Exercise 17, 18, 19

question

Why is the skin a generally inhospitable environment for microorganisms?

answer

-dry layers of keratin, that make up the epidermis
-sebum, secreted by oil glands
-salts in perspiration

question

Where is transient bacteria present?

answer

hands and arms in contact with environment

question

What microbes are more present in moist areas?

answer

staphylococcus and corynebacterium

question

What microbes are more present in oily areas?

answer

Propionibacterium

question

Where does propionibacterium live? what does it produce?

answer

lives in hair follicles on sebum from oil glands

-Produces propionic acid

question

Propionic acid

answer

maintains the pH of the skin between 3 and 5

question

What is most bacteria on the skin?

answer

-gram positive and salt-tolerant
-S. aureus and S. epidermidis

question

What does S. aureus produce?

answer

Coagulase

question

Coagulase

answer

coagulates (clots) fibrin in the blood, is pathogenic

question

upper respiratory tract

answer

nose, pharynx, larynx, middle ear, and eustachian tubes

question

lower respiratory tract

answer

trachea, bronchi, alveoli

question

What bacteria can normally be found in the throat microbiome?

answer

Staphylococcus, Streptococcus, Neisseria, and Haemophilus

question

How is infection minimized in the upper respiratory tract?

answer

microbial antagonism

question

microbial antagonism

answer

Certain microorganisms of the normal microbiota suppress the growth of other microorganisms through competition for nutrients and production of inhibitory substances.

question

Normal genera in healthy lungs?

answer

Prevotella, Veillonella, Streptococcus, and Pseudomonas

question

Streptococcal species

answer

gram-positive and catalase-negative

-predominant organisms in throat cultures
-identified by biochemical characteristics

question

Hemolytic reactions

answer

based on hemolysins that are produced by streptococci while growing on blood-enriched agar

question

Blood agar

answer

5% defibrinated sheep blood
0.5% sodium chloride

question

Alpha-hemolysis

answer

Green, cloudy zone around the colony. Partial destruction of red blood cells is due to bacteria-produced hydrogen peroxide

question

beta hemolysis

answer

Complete hemolysis, giving a clear zone with a clean edge around the colony

question

gamma hemolysis

answer

No hemolysis, and no change in the blood agar around the colony

question

What hemolysis are frequently pathogens?

answer

beta-hemolytic streptococci

question

Optochin inhibition

answer

with an optochin disk is used to identify a pathogen

question

What zone of inhibition usually indicates optochin sensitivity?

answer

greater than 15 mm

question

Bile solubility

answer

used to distinguish S. pneumoniae from the other alpha-hemolytic streptococci

question

What will happen after the addition of bile salts?

answer

Sodium deoxycholate activiates an enzyme that destroys the cell wall, and the cell lyse- colonies will disappear after the addition of bile salts.

question

bacitracin

answer

antibiotic

question

mouth microbiome

answer

contains millions of bacteria in each milliliter of saliva

question

Streptococcus mutans, S. saivarius and S. sanguinis produce sticky polysaccharides from_____

answer

sucrose

question

dextran capsule

answer

S. mutans and S. sanguinins polymerization of glucose to form a dextran capsule

Enables the bacteria to adhere to surfaces in the mouth

question

Fructose released from the sucrose is fermented to produce

answer

lactic acid

question

Enzymes of S. salivarius have similar specificity for sucrose but fructose is polymerized into __________ and the liberated glucose is fermented.

answer

levan

question

what bacteria colonizes the surface of the tonge?

answer

S. salivarius

question

what bacteria colonizes the teeth?

answer

S. sanguinins and S. mutans

question

dental plaque

answer

Masses of bacterial cells, dextran and debris

question

MSB agar

answer

inhibits growth of most oral bacteria, except S. mutans

question

What does oral streptococci require?

answer

...

1 of 37

question

Why is the skin a generally inhospitable environment for microorganisms?

answer

-dry layers of keratin, that make up the epidermis
-sebum, secreted by oil glands
-salts in perspiration

question

Where is transient bacteria present?

answer

hands and arms in contact with environment

question

What microbes are more present in moist areas?

answer

staphylococcus and corynebacterium

question

What microbes are more present in oily areas?

answer

Propionibacterium

question

Where does propionibacterium live? what does it produce?

answer

lives in hair follicles on sebum from oil glands

-Produces propionic acid

question

Propionic acid

answer

maintains the pH of the skin between 3 and 5

question

What is most bacteria on the skin?

answer

-gram positive and salt-tolerant
-S. aureus and S. epidermidis

question

What does S. aureus produce?

answer

Coagulase

question

Coagulase

answer

coagulates (clots) fibrin in the blood, is pathogenic

question

upper respiratory tract

answer

nose, pharynx, larynx, middle ear, and eustachian tubes

question

lower respiratory tract

answer

trachea, bronchi, alveoli

question

What bacteria can normally be found in the throat microbiome?

answer

Staphylococcus, Streptococcus, Neisseria, and Haemophilus

question

How is infection minimized in the upper respiratory tract?

answer

microbial antagonism

question

microbial antagonism

answer

Certain microorganisms of the normal microbiota suppress the growth of other microorganisms through competition for nutrients and production of inhibitory substances.

question

Normal genera in healthy lungs?

answer

Prevotella, Veillonella, Streptococcus, and Pseudomonas

question

Streptococcal species

answer

gram-positive and catalase-negative

-predominant organisms in throat cultures
-identified by biochemical characteristics

question

Hemolytic reactions