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Flashcards in Microbiology Exam 2 Deck (97):
1

Exogenous

An infection in which the causative agent comes from outside the body

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Endogenous

An infection which is caused by microorganisms which are normally present within the body

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Acute

an infection of sudden onset and short duration (meningococcemia)

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Chronic

an infection of slow onset and long duration (Alzheimer's)

5

Communicable

An infection capable of being transmitted, either directly or indirectly, from host to host. Contagious means highly communicable

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Endemic

An infection that is constantly present to a greater or lesser degree in a community Ex: cold flu

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Epidemic

An infection which attacks a large number of people in a community in a short period of time

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Pandemic

Worldwide epidemic; an infection which becomes an epidemic in a number of countries at the same time ex: flu in 1919 killed 20 million

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Sporadic

An infection which occurs only occasionally (now and then) in a community (Legionnaire's disease; 4 corners region=Hantavirus)

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Primary

the initial (first) infection of a mixed infection

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Mixed

an infection due to two or more organisms ex: 2 or more infections occurring at the same time

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Secondary

the second and generally more complicating infection in a mixed infection

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Local

an infection in which the pathogenic organisms remain confined to a particular area (abscessed tooth)

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Focal

an infection confined to a particular area, but from which the bacteria spread to other parts of the body

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General

Infection throughout, spread generally over the body by the bloodstream or lymphatic system (septicemia/sepsis)

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Bacteremia

a condition in which bacteria are in the bloodstream but are not multiplying there

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Septicemia

Invasion of the bloodstream by pathogenic organisms with their subsequent multiplication therein. Common name is "blood poisoning" (sepsis)

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Toxemia

the presence of toxins (poisonous substances) in the blood

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Terminal

an infection which occurs during the course of a chronic disease and causes death

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Contamination

The presence of infectious material, without a reaction necessarily being produced. This term can also refer to inanimate objects (fomite)

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Infestation

The invasion of the body by macroscopic parasites; those able to be seen with the unaided eye (maggots)

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Virulence

the ability of a microorganism to produce disease. Attenuation implies a weakening or reduction in the virulence of a microorganism

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Zoonotic

Diseases caused by infectious agent that can be transmitted between (or are shared by) animals and humans (malaria; encephalitis)

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Nosocomial

A hospital-acquired infection; one obtained while in the hospital (staph)

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Pyemia

Literally, pus in the blood; a form of septicemia cause by cryogenic (pus-forming) bacteria

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Fulminating

A sudden, severe and overwhelming infection, such as spinal meningitis

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Generalized

infection throughout the body, having been spread by the bloodstream or lymphatic system

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Latent

A seemingly inactive infection; it is apparently held in check by the body's defense but may spread when the body resistance is reduced (cold sores, syphilis)

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Inapparent

an infection in which the clinical symptoms are not recognized or immediately detectable (TB)

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Typical mumps

an infection in which all the symptoms are easily recognized (rubella)

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Atypical

An infection in which all symptoms are not easily recognizable, meaning that it could be confused with another infection

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Pathogens

any microorganism that causes disease in man. A non-pathogen does not cause disease in man

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Types of Pathogens

Normal Flora
Opportunists
Strict (obligate) pathogens

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Normal Flora/ Indigenous flora

Microorganisms that live and grow in and on the human body. Most are non-pathogens

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Opportunists

Microorganisms that produce infection only under especially favorable conditions, that is, they await the right opportunity to cause infection. Pathogens contained in a person's normal flora are usually opportunists since they alone cannot penetrate unbroken skin

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Strict (obligate) pathogens

microorganisms that will cause an infection in man every time that a person is exposed to them. they are never a part of one's normal flora (streptococcus pyogenes)

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Bacterial typical reproduction is by?

binary fission (simple transverse division) an asexual means

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Binary Fission

a method of asexual reproduction involving halving of the nucleus and cytoplasm of the cell followed by the development of each half into a new individual

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asexual reproduction

has everything it needs to reproduce on its own

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Bacterial colony

a visible group of bacteria growing on a solid medium, presumably arising from a single microorganism (nutrient broth, blood agar)

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What are the conditions affecting bacterial growth?

1. Food requirements
2. Oxygen requirements
3. Moisture (water) requirements
4. pH
5. Temperature requirements
6. Effect of light on bacterial growth
7. Osmotic pressure

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Autotrophic bacteria

self nourishing bacteria; obtain there food from an organic matter, does not contain carbon

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Heterotrophic bacteria

other than self nourishing; organisms that must obtain their nourishment from complex organic matter; does contain carbon

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Strict (obligate) saprophytes

an organism that can only survive on dead or decaying organic matter

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Strict (obligate) parasite

an organism that is completely dependent on its living host for survival

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Strict (obligate) aerobe

a microbe that can only live in the presence of free oxygen (Humans)

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Strict (obligate) anaerobe

a microbe that can only survive in the absence of free oxygen (Clostridium/ gang-green)

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Microaerophilic

a microorganism that requires very little free oxygen (a level less that is required for humans)

