MICROBIOLOGY Class 2

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MICROBIOLOGY Class 2

• To love what you do and feel that it matters
  how could anything be more fun? Katherine Graham

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Categories of Disease from Memmlers Chapter 5

• Infection
• Degenerative diseases
• Nutritional diseases
• Metabolic disorders
• Immune disorders
• Neoplasms
• Psychiatric disorders

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Complementary and Alternative Medicine (CAM)

• Naturopathy
• Chiropractic
• Acupuncture
• Biofeedback
• Exercise, massage, yoga, meditation, etc.
• NIH National Center for Complementary and
  Alternative Medicine (NCCAM)

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Predisposing Causes of Disease

• Age
• Gender
• Heredity
• Living conditions
• Emotional disturbance
• Physical and chemical damage
• Occupational diseases
• Preexisting illness

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Types of Illnesses

• Acute illness sudden onset and lasts for a short
  time
• Chronic illness comes on slowly and lasts a long
  time
• Terminal illness there is no potential for cure

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Survival of Microorganisms

• Spores
• Temporarily inactive microbial life form can
  resist heat and destructive chemicals and survive
  without moisture reactivate and reproduce when
  conditions are favorable
• Antibiotic-resistant bacterial strains
• No longer respond to drugs that once were
  effective against them

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Chain of Infection

• An infectious agent
• A reservoir for growth and reproduction
• An exit route from the reservoir
• A mode of transmission
• A port of entry
• A susceptible host

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Chain of Infection (contd)
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Medical Asepsis

• Confines or reduces the numbers of microorganisms
  
• Involves measures that interfere with the chain
  of infection in various ways
• Examples
• Performing hand hygiene
• Wearing hospital garments

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Principles of Medical Asepsis

• Microorganisms exist everywhere except on
  sterilized equipment
• Frequent handwashing and maintaining intact skin
  reduces transmission of microorganisms
• Blood, body fluids, cells, and tissues are major
  reservoirs of microorganisms
• Personal protective equipments serve as barriers
  to microbial transmission

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Sterilization

• Consists of physical and chemical techniques that
  destroy all microorganisms including spores
• Physical sterilization radiation, boiling water,
  free-flowing steam, dry heat, steam under
  pressure
• Chemical sterilization peracetic acid, ethylene
  oxide gas

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Principles of Surgical Asepsis

• Once equipment and areas are free of
  microorganisms, they remain in that state if
  contamination is prevented
• Sterility preserved touching one sterile item
  with another that is sterile
• Once a sterile item touches something that is not
  sterile, it is considered contaminated
• Any partially unwrapped sterile package is
  considered contaminated

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Principles of Surgical Asepsis (contd)

• Question the sterility of an item considered
  unsterile
• Longer the time since sterilization, the more
  likely that the item is no longer sterile
• Commercially packaged sterile item is not
  considered sterile past its recommended
  expiration date
• Opened sterile item or area, left unattended, is
  considered contaminated

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Principles of Surgical Asepsis (contd)

• Once a sterile item is opened or uncovered, it
  becomes contaminated
• The outer 1-inch margin of a sterile area is
  considered a zone of contamination
• A wet sterile wrapper wicks microorganisms from
  its supporting surface, causing contamination

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Principles of Surgical Asepsis (contd)

• Coughing, sneezing, or excessive talking over a
  sterile field causes contamination
• Reaching across an area that contains sterile
  equipment may cause contamination
• Sterile items located or lowered below waist
  level are considered contaminated

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General Gerontologic Considerations

• Older clients more susceptible to infections
• Maintain intact skin, proper aseptic techniques,
  perineal hygiene, thorough handwashing
  indwelling catheters should be avoided
• Bladder training, annual immunizations
• Ill health care workers should take sick leave
  rather than expose susceptible clients to
  infectious organisms

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Modes of Transmission

• From infected human, insect, or animal host to
  another susceptible host
• Through direct or indirect contact

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Portals of Entry and Exit

• Skin that is open
• Respiratory tract
• Digestive system
• Urinary and reproductive systems

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Microbiology The Study of Microorganisms

• Bacteria (bacteriology)
• Viruses (virology)
• Fungi (mycology)
• Protozoa (protozoology)
• Algae (algology)

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Naming Bacteria

• Genus name Capitalized and italic
• species name lowercase and italic
• EXAMPLE Escherichia coli or E. coli

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Bacteria

• Single-celled organisms
• Lack a true nucleus
• Found everywhere
• Anaerobic
• Aerobic
• Facultative anaerobes

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Shape and Arrangement of Bacteria

• Cocci
• Round
• Bacilli
• Short, slender rods
• Vibrios
• Short rods with a slight curvature
• Spirilla
• Long wavelike cells resembling a corkscrew
• Spirochetes
• Long wavelike cells capable of waving and
  twisting motions

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Viruses

• Extremely small microorganisms
• Composed of a core of nucleic acid (DNA or RNA)
  surrounded by a coat of proteins
• Grow only within living cells

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• Virus size comparison.

