Microbiology Exam 2 Flashcards
Exogenous
An infection in which the causative agent comes from outside the body
Endogenous
An infection which is caused by microorganisms which are normally present within the body
Acute
an infection of sudden onset and short duration (meningococcemia)
Chronic
an infection of slow onset and long duration (Alzheimer’s)
Communicable
An infection capable of being transmitted, either directly or indirectly, from host to host. Contagious means highly communicable
Endemic
An infection that is constantly present to a greater or lesser degree in a community Ex: cold flu
Epidemic
An infection which attacks a large number of people in a community in a short period of time
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
Sporadic
An infection which occurs only occasionally (now and then) in a community (Legionnaire’s disease; 4 corners region=Hantavirus)
Primary
the initial (first) infection of a mixed infection
Mixed
an infection due to two or more organisms ex: 2 or more infections occurring at the same time
Secondary
the second and generally more complicating infection in a mixed infection
Local
an infection in which the pathogenic organisms remain confined to a particular area (abscessed tooth)
Focal
an infection confined to a particular area, but from which the bacteria spread to other parts of the body
General
Infection throughout, spread generally over the body by the bloodstream or lymphatic system (septicemia/sepsis)
Bacteremia
a condition in which bacteria are in the bloodstream but are not multiplying there
Septicemia
Invasion of the bloodstream by pathogenic organisms with their subsequent multiplication therein. Common name is “blood poisoning” (sepsis)
Toxemia
the presence of toxins (poisonous substances) in the blood
Terminal
an infection which occurs during the course of a chronic disease and causes death
Contamination
The presence of infectious material, without a reaction necessarily being produced. This term can also refer to inanimate objects (fomite)
Infestation
The invasion of the body by macroscopic parasites; those able to be seen with the unaided eye (maggots)
Virulence
the ability of a microorganism to produce disease. Attenuation implies a weakening or reduction in the virulence of a microorganism
Zoonotic
Diseases caused by infectious agent that can be transmitted between (or are shared by) animals and humans (malaria; encephalitis)
Nosocomial
A hospital-acquired infection; one obtained while in the hospital (staph)
Pyemia
Literally, pus in the blood; a form of septicemia cause by cryogenic (pus-forming) bacteria
Fulminating
A sudden, severe and overwhelming infection, such as spinal meningitis
Generalized
infection throughout the body, having been spread by the bloodstream or lymphatic system
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)
Inapparent
an infection in which the clinical symptoms are not recognized or immediately detectable (TB)
Typical mumps
an infection in which all the symptoms are easily recognized (rubella)
Atypical
An infection in which all symptoms are not easily recognizable, meaning that it could be confused with another infection
Pathogens
any microorganism that causes disease in man. A non-pathogen does not cause disease in man
Types of Pathogens
Normal Flora
Opportunists
Strict (obligate) pathogens
Normal Flora/ Indigenous flora
Microorganisms that live and grow in and on the human body. Most are non-pathogens
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
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)
Bacterial typical reproduction is by?
binary fission (simple transverse division) an asexual means
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
asexual reproduction
has everything it needs to reproduce on its own
Bacterial colony
a visible group of bacteria growing on a solid medium, presumably arising from a single microorganism (nutrient broth, blood agar)
What are the conditions affecting bacterial growth?
