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87 Cards in this Set

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  • Back
The cohabitation of normal flora and human body is an example of ___.
symbiosis
Symbiosis in which both parties benefit is ___.
mutualism
Symbiosis in which one party gains and the other is unaffected is called ___.
commensalism
Symbiosis in which one party gains and the other is harmed is called ___.
parasitism
What is the difference between 'infection' and 'disease'?
Infection = invasion or colonization of the body by a pathogenic microorganism

Disease = damage or injury to body that impairs function
Define pathogenic.
disease causing
The naming convention for bacteria is ___ ___ or _ ___.
Genus species or G. species
Define strain.
A population of bacteria descended from a single cell in clonal fashion.
What does pathogenicity refer to? Is it qualitative or quantitative?
The ability of an organism to cause disease. It is qualitative.
A ___ is capable of harming a normal host (an example being ___ ___). An ___ ___ harms a compromised host (an example being ___ ___).
pathogen: Mycobacterium tuberculosis

opportunistic pathogen: Pseudomonas aeruginosa
What does virulence measure? How can it be expressed? Is it qualitative?
Virulence is a measure of pathogenicity. It can be expressed as the cell number that will elicit a pathogenic response in a host in a given time period. No,it is QUANTITATIVE.
What are the four classifications of bacterial infection?
1) primary infection
2) secondary
3) subclinical
4) nosocomial
Define secondary infection.
Infection caused by an opportunistic parthogen after a primary infection.
Define subclinical infection.
No apparent symptoms.
Define nosocomial infection.
Acquired as a consequence of hospitalization.
What are the three classifications of bacterial infection that pertain to location?
local, systemic (generalized), focal
What are the 6 key factors influencing the outcome of a bacterial infection?
1) underlying disease or infection (eg AIDS)
2) stress
3) poor nutrition
4) age
5) immunosuppressive therapy
6) genetics of the host defence system
What is the most numberous and obvious microbial component of the normal flora?
Bacteria
What does the normal flora contain besides bacteria?
come methanogenic Archaea and a few eukaryotic fungi
How do bacteria of the normal flora benefit from us?
nutrients, stable environment / protection, mode of transport
In what three main ways do we benefit from the normal flora?
- inhibits bacterial infection
- pH, nutrients, O2 levels
- nutritional synergisms
- synthesis of vitamins
- steroid metabolism
- organic acid production
- stimulation of immune system
- glycosidase reactions
What are two disadvantages of the normal flora?
pathogenic potential when introduced into other locations
- ie E. coli

production of intestinal gas
What 5 vitamins do the normal flora produce?
thiamin
riboflavin
pyridoxine
vitamin B12, K
What gases do the normal flora produce?
CO2
CH4
H2
What odor-causing molecules are produced by the normal flora?
skatole
butyric acid
H2S
NH3
amines
indole
What organic acids are produced by the normal flora?
butryic acid
acetic acid
propionic acid
Is the fetal environment stable before birth, or are babies born with normal flora?
It is sterile. Normal flora acquired shortly after birth
What factors affect the composition of the normal flora?
Diet
Infection
Oral antiobiotic therapy
What is colitis caused by?
The overgrowth of Clostridium difficile
What determines the location of the normal flora?
Bacteria's tissue preference for colonization
Interaction with human receptors expressed at specific locations
Biofilms tend to attract large amounts of bacteria to one site
What are the three classifications of bacterial infection that pertain to location?
local, systemic (generalized), focal
What are the 6 key factors influencing the outcome of a bacterial infection?
1) underlying disease or infection (eg AIDS)
2) stress
3) poor nutrition
4) age
5) immunosuppressive therapy
6) genetics of the host defence system
What is the most numberous and obvious microbial component of the normal flora?
Bacteria
What does the normal flora contain besides bacteria?
come methanogenic Archaea and a few eukaryotic fungi
How do bacteria of the normal flora benefit from us?
nutrients, stable environment / protection, mode of transport
In what three main ways do we benefit from the normal flora?
- inhibits bacterial infection
- pH, nutrients, O2 levels
- nutritional synergisms
- synthesis of vitamins
- steroid metabolism
- organic acid production
- stimulation of immune system
- glycosidase reactions
What are two disadvantages of the normal flora?
pathogenic potential when introduced into other locations
- ie E. coli