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Infectious Agents Smaller than Viruses

• Prions
• Composed solely of protein
• Viroids
• Composed solely of RNA, no protein coat

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Fungi

• Large group of simple plantlike organisms, few
  are pathogenic
• Yeasts
• Single-celled forms of fungi
• Molds
• Fuzzy, filamentous forms of fungi

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Protozoa

• Animal-like, single-celled microbes found all
  over the world
• Amebas
• Ciliates
• Flagellates
• Sporozoa

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• Some parasitic protozoa.
• Why are the parasites in E described as
  intracellular?
• What is the role of the vectors shown in C and
  E?

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Parasitic Worms

• Parasites with human hosts, also called helminths
• Helminthology
• The study of parasitic worms.

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Roundworms

• Ascaris
• Pinworms
• Hookworms
• Trichina (trichinosis)
• Filaria worm (filariasis, elephantiasis)

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Microbes and Public Health

• Sewage and garbage disposal
• Water purification
• Prevention of food contamination
• Milk pasteurization

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Microbial Control Needs

• Increase in world population
• Disruption of animal habitats
• Increased travel (SARS)
• Opportunistic infections
• Changes in food handling

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Aseptic Methods

• Sterilization
• Bacteriocidal
• Disinfection
• Antisepsis
• Bacteriostasis - Inhibit growth of bacteria
• Does NOT KILL all bacteria but suppresses the
  growth so the body has an easier time fighting
  off those present -

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IDEAL QUALITIES OF AN ANTIMICROBIAL AGENT

• Kill or inhibit growth of pathogens
• Cause no harm to the host
• Cause no allergic reactions in a host
• Be stable when stored in a liquid or solid form
• Remain in specific tissues in the body long
  enough to be effective
• Kill the pathogens before they mutate and become
  resistant to it

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HOW IT WORKS

• Must be able to travel to site of pathogen
  without harming host
• Target a metabolic process or structure that is
  not present as the host
• 5 common mechanisms of action
• Inhibition of cell wall synthesis
• Damage to cell membranes
• Inhibit either DNA or RNA synthesis or both
• Inhibit protein synthesis
• Inhibit enzyme activity

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BACTERIOSTATIC

• Inhibit growth of bacteria
• Does not KILL all bacteria but suppresses the
  growth so the body has an easier time fighting
  off those present
• BACTERIOCIDAL
• Kills the bacteria

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Infection Control Techniques

• Universal precautions
• Handwashing
• OSHA

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Laboratory Identification of Pathogens

• Obtain and label specimens from patients
• Grow out bacterial cells
• Isolate individual organisms
• Multiply to form colonies
• Stain cells so they can be seen (Gram Stain)
• Perform tests to identify organisms

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Gram Staining

• 1. Obtain the sample to be assessed.
• 2. Plate it on a microscope slide.
• 3. Stain it with water soluble crystal violet
  dye.
• 4. Acetone or ethel alcohol rinse dehydrates the
  peptidoglycan layer of the cell membrane. Gram
  Positive sample retains the violet stain.

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Gram staining contd

• 5. A counter stain (saffranin) is applied to the
  rinsed cell. The color will be red. This is a
  gram negative.
• After a quick water rinse, the staining is
  finished. Gram positive cells retain the violet
  stain and gram negative are red.
• TB accepts neither water soluble stain it must
  be checked with an acid-fast stain

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Other Methods of Identification

• Growth characteristics in liquid and solid media
• Oxygen requirements
• Ability of bacteria to utilize various
  carbohydrates
• Reaction to various chemicals
• Serologic (immunologic) tests

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Susceptibility

• Now that the culture has been identified, we need
  to know what antibiotic will kill it.
• The growth of the culture will have different
  antibiotics applied to determine which will kill
  the bacteria.
• If the antibiotic does not kill the bacteria, the
  bacteria is called resistant.
• Killed susceptible to the antibiotic

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Questions?