- Food requirements
- Oxygen requirements
- Moisture (water) requirements
- pH
- Temperature requirements
- Effect of light on bacterial growth
- Osmotic pressure
Autotrophic bacteria
self nourishing bacteria; obtain there food from an organic matter, does not contain carbon
Heterotrophic bacteria
other than self nourishing; organisms that must obtain their nourishment from complex organic matter; does contain carbon
Strict (obligate) saprophytes
an organism that can only survive on dead or decaying organic matter
Strict (obligate) parasite
an organism that is completely dependent on its living host for survival
Strict (obligate) aerobe
a microbe that can only live in the presence of free oxygen (Humans)
Strict (obligate) anaerobe
a microbe that can only survive in the absence of free oxygen (Clostridium/ gang-green)
Microaerophilic
a microorganism that requires very little free oxygen (a level less that is required for humans)
pH
percentage of Hydrogen ion in solution; slightly alkaline for most pathogens
Facultative bacteria
organisms that can live in the presence or absense or oxygen
Minimum temperature
lowest temperature at which any organism could live
Maximum temperature
highest temperature at which any organism could live
Optimum temperature
temperature at which any organism grows best at
Psychrophiles (cryophiles)
organisms that grow best at cold temperatures below 20 degrees C
Mesophiles
most pathogens organisms that prefer moderate temperature and develop best at temperatures between 20 and 40 degrees C
Thermophiles
organisms that thrive best at high temperatures, above 40 degrees C
Effect of light on bacterial growth
UV light is bactericidal
Osmotic pressure
pressure that develops when two solutions of different concentrations are separated by a semi-permeable membrane
Isotonic
this solution is important to study bacterial cells & red blood cells
Hypertonic
excess solute (water leaves the cells cause shrinkage)
Plasmolysis
shrinkage of bacterial cells when placed in a hypertonic solution
Crenation
shrinkage of red blood cells when placed in a hypertonic solution
Hypotonic
less solute than normal (water enters the cells causing them to burst)
Plasmoptysis
bursting of bacterial cells when placed in a hypotonic solution
Hemolysis
bursting of red blood cells when placed in a hypotonic solution
Symbiosis
living together; organisms live in close nutritional relationships; required by one or both members
Mutualism
of benefit to all, a relationship which organisms of two different species live in close association to the mutual benefit of each.
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.
Parasitism
of benefit to one, harmful to the other, an interactive relationship between two organisms in which one is harmed and the other benefits
Synergism
a relationship between 2 or more microorganisms which produces an effect, be it good or bad, not possible by each one alone
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
Infection
the entry, establishment and multiplication of pathogenic organisms within a host
Pathogenicity
the ability of an organism to cause infection in man; the state of producing or being able to produce pathological changes and disease
Attenuation
a weakening in the virulence of an organism; dilution or weakening of virulence of a microorganism, reducing or abolishing pathogenicity
Drug-fast
resistant, as in bacteria, to the action of a drug or drugs
Factors influencing virulence
- toxin production
- enzymes
- capsules
- endospores
Exotoxins
produced all the time & continuously released to the outside; Example: tetanus, cholera
Endotoxins
only released when cell producing it is destroyed; Example: spinal meningitis
Enzymes
organic catalysts; substances that speed up or slow down a chemical reaction without being destroyed or used up in the process
Hyaluronidase
(spreading factor)- breaks down hyaluronic acid
Coagulase
Clots plasma; cause a clot around the bacteria
Fibrinolysin
(streptokinase)- dissolves blood clots, especially if the clot caused MI
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
Endospores
best means of protection, not means of reproduction, (clostridium)
Sources of infection
- Animals or persons currently ill of the infection (best source of infection transmission)
- Chronic animal or human carriers
- Environment
Active carriers
animal or human that posses a particular an organism and transmits that organism to others after their recovery;
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)
Convalescent carrier
during recovery
Direct transmission
a. Physical contact-STD’S
b. Droplet infection (aerosol)
c. Congenital- rubella (any disease present at birth)
Indirect transmission
a. Food
b. Milk
c. Fomites- lifeless inanmite objects
d. Water
e. Soil
f. Vectors
Vectors
arthropods, insects, flies, tree roaches, that are not suffering from the infection in which they are carrying
Biological vectors
mosquitoes (blood suckers), malaria (monkeys)
Mechanical vectors
they carry the infection on their outside shell, wings feet, ect.
Portals of entry & exit of pathogens
- Skin & mucous membranes- staph.
- Respiratory tract- TB, pneumonia
- Digestive tract- cholera, dysentery
- Genito-urinary tract (GUT)- STD’s
- Placenta- rubella (German measles)
Vehicles of exit of pathogens
- Feces- dysentery, cholera
- Urine- U.T. infections, STD’s; purulent (cloudy) appearance
- Semen
- Vaginal secretions- yeast infections
- Sputum
- Saliva- cytomegalovirus (CID)
- Blood- hepatitis A & B
- Pus & lesion exudates- skin, abscesses, decubitus ulcers
- Tears
Factors influencing the occurrence of an infection
- Portal of entry of the pathogens & elective localization
- Number of organisms- greater number that attack, the more likely you are to catch it
- Virulence of the organisms
- Resistance of the host
Health or Illness= N (V)
R
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