Bacteria Project

Disease or Not: Introduction, Two Theories, Experiments on Germ theory, Experiments to Application Identification: Compare Microbes, Different from animals, Classification (based on properties) Taxonomical Position: How the bacteria placed in our life forms? Infection: Infection Route,Temperature, Air, Food, Insects, Contact-Poor-Hygiene. Defense: First-Line, Specific:(Phagocytic-cellular-humoral) immunity Physical & Chemical Controls Sterilization & Pasteurization Chemotherapy: Sulphonamides,Antibiotics: Action-Site, Aminoglycoside-Macrolides, peptide_bond Resistance: To antibioitc, Plasmid Mediated transfer

Some of the characteristics of bacteria that are employed in their classification and identification are:

• nature: Obligate or Faccultative
• morphology - cell shape and size
• staining reactions - especially gram staining reaction ( Open as New Page)
• metabolism - biochemical reactions
• growth characteristics including colony size, shape, and color
• environmental requirements - eg. oxygen tolerance, temperature tolerance, etc.
• serologic reactions - antigen-antibody reactions
• phage typing - using bacteriophages to identify bacterial strains
• DNA hybridization - to determine closeness of relationship between various bacteria
• base sequence of nucleic acids
• protein types - determined by polyacrylamide gel electrophoresis [ PAGE ]
• lipid types
• other characteristics

 

Obligate Intracellular: Must be intracellular to grow further.
Diseases Caused by Rickettsiaceae

• Human Disease - multiplication in endothelium of small blood vessels produces skin rash, fever, sever headache, malaise, prostration, spleen/liver enlargement; transmitted by ticks, lice , mites, and fleas (exception is Q-fever, Coxiella burnetti which is by direct transmission in man; by aerosol infection or by feces of tick vector in animals.
  • . Typhus Group ("typhus" - derived from Greek for "smoky" or "hazy" - mental state - Typhus Fever)
    •  Epidemic-louse borne (Rickettsia prowazekii; Brill-Zinsser disease)
      HUMAN>>>>LOUSE >>>>HUMAN
      
      Brill-Zinsser disease apparently a relapse years after symptomatic recovery from primary attack of epidemic typhus
    •  Endemic-murine flea borne (R. typhi or mooseri)
  • . Spotted Fever Group - Rocky Mountain Spotted Fever - Tick R. rickettsii - clinically resembles typhus - can also infect dogs (fever, anorexia, vomiting, diarrhea, and depression can occur within 2 to 3 days after tick attachment.
    
     

Morphology: Regular or Spiral

Staining

 

Bacteria can also be classified based ontheir tolerance to free oxygen in the environment:

• strict anaerobes - would die in the presence of free oxygen.
• facultative anaerobes - can live with or without oxygen.
• strict aerobes - must have abundant free oxygen.
• microaerophiles - as name suggests, require small amounts of oxygen, but  large amount oxygen will kill these bacteria.
• aerotolerants - do not use oxygen, and are tolerant to oxygen.

Very Often bacteria will produce some enzyme to defy the various toxic forms of oxygen:

• superoxide dismutase - converts the toxic superoxide free radical (O2^-.) to hydrogen peroxide (H2O2) and water
• peroxidase - converts the toxic peroxide ion (O2^-2 ) to water
• catalase - converts the peroxide ion to O2 and water