Download MICROBIOLOGY Class 2

MICROBIOLOGY Class 2
“To love what you do and feel that it
matters – how could anything be
more fun?” Katherine Graham
Categories of Disease from Memmler’s
Chapter 5
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Infection
Degenerative diseases
Nutritional diseases
Metabolic disorders
Immune disorders
Neoplasms
Psychiatric disorders
Complementary and Alternative
Medicine (CAM)
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Naturopathy
Chiropractic
Acupuncture
Biofeedback
Exercise, massage, yoga,
meditation, etc.
NIH: National Center for
Complementary and Alternative
Medicine (NCCAM)
Predisposing Causes of Disease
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Age
Gender
Heredity
Living conditions
Emotional disturbance
Physical and chemical damage
“Occupational” diseases
Preexisting illness
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
Survival of Microorganisms
 Spores
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Temporarily inactive microbial life
form; can resist heat and destructive
chemicals and survive without
moisture; reactivate and reproduce
when conditions are favorable
 Antibiotic-resistant
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bacterial strains
No longer respond to drugs that once
were effective against them
Chain of Infection
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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
Chain of Infection (cont’d)
Medical Asepsis
 Confines
or reduces the numbers
of microorganisms
 Involves
measures that interfere
with the chain of infection in
various ways
 Examples:
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Performing hand hygiene
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Wearing hospital garments
Principles of Medical Asepsis
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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
Sterilization
 Consists
of physical and chemical
techniques that destroy all
microorganisms including spores
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Physical sterilization: radiation, boiling
water, free-flowing steam, dry heat,
steam under pressure
Chemical sterilization: peracetic acid,
ethylene oxide gas
Principles of Surgical Asepsis
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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
Principles of Surgical Asepsis
(cont’d)
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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
Principles of Surgical Asepsis
(cont’d)
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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
Principles of Surgical Asepsis
(cont’d)
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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
General Gerontologic
Considerations
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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
Modes of Transmission
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From infected human, insect, or
animal host to another susceptible
host
Through direct or indirect contact
Portals of Entry and Exit
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Skin that is open
Respiratory tract
Digestive system
Urinary and reproductive systems
Microbiology –
The Study of Microorganisms
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Bacteria (bacteriology)
Viruses (virology)
Fungi (mycology)
Protozoa (protozoology)
Algae (algology)
Naming Bacteria
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Genus name: Capitalized and italic
species name: lowercase and italic
EXAMPLE: Escherichia coli or E. coli
Bacteria
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Single-celled organisms
Lack a true nucleus
Found everywhere
Anaerobic
Aerobic
Facultative anaerobes
Shape and Arrangement of
Bacteria
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Cocci
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Bacilli
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Short rods with a slight curvature
Spirilla
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Short, slender rods
Vibrios
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Round
Long wavelike cells resembling a corkscrew
Spirochetes
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Long wavelike cells capable of waving and twisting motions
Viruses
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Extremely small microorganisms
Composed of a core of nucleic acid
(DNA or RNA) surrounded by a coat
of proteins
Grow only within living cells
Virus size comparison.
Infectious Agents Smaller than
Viruses
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Prions
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Composed solely of protein
Viroids
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Composed solely of RNA, no protein
coat
Fungi
Large group of simple plantlike
organisms, few are pathogenic
Yeasts
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Single-celled forms of fungi
Molds
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Fuzzy, filamentous forms of fungi
Protozoa
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Animal-like, single-celled microbes
found all over the world
Amebas
Ciliates
Flagellates
Sporozoa
Some
parasitic
protozoa.
• Why are the
parasites in E
described as
intracellular?
• What is the
role of the
vectors shown
in C and E?
Parasitic Worms
Parasites with human hosts, also
called helminths
 Helminthology
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The study of parasitic worms.
Roundworms
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Ascaris
Pinworms
Hookworms
Trichina (trichinosis)
Filaria worm (filariasis,
elephantiasis)
Microbes and Public Health
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Sewage and garbage disposal
Water purification
Prevention of food contamination
Milk pasteurization
Microbial Control Needs
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Increase in world population
Disruption of animal habitats
Increased travel (SARS)
Opportunistic infections
Changes in food handling
Aseptic Methods
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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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 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
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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 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
Infection Control Techniques
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Universal precautions
Handwashing
OSHA
Laboratory Identification of
Pathogens
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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
Gram Staining
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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.
Gram staining cont’d
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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
Other Methods of Identification
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Growth characteristics in liquid and
solid media
Oxygen requirements
Ability of bacteria to utilize various
carbohydrates
Reaction to various chemicals
Serologic (immunologic) tests
Susceptibility
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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
Questions?