Download ST220_Microbiology_BB

ST220
Concorde Career College
MICROBIOLOGY
Microbiology
Objectives
 Define the term microbiology.
 Provide a timeline of events leading up to the current
understanding of microbiology.
 List and identify the parts of a microscope and
understand its use in a laboratory setting.
Microbiology
Microbiology – Study of microorganisms
Microorganisms – Microscopic organism
(plant or animal)
Microscopic – Minute; visible only with the
aid of a microscope
Microbiology
Microscope
 An optical instrument for making an enlarged
image of an object too small to be seen by
the naked eye
 Consists of a lens, or a combination of lenses
 Often provides light enhancement
 May be monocular or binocular
Microbiology
Microscope
Original van Leeuwenhoek
microscope
Microbiology
Microscope
Operating microscope used
for neurosurgical
procedures
Microbiology
Microbiology Timeline
 Robert Hooke
 1635-1703
 Cell theory – Proposed the idea that all living
things are composed of cells after viewing slices of
cork through a microscope in the year 1665.
Note: Hooke coined the term cell which is from
the Latin word cella meaning "storeroom" or
"small container"
Robert Hooke
Microbiology
Microbiology Timeline
 Anton van Leeuwenhoek
 1632-1723
 First to observe bacteria with a microscope
 Made the first accurate drawings of bacteria and
protozoa
Anton van Leeuwenhoek
Microbiology
Microbiology Timeline
 Francesco Redi
 1626-1697
 Disproved the theory of abiogenesis or
spontaneous generation (it was thought that new
living cells could spontaneously arise from
nonliving material)
Francesco Redi
Microbiology
Microbiology Timeline
 Louis Pasteur
 1822-1895
 Proved the theory of biogenesis (new living cells can only arise
from preexisting living cells)
 Developed the “germ theory of disease”
 Promoted hand washing and a clean environment to reduce the
spread of disease in hospitals
 Developed several vaccines (anthrax, cholera, rabies)
 Developed "pasteurization," a method of destroying harmful
microbes in perishable food products using heat, without
destroying the food
Louis Pasteur
Microbiology
Microbiology Timeline
 Edward Jenner
 1749-1823
 Developed smallpox vaccination
 Father of Immunology
Edward Jenner
Microbiology
Microbiology Timeline
 Ignaz Semmelweis
 1818-1865
 Correlated frequent handwashing in the obstetrics
ward with lower rates of infection (puerperal
fever)
Note: the term puerpera refers to a woman who
has just given birth
Ignaz Semmelweis
Microbiology
Microbiology Timeline
 Joseph Lister
 1827-1912
 Recognized the significance of Pasteur’s findings and established
the first principles of asepsis and the practice of sterile technique
 Used carbolic acid (phenol) to treat surgical wounds and dressings
 Wore clean gown and gloves for each surgical procedure
 Boiled instruments between surgical procedures
Joseph Lister
Microbiology
Microbiology Timeline
 Robert Koch
 1843-1910
 Proved Pasteur’s germ theory
 Developed pure culture techniques still used today
Robert Koch
Microbiology
Microbiology Timeline
 Hans Gram
 1853-1938
 Developed staining methods (Gram’s stain)
utilized to identify various species of bacteria
Hans Gram
Microbiology
Organism Identification
 Staining – Involves application of a colored
dye (called a stain) to an organism to enhance
visualization and allow identification of a
specific organism.
 Gram Stain
 Acid-fast Stain
Microbiology
Organism Identification
 Gram Stain
 Organism is stained with blue/purple dye
 Weak iodine solution is added to promote
colorfastness
 Slide is washed with alcohol
 If blue/purple dye remains the organism is Gram
positive
 If blue/purple dye is removed the organism is
Gram negative and is then stained with pink/red
dye to enhance visibility
Positive or Negative?
Anthrax rods in CSF
Pseudomonas aeruginosa
Microbiology
Organism Identification
 Acid-fast Stain
 Organism is stained with red dye
 Smear is treated with acid
 Most organisms quickly loose the red color when
treated with acid
 Those that remain colored (e.g., Mycobacterium
tuberculosis) are called acid-fast
Acid-fast Stain
Mycobacteria
paratuberculosis in
bovine ileum
Microbiology
Organism Identification