production of intestinal gas
What 5 vitamins do the normal flora produce?
thiamin
riboflavin
pyridoxine
vitamin B12, K
What gases do the normal flora produce?
CO2
CH4
H2
What odor-causing molecules are produced by the normal flora?
skatole
butyric acid
H2S
NH3
amines
indole
What organic acids are produced by the normal flora?
butryic acid
acetic acid
propionic acid
Is the fetal environment stable before birth, or are babies born with normal flora?
It is sterile. Normal flora acquired shortly after birth
What factors affect the composition of the normal flora?
Diet
Infection
Oral antiobiotic therapy
What is colitis caused by?
The overgrowth of Clostridium difficile
What determines the location of the normal flora?
Bacteria's tissue preference for colonization
Interaction with human receptors expressed at specific locations
Biofilms tend to attract large amounts of bacteria to one site
Average area of human adult's skin
2 m^2
What areas of skin are microorganisms associated with?
sweat glands, armpit, genital region, between toes, upper region of hair follicles
What microbial nutrients do the sebaceous glands secrete?
urea, amino acids, salts, lactic acid, lipids
Give two examples of commensal skin flora
Staphylococcus epidermidis
Micrococcus sp.
Give an example of a potentially pathogenic skin flora
Staphylococcus aureus (around nostrils)
What affects skin flora?
weather,
age,
hygiene
diet
Why is saliva not a good culture for bacteria?
Few nutrients
lysozyme
lactoperoxidase
What does lysozyme do to bacteria?
Weakens cell wall by cleaving glycosidic linkages in peptidoglycan
What does lactoperoxidase do to bacteria?
kills bacteria, creating singlet oxygen
What makes the mouth a good site for flora?
food particles
epithelial debrees
As the teeth appear in an infant, there is a shift toward ___ bacteria
anaerobic, adapted to gingival crevices and tooth surface
Define plaque
a type of complex biofilm on tooth surfaces
What is the name given to the adherent substances produced by organisms in plaque?
glucans
Define 'dental caries' (cavities)
destruction of enamel, dentin, or cementum of teeth caused by acid-producing bacteria in plaque
What organism is most associated with dental caries
Streptococcus mutans
Define periodontal disease. What is the most common form?
bacterial infection that affects supporting structure of teeth. Ginvitis
What are the most common infectious diseases in the world?
periodontal diseases and caries
What does the GI tract consist of?
stomach, small and large intestine
The majority of GI tract flora are __robic bacteria. Three examples.
anaerobic
E. coli
Bacteroides
Lactobacillus
E. coli has what type of respiration?
facultative anaerobe
Bacteroides has what type of respiration?
strict anaerobe
Lactobacillus has what type of respiration?
aerotolerant anaerobe
How high is bacterial count in stomach? Why?
Low. Acidic
One example of a bacteria colonizing stomach wall
Helicobacter pylori (gastric ulcers)
What does the small intestine consist of?
Duodenum
Jejunum
Ileum
What does the large intestine consist of?
Colon
What major physiological process occurs in stomach? pH?
Secretion of acid
Digestion of macromolecules
pH=2
What major physiological process occurs in small intestine? pH?
Continued digestion
Adsorption of monosaccharides, amino acids, fatty acids, water
pH=4-5
What major physiological process occurs in large intestine? pH?
Adsorption of bile acids, vitamin B12
pH=7
What bacteria inhabit small intestine?
Enterococci
Lactobacilli
What bacteria accounts for 90% of intestinal flora within a week of infant feeding?
Bifidobacteria
Describe nostril flora
- always heavily colonized
- predominantly Staphylococcus epidermidis
- sometimes Staphylococcus aureus (potential pathogen)
describe sinus flora
normally sterile
describe LRT flora
virtually free. Cilia sweep bacteria upward, then expelled by sneezing
describe URT flora
- large number
- around mucous areas
Give two diseases that can damage resp tract epithelium
bronchitis or viral pneumonia
What causes whooping cough?
Bordotella pertussis colonizing the tracheal epithelium
Is urine normally sterile?
yes
What does Lactobaciluus sp. do?
Colonizes vagina, lowers pH, confers protection
What produces yeast infection?
antibiotic therapy removing natural bacteria, leading to colonization by candida
Define gnotobiotic
germ-free
Give six characteristics of gnotobiotic animals
abnormal anatomy/physiology
underdeveloped lymphatic tissue
poor immune system
thin intestinal wall
low antibody titer
higher susceptibility to pathogens
reduced susceptibility to certain disease processes (ie dental caries)