilization (tyndallization, inspissation)
• Other methods of sterilization


  • Ionizing radiation
  • Filtration
  • Peracetic acid/glutaraldehyde
  • Ethylene oxide
  • Boiling
  • Pasteurization
  • Non-ionizing radiation
  • Alcohol
  • Bleach
  • Iodine
  • Quartz (quaternary ammonium compounds)
• Antibody


  Proteins produced in response to an infection, specific, only produced in the presence of the specific antigen, produced by lymphocytes
• Antigen


  Any substance that can initiate the production of antibody
• Components of the immune system


  • Natural immunity (ability to resist infection by means of normal bodily function, no prior exposure required, response does not change with subsequent exposure, lacks memory and specificity)
  • Adaptive/Acquired immunity (specific for each individual pathogen, has memory and specificity, results in an increased response upon repeated exposure)
• Natural immunity - phagocytes


  • Neutrophils
  • Basophils
  • Eosinophils
  • Macrophages
  • Steps: chemotaxis, adherence, ingestion, digestion, excretion
• Acquired immunity


  • Naturally acquired (active immunity - after exposure to infection, passive immunity - antibodies acquired from mother)
  • Artificially acquired (active immunity - vaccine containing attenuated antigen, passive immunity - vaccine containing antibody)
• Factors affecting immune response

  • Class of antibodies
• Individual pathogen


  • Has memory and specificity
  • Results in an increased response upon repeated exposure
• NATURAL IMMUNITY


  • PHAGOCYTES
• Phagocytes


  • Cell eating
  • Neutrophils, Basophils, Eosinophils, Macrophages
• Phagocytosis


  1. Chemotaxis - chemical attraction to site

  2. Adherence - sticks to bacteria

  3. Ingestion - engulf bacteria

  4. Digestion - destroy bacteria

  5. Excretion
• ADAPTIVE/ACQUIRED IMMUNITY


  • Mediated by antibodies
• Types of Acquired Immunity


  • Naturally Acquired
  • Artificially Acquired
• Naturally Acquired Immunity


  • Active Immunity - after exposure to infection
  • Passive Immunity - antibodies acquired by infant from mother
• Artificially Acquired Immunity


  • Active Immunity - vaccine containing attenuated antigen
  • Passive Immunity - vaccine containing antibody
• FACTORS AFFECTING IMMUNE RESPONSE

  • CLASS OF ANTIBODIES
• IgG


  • Antibody that appears after re-exposure to an infection
  • Only immunoglobulin that can cross the placenta, most abundant
• IgA


  Antibody present in colostrum