Culturing – Growing cells in enriched media
Fermentation – Action of organism on sugars
Observation – Reaction to test chemicals
Inoculation – Injection and observation of test
animals
 Immunology – Antigen-antibody reaction
Culture
Microbiology
Microscope Types
 Compound Light Microscope
 Dark Field Microscope
 Phase Contrast Microscope
 Fluorescence Microscope
 Electron Microscope
Microbiology
Compound Light Microscope
 Also called “bright field”
 Two lens system
 First lens located in the
objective near the specimen
 Second lens in the eyepiece
 Light source
Microbiology
Dark Field Microscope
 Similar to bright field
microscope – contains a light
condenser with an opaque disc
that blocks direct light;
allowing peripheral light to
enter
 Utilized when microbes cannot
be stained
 Effective for viewing motility
when microbes are suspended
in liquid (wet mount)
Dark Field
Microbiology
Phase Contrast Microscope
 Light condenser contains
ring shaped diaphragm
that allows light of various
brightness (phases) to
pass through –
highlighting the internal
structures of the cell
Phase Contrast Samples
Microbiology
Fluorescence Microscope
 Utilized ultraviolet light to
visualize fluorescent
microbes or those stained
with fluorochromatic dye
 Especially useful in
identification of rabies
and syphilis
Fluorescence Microscope
Microbiology
Electron Microscope
 Utilizes a beam of electrons in
place of light which improves
resolution
 Utilizes an electromagnetic
lens in place of a glass lens
which focuses the electron
beam onto the specimen
 Scanning electron microscope
is pictured
Electron Microscope
Pollen
Microbiology
Microscope Components
 Eyepiece
 Body tube
 Arm
 Revolving nosepiece
 Objectives
 Stage with clips
 Focus adjustment knobs
 Diaphragm
 Light source
 Base
Microbiology
Microbiology
Microscope – Care and Handling
 When carrying the microscope hold the arm with one
hand and support the base with the other
 Never touch the lenses
 Use only lens paper to clean the lenses
 When finished with the microscope




Rotate the nosepiece to the low power objective
Lower the nosepiece down to the stage
Secure the cord
Replace the dust cover
Microbiology
Objectives
 List and identify the components of a cell and
describe the function of each.
 List and define fluid movement concepts.
 List the major classifications of organisms.
Microbiology
 Cell Theory
 Anton von Leeuwenhoek
 Observed pond water under microscope
 Noted organisms that he called “animalcules”
 Principles of modern cell theory
 Cells are the smallest complete living things (basic unit of
organization of all organisms)
 All organisms are composed of one or more cells in which all life
processes occur
 Cells arise only from preexisting cells through the process of cell
division.
 All existing cells are descendants of the first cells formed in history.
Microbiology
 Cell Structure












Cell membrane
Cytoplasm
Nucleus
Nuclear membrane
Nucleoplasm
Chromatin
Nucleolus
Mitochondria
Lysosomes
ER – endoplasmic reticulum (rough, smooth)
Golgi apparatus
Ribosomes
Microbiology
 Cell Membrane
 Also called the plasma membrane or




plasmalemma
Consists of a double phospholipid layer containing
proteins
Phospholipids allow free passage of water
molecules through the cell membrane via osmosis
(hydrophilic/hydrophobic)
Some proteins allow passage of molecules and
ions via transport channels or by active transport
Other proteins act as receptor sites and identity
markers
Phospholipid Bilayer
Microbiology
 Cytoplasm
 Main constituent is water that contains chemical
compounds (e.g., mineral salts) in solution and
organic compounds in colloidal suspension
 Also contains storage granules, fat droplets, and
vacuoles (area within the cytoplasm surrounded
by a membrane filled with a watery mixture of
nutrients or waste products
Cytoplasm
Microbiology
 Nucleus
 Control center of the cell
 Surrounded by a
membrane
 Contains genetic
material
Microbiology
 Nuclear Membrane
 Porous double nuclear membrane that allows
passage of materials (e.g., messenger RNA) to the
cytoplasm
 Inner layer surrounds the nucleoplasm
 Outer layer connects with the ER
Nuclear Membrane
Microbiology
 Nucleoplasm
 Fluid portion of the
nucleus
Microbiology
 Chromatin
 Genetic material contained
within the nucleoplasm
 Darkly stained threads of
nucleic acids
 Duplicates, shortens, and
thickens during cell division
and becomes visible as
chromosomes
Microbiology
 Nucleolus
 Spherical particle within
the nucleoplasm
 Produces ribosomes
Microbiology
 Mitochondria
 Powerhouse of the cell
 Composed of two membranes
 Outer membrane forms capsular shape
 Inner membrane folds into itself to increase surface
area (folds are called cristae)
 Aerobic phase of cellular respiration occurs in the
mitochondria
Mitochondrion
Microbiology