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pH

percentage of Hydrogen ion in solution; slightly alkaline for most pathogens

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Facultative bacteria

organisms that can live in the presence or absense or oxygen

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Minimum temperature

lowest temperature at which any organism could live

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Maximum temperature

highest temperature at which any organism could live

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Optimum temperature

temperature at which any organism grows best at

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Psychrophiles (cryophiles)

organisms that grow best at cold temperatures below 20 degrees C

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Mesophiles

most pathogens organisms that prefer moderate temperature and develop best at temperatures between 20 and 40 degrees C

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Thermophiles

organisms that thrive best at high temperatures, above 40 degrees C

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Effect of light on bacterial growth

UV light is bactericidal

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Osmotic pressure

pressure that develops when two solutions of different concentrations are separated by a semi-permeable membrane

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Isotonic

this solution is important to study bacterial cells & red blood cells

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Hypertonic

excess solute (water leaves the cells cause shrinkage)

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Plasmolysis

shrinkage of bacterial cells when placed in a hypertonic solution

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Crenation

shrinkage of red blood cells when placed in a hypertonic solution

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Hypotonic

less solute than normal (water enters the cells causing them to burst)

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Plasmoptysis

bursting of bacterial cells when placed in a hypotonic solution

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Hemolysis

bursting of red blood cells when placed in a hypotonic solution

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Symbiosis

living together; organisms live in close nutritional relationships; required by one or both members

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Mutualism

of benefit to all, a relationship which organisms of two different species live in close association to the mutual benefit of each.

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Commensalism

of benefit to one, with no effect on the other, (Ex: normal flora) the symbiotic relationship of two organisms of different species in which one gains some benefit such as protection or nourishment and the other is not harmed or benefited.

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Parasitism

of benefit to one, harmful to the other, an interactive relationship between two organisms in which one is harmed and the other benefits

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Synergism

a relationship between 2 or more microorganisms which produces an effect, be it good or bad, not possible by each one alone

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Antagonism

a relationship between 2 or more microorganisms in which the presence of one inhibits the growth of the other; mutual opposition or contrary action

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Infection

the entry, establishment and multiplication of pathogenic organisms within a host

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Pathogenicity

the ability of an organism to cause infection in man; the state of producing or being able to produce pathological changes and disease

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Attenuation

a weakening in the virulence of an organism; dilution or weakening of virulence of a microorganism, reducing or abolishing pathogenicity

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Drug-fast

resistant, as in bacteria, to the action of a drug or drugs

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Factors influencing virulence

1. toxin production
2. enzymes
3. capsules
4. endospores

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Exotoxins

produced all the time & continuously released to the outside; Example: tetanus, cholera

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Endotoxins

only released when cell producing it is destroyed; Example: spinal meningitis

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Enzymes

organic catalysts; substances that speed up or slow down a chemical reaction without being destroyed or used up in the process

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Hyaluronidase

(spreading factor)- breaks down hyaluronic acid

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Coagulase

Clots plasma; cause a clot around the bacteria

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Fibrinolysin

(streptokinase)- dissolves blood clots, especially if the clot caused MI

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Capsules

Slime-layer; the membrane that surrounds some bacterial cells; a loose gel-like structure that, in pathogenic bacteria helps to protect cells from phagocytosis, thus enhancing virulence of microorganisms

84

Endospores

best means of protection, not means of reproduction, (clostridium)

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Sources of infection

1. Animals or persons currently ill of the infection (best source of infection transmission)
2. Chronic animal or human carriers
3. Environment

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Active carriers

animal or human that posses a particular an organism and transmits that organism to others after their recovery;

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Passive carriers

animal or human that posses a particular an organism and transfers it to others, even though they have never suffered from the infection it causes. Ex: Typhoid Mary (typhoid fever)

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Convalescent carrier

during recovery

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Direct transmission

a. Physical contact-STD’S
b. Droplet infection (aerosol)
c. Congenital- rubella (any disease present at birth)

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Indirect transmission

a. Food
b. Milk
c. Fomites- lifeless inanmite objects
d. Water
e. Soil
f. Vectors

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Vectors

arthropods, insects, flies, tree roaches, that are not suffering from the infection in which they are carrying

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Biological vectors

mosquitoes (blood suckers), malaria (monkeys)

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Mechanical vectors

they carry the infection on their outside shell, wings feet, ect.

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Portals of entry & exit of pathogens

1. Skin & mucous membranes- staph.
2. Respiratory tract- TB, pneumonia
3. Digestive tract- cholera, dysentery
4. Genito-urinary tract (GUT)- STD’s
5. Placenta- rubella (German measles)

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Vehicles of exit of pathogens

1. Feces- dysentery, cholera
2. Urine- U.T. infections, STD’s; purulent (cloudy) appearance
3. Semen
4. Vaginal secretions- yeast infections
5. Sputum
6. Saliva- cytomegalovirus (CID)
7. Blood- hepatitis A & B
8. Pus & lesion exudates- skin, abscesses, decubitus ulcers
9. Tears

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Factors influencing the occurrence of an infection

1. Portal of entry of the pathogens & elective localization
2. Number of organisms- greater number that attack, the more likely you are to catch it
3. Virulence of the organisms
4. Resistance of the host

97

Health or Illness= N (V)
R

formula=