Lysosomes


Small structures in the cytoplasm containing
powerful digestive enzymes and surrounded by a
membrane
Perform three important functions
1. Work with food vacuoles to digest stored food
2. Maintain and repair organelles (building blocks of
protoplasmic structures)
3. Destruction of old or weakened cells
Lysosomes
Microbiology
 Endoplasmic Reticulum (rough, smooth)
 Complex system of membranes that make up
channels called cisternae
 Connects the outer nuclear membrane with the
cell membrane
 All cells have rough ER
 Rough ER has attached ribosomes that synthesize
protein
 Some cells have smooth ER
 Smooth ER transports fat or synthesizes sex
hormones
Endoplasmic Reticulum
Microbiology
 Golgi Apparatus
 Collection of flat saclike cisternae
 Store compounds secreted by the cell
 Aid in synthesis of necessary substances (e.g.,
carbohydrates)
Golgi Apparatus
Microbiology
 Ribosomes
 Small granules distributes throughout the
cytoplasm that are attached to the ER
 Site of protein synthesis
Ribosomes on Rough ER
Microbiology
 Fluid Movement Concepts
 Diffusion
 Osmosis
 Active Transport
 Filtration
Microbiology
Diffusion
 Movement of
molecules through a
medium from an area
of high concentration
to an area of low
concentration.
Microbiology
Osmosis
 Movement of a solvent (e.g., water) through
a semipermeable membrane from an area of
high concentration to an area of low
concentration
Osmosis
Microbiology
Active Transport
 Movement of substances (e.g., sugars, amino
acids, large proteins, fats) through the cell
wall from an area of lower concentration to
an area of higher concentration using energy
in the form of ATP (adenosine triphosphate)
Active Transport
Microbiology
Filtration
 Passage of a liquid or
gas through a
permeable membrane
to remove particulate
matter
Microbiology
Movement of Items Other Than Water
 Endocytosis
 Exocytosis
Microbiology
 Endocytosis
 Particles are taken into the cell (e.g., bacteria,
nutrients)
 Three types of endocytosis
 Phagocytosis
 Pinocytosis
 Receptor-mediated endocytosis
Microbiology
 Phagocytosis
 Movement of other
organisms or
fragments of organic
matter into the cell
Macrophage
Phagocytosis
Microbiology
 Pinocytosis
 Movement of fluids
(other than water)
into the cell
Pinocytosis
Microbiology
 Receptor-Mediated
Phagocytosis
 Receptors on the cell surface
detect specific molecules
and allow rapid movement
of the molecule into the cell
Microbiology
 Exocytosis
 Movement of particles
(e.g., hormones,
neurotransmitters,
digestive enzymes) out
of the cell
 Via secretory granules
originating in the Golgi
apparatus
Platelet Exocytosis
Microbiology
Major Classifications of Organisms (Nomenclature)







Kingdom (plantae, animalia, fungi, protists, monera)
Phylum
Class
Order
Family
Genus
Species
Classification
Microbiology
Specific Classes of Microorganisms







Algae
Protozoa
Fungi (yeasts, mushrooms, molds)
Bacteria
Rickettsiae
Viruses
Prions
Microbiology
Objectives
 Define the term algae, list its characteristics,
and explain its relationship to humans.
 Define the term protozoa, list its
characteristics, and explain its relationship to
humans.
Microbiology
 Algae (Definition and Characteristics)
 Protist Kingdom (simplest organisms)
 Eukaryotic (nucleus surrounded by a membrane)
 Photosynthetic (contains chlorophyl – manufactures
carbohydrates and oxygen by combining CO2 and H2O using
sunlight)
 Nonparasitic
 Lacks roots, stems, leaves, and flowers
 May be microscopic (unicellular) or massive (multicellular)
Algae
Microbiology
 Algae (Relationship to Humans)
 Ecological balance
 Indication of ecological imbalance
 Food source
 Blue-green algae – Cyanobacteria responsible for
epidemic diarrhea
Microbiology
 Protozoa (Definition and Characteristics)
 Protista Kingdom (simplest organisms)
 Unicellular – animal like microorganisms
 Saprophytes (lives on dead or decaying matter)
Microbiology
Ciliated Protozoa
Microbiology
Flagellated Protozoa
Microbiology
 Protozoa (Relationship to humans)
 Common protozoa infections
 Malaria (Plasmodium vivax, P. malariae)
 Gastroenteritis (Entamoeba histolytica, Giardia
lamblia)
 Leishmaniasis – inflammation of the skin or viscera
(Leishmania species)
 Sleeping sickness (Trypanosoma brucei gambiense)
 Vaginal infections (Trichomonas vaginalis)
Trypanosoma brucei
Microbiology
Malaria
(Plasmodium malariae)
Microbiology
 Protozoa
 Spread of infection (opportunistic – most
commonly affects immunosuppressed individuals)
 Fecal-oral contamination
 Ingestion of contaminated food or water
 Vector
 Mosquito
 Human sexual contact
Microbiology
Trichomonas vaginalis
Microbiology
Objective
 Define the term fungus (yeasts, mushrooms,
and molds), list the characteristics of each,
and explain the relationship of each to
humans.
 Define the term helminth, list its
characteristics, and explain its relationship to
humans.
Microbiology
 Fungi (Definition and Characteristics)
 Protist Kingdom
 Eukaryotic
 Chemoheterotrophic (uses chemicals as energy




source)
Requires an external carbon source
Lack chlorophyll
Saprophytic or parasitic
Reproduction occurs either by budding (sexual) or
spore formation (asexual)
Microbiology
 Fungi (Definition and Characteristics -
continued)
 Grow in irregular masses
 Devoid of roots, stems, and leaves
 May be unicellular or filamentous (threadlike in
structure)
 Includes yeasts, mushrooms, and molds
Mycology is the study of fungi
Mycoses are fungal diseases
Microbiology
Yeast (baking, brewing)
Saccharomyces cerevisiae
Microbiology
Yeast
(esophageal candida
albicans)
Microbiology
Mushroom
Microbiology
Mold
Microbiology
Onychomycosis
Microbiology
 Fungus (Relationship to humans)
Benefits
 Molds – decompose organic matter/produce
antibiotics
 Mushrooms – edible
 Yeasts – fermentation/leavened bread/normal
body flora
Microbiology
 Fungus (Relationship to humans)
Mycoses – Typically opportunistic in humans
 Immune deficiency
 Immunosuppression
 Corticosteroid use
 Chemotherapy
 Antibiotic therapy
 Comorbid condition (e.g., diabetes)
Microbiology
 Fungus (Relationship to humans)
Mycoses (examples)
 Aspergillosis – air conditioning contaminant that
commonly affects the respiratory tract
 Zygomycosis – contaminant found in soil and on
fruit and plants
 Candida (yeast) – normal mucosal flora
 Cryptococcus – enters through the respiratory
tract and can spread to other internal organs
including the nervous system (cryptococcal
meningitis)
Microbiology
 Helminths (Definition and Characteristics)
 Worms (includes eggs and larvae)
 Parasitic (referred to an infestation rather than
infection)
Microbiology
 Helminths (Relationship to humans)
 Roundworms
 Ascaris




Prevalent in larval form in Asia
Prevalent in egg form in the Southern US
Enter the digestive system via contaminated food
Infests lungs and intestines
Microbiology
Human Intestinal
Roundworm
(Ascaris Lumbricoides)
Microbiology
 Helminths (Relationship to humans)
 Roundworms
 Trichina




Encapsulated worms found in host’s muscle (e.g., pork)
Undercooked pork is ingested
Digestive juices dissolved by new host
Worms mature and infest new host’s muscle
Microbiology
Trichina
Microbiology
 Helminths (Relationship to humans)
 Roundworms
 Filariasis (caused by a small threadlike worm)




Common in tropical and subtropical areas
Transmitted by biting insects (e.g., flies, mosquitos)
May infest cardiovascular system (e.g., heartworm)
May infest lymphatic system (e.g., elephantiasis)
FILARIASIS
Microbiology
Elephantiasis
Microbiology
Heartworm
Microbiology
 Helminths (Relationship to humans)
 Pinworms




Common type Enterobius vermicularis (seat worm)
Especially prevalent in children
Initially ingested
Female exits anus to lay eggs, anal eggs cause
itching, eggs are reintroduced to the GI tract via the
fingers, re-infestation occurs
Microbiology
Enterobius vermicularis
Microbiology
 Helminths (Relationship to humans)
 Hookworms
 Small larvae live in soil
 Larvae penetrate intact skin of the bare foot
 Transported to the intestine by the blood
 Leech blood from the host’s intestinal mucosa
causing anemia
Microbiology
Hookworm
Microbiology
 Helminths (Relationship to humans)
 Flatworms
 Tapeworm
 Ingested in improperly cooked meat (e.g., beef,
pork, and fish)
 May grow to the length of the intestinal tract (up
to 50 feet)
Microbiology
Human Intestinal Flatworm
Tapeworm
(Taenia Pisiformis)
Tapeworm
Microbiology
 Helminths (Relationship to humans)
 Flatworms
 Flukes
 Leaf shaped flatworms
 Invade the blood, lungs, liver, and intestine
Microbiology
Fluke
Microbiology
Objectives
 Define the term bacteria, list its
characteristics, and explain its relationship to
humans.
Microbiology
Bacteria
 Unicellular, prokaryotic (lacks a true nucleus)
organisms that usually multiply by cell
division
 May be capable of producing spores
(resistant form that can tolerate adverse
conditions)
 Compose the largest group of pathogens
Microbiology
Bacteria
 May be:
 Aerobic
 Motile (flagella)
 Free-living
 Saprophytic
 Pathogenic
- Anaerobic
- Nonmotile
- Commensal
- Parasitic
- Beneficial
Microbiology
Bacterial Classifications
 Bacilli – rod shaped cells
 Straight
 Slender
 Cigar shaped with tapered ends
 Common bacillary diseases:
 Tetanus
 Diphtheria
 Tuberculosis
 Typhoid fever
Microbiology
Clostridium tetani
Microbiology
Tetanus
 Anaerobic, Gram positive rod
 Found in soil, dust, and manure
 Enters through a break in the
skin
 Affects the CNS causes tetany
 Symptoms appear 3-21 days
following exposure
 Usually fatal by asphyxiation
 Vaccine available
Microbiology
Other common clostridium diseases
 Botulism – Clostridium botulinum
 Food poisoning – Clostridium perfringens
 Antibiotic-associated colitis – Clostridium difficile
 Necrotizing enteritis – Clostridium perfringens
 Uterine and wound infections – Clostridium perfringens
and others
Microbiology
Corynebacterium diphtheriae
Microbiology
Diphtheria
 Acute bacterial disease
 Enters the respiratory tract
 Commonly affects the throat
(tonsils), nose, and skin/may
also affect the
pericardium/swollen lymph
nodes/produces a membrane
 Usually fatal by asphyxiation
 Symptoms appear 1-6 days
following exposure
 Vaccine available
Microbiology
Mycobacterium tuberculosis
Microbiology
Tuberculosis

Usually attacks the lungs, but
may affect any body tissue
 Diagnosed with skin test or chest
X-ray
 Enters the respiratory tract
 Respiratory symptoms include:
Cough that lasts longer
than 2 weeks
 Pain in the chest
 Coughing up blood or
sputum


No vaccine/treatment lengthy
Microbiology
Bacterial Classifications
 Cocci – spherical cells
 Round (characteristic arrangements)
 Diplococci – pairs
 Gonorrhea
 Meningitis
 Streptococci – chains
 Strep throat
 Staphylococci - clusters
Microbiology
Neisseria gonorrhoeae
Microbiology
 Gonorrhea
 Gram negative diplococci
 STD
 Purulent penile or cervical discharge
 Frequent painful urination
 Ectopic pregnancy
 Sterility
 Epididymitis
Microbiology
Gonorrhea
Glans penis
Microbiology
Gonorrhea
Vaginal
Microbiology
Gonorrhea
Transmitted to the
neonatal eye during
childbirth
Microbiology
Neisseria Meningitidis
Microbiology
Bacterial Meningitis
 Bacterial normal flora in




upper aerodigestive tract
High fever
Headache
Neck stiffness
Photosensitivity
Microbiology
Streptococcus pyogenes
Microbiology
Strep Throat
 Fever
 Pain
 Redness
 Swelling
Microbiology
Necrotizing Fascitis
Also caused by streptococcus
pyogenes
Microbiology
staphylococcus aureus
Microbiology
Staph Infection
Carpal tunnel release – 1
week postop
Patient complaining of
worsening throbbing pain
in the hand and pain with
any movement of the
fingers
Microbiology
Carpal tunnel filled with
purulent matter caused by
a s. aureus deep wound
infection
Microbiology
Infection spread into the forearm
through the flexor tendon
compartments as well as up
into the small finger flexor
tendon sheath. She was treated
with repeated radical
debridement, intravenous
antibiotics, and delayed wound
closure. Her infection was
cured, but she was left with
stiffness of the small finger.
Microbiology
Staphylococcus aureus
 Gram positive cocci
 Normal skin flora
 Opportunistic pathogen
 Major cause of SSI
Microbiology
Common minor infections caused by s. aureus
 Folliculitis
 Boils
 Sties
 Impetigo
 Superficial abscesses
Microbiology
Common severe infections caused by s. aureus
 Food poisoning
 TSS
 Pneumonia
 Osteomyelitis
 Lactation mastitis
 Endocarditis
 Bacteremia
 SSI
 Rheumatic and scarlet fevers
Microbiology
Bacterial Classifications
 Vibrio – comma shaped rods
 Spirilla – corkscrew shaped rods
 Spirochetes – corkscrew shaped rods capable
of waving and twisting motions
Microbiology
 Vibrio cholerae
 Cholera
 Found in drinking water
contaminated with feces
 Severe diarrhea
 Death can occur within
hours of onset of symptoms
Microbiology
Spirilla
Commonly found in fresh water
streams
Causes diarrhea – poses a danger
to wilderness campers
One cell can multiply to over a
million cells in less than three
hours (exponentially)
Microbiology
Spirochete
Treponema pallidum (syphilis)
Microbiology
Syphilis – Treponema
pallidum
 STD – Four stages
 Primary syphilis –
transmitted from primary
sore (chancre) of affected
individual to the mucous
membranes (vaginal, anal,
oral) of another
Microbiology
 Secondary syphilis
 Rash appears 3-6 weeks
after initial chancre (usually
on palms of hands or soles
of feet)
 Transmission may occur
from ANY physical contact
during this phase
Microbiology
 Latent syphilis
 Noncontagious stage
 Tertiary syphilis
 Can damage any organ
system
 Causes mental illness,
blindness, neurologic
disorders, heart disease, and
death
Microbiology
Objective
 Define the term rickettsia, list its
characteristics, and explain its relationship to
humans.
Microbiology
Rickettsia
 Distinct bacterial group
 Discovered by American pathologist Harold Taylor




Ricketts
Gram negative bacilli (rods) or cocci (spheres)
Obligate intracellular parasites
Pleomorphic (occur in more than one morphologic form –
able to mutate)
Common feature – spread by arthropod vectors
Microbiology
Rickettsia prowazekii
 Causes typhus
 Louse-borne
Microbiology
Rickettsia rickettsii
 Causes Rocky Mountain
Spotted Fever
 Spread by ticks, dogs,
rodents
Microbiology
Objective
 Define the term virus, list its characteristics,
and explain its relationship to humans.
Microbiology
Virus
 A virus is a small microorganism (smaller than
bacteria) that cannot replicate unless it is within
a living cell (obligate intracellular parasite).
 Most viruses are pathogenic with the exception
of bacteriocidal viruses (bacteriophages).
 Viruses are NOT affected by antibiotics.
 All viruses are capable of mutation.
Microbiology
Virus – Main components
 Capsid – Outer protein shell that encloses the genetic
material
 Core – Certain viruses also contain a protein layer
underneath the capsid that also surrounds the genetic
material
 Genetic material – DNA or RNA (“usually” not both)
 Envelope - Some viruses have an additional outer
covering called an “envelope” that may appear to have
spike-like projections
Virus Anatomy
Microbiology
Viruses can affect:
 Plants
 Animals
 Bacteria
All viruses have an affinity for a particular host.
For example a human cannot contract a plant
virus.
Microbiology
Classification – Viruses are classified by the
disease that they cause.
Examples:
Common cold
Polio
Chickenpox
Smallpox
Measles
Hepatitis
AIDS
Microbiology
Common Cold Virus
(rhinovirus)
Microbiology
Measles
http://www.mayoclinic.com/health/measles/DS00331
Microbiology
Poliomyelitis
http://www.who.int/topics/poliomyelitis/en/
Microbiology
Hepatitis B
(affected liver)
http://www.emedicinehealth.com/hepatitis_b/article_em.htm
Microbiology
Chickenpox
(varicella)
http://emedicine.medscape.com/article/969773-overview
Microbiology
Shingles
(Herpes Zoster)
https://health.google.com/health/ref/Shingles
Microbiology
HIV
(Human immunodeficiency
virus – causes AIDS)
http://www.cdc.gov/hiv/topics/basic/
HIV Attacking a White Blood
Cell
Microbiology
Smallpox Virus
(Variola Virus)
http://www.who.int/mediacentre/factsheets/smallpox/en/
Smallpox Victim
Smallpox Victim
Microbiology
Objective
 Define the term prion, list its characteristics,
and explain its relationship to humans.
Microbiology
Prion (pronounced “pree-on”)
 The word prion represents the term proteinaceous
infectious particle
 Prions were first identified in 1982 by Stanley Prusiner of
UCSF
 ALL known prion diseases are FATAL because the
immune system does not recognize proteins as foreign
and protection does not develop
Microbiology
Proteinaceous Particle
(Infectious)
Microbiology
Prion
 Simple protein
 Much smaller than a virus
 Unique because it lacks a
genome - (All other
known infectious agents
contain genetic material)
Microbiology
Prion
 Protein particles exist in two forms.
 The normal, an innocuous (harmless) protein called
PrPc can change its shape to a harmful, diseasecausing form called PrPSc
 The abnormal, conversion from PrPc to PrPSc then
proceeds via a chain reaction
 Several PrPSc proteins form long filamentous aggregates
that gradually damage neuronal tissue
PrPSc is VERY resistant to high
temperatures, UV-irradiation, and strong
degradative enzymes
Microbiology
Prion
 Prion diseases affect animals and humans
Microbiology
Sheep
Scrapie
First described in the 18th
century
http://www.aphis.usda.gov/animal_health/videos/scrapie-narrated.mpg
Microbiology
Cows
Bovine Spongiform
Encephalopathy – BSE
(Mad Cow Disease)
http://www.5min.com/Video/Risks-of-Mad-Cow-Disease-173033501
http://www.fda.gov/animalveterinary/guidancec
omplianceenforcement/complianceenforcement
/bovinespongiformencephalopathy/default.htm
Microbiology
Deer
Chronic Wasting Disease
(CWD)
http://www.cwd-info.org/index.php/fuseaction/about.main
Microbiology
Humans
Creutzfeldt-Jacob Disease
(CJD)
Gross Appearance
First reported in the 1920s
http://www.mayoclinic.com/health/creutzfeldt-jakob-disease/DS00531
Microbiology
Humans
Creutzfeldt-Jacob Disease
(CJD)
Cross-Section
Microbiology
Humans
Creutzfeldt-Jacob Disease (CJD)
Micro - Histology
Microbiology
Humans




Kuru
Appeared in New Guinea in the
early 1900s
Recently identified as a prion
disease
Ritual mortuary cannibalism
caused fatal epidemic
Disease irradicated when
cannibalism was terminated
Microbiology
How are prion diseases acquired? Theories include:
 Genetic transmission
 Spontaneous mutation of the proteinaceous particle
 Consumption of infected meat (including cannibalism)
 Transplantation/injection (e.g., dura mater, cornea,
growth hormone)
 Contact with contaminated surgical instrumentation
Microbiology
Recommended Practices
 Incinerate items used on known spongiform
encephalopathy patients
 Quarantine items until disease is ruled out
 Staff education
 Develop policies, procedures, and guidelines
for suspected cases
Microbiology
Modified Sterilization Protocol (when
incineration is NOT an option)
 Steam Sterilization (previously cleaned items)
 272º F for 18 minutes or 250º F for 1 hour
OR
 Soak
 1 hour in 5,000 ppm sodium hypochlorite (NaOH)
or 1 molar (M) sodium hydroxide THEN rinse,
clean, and steam sterilize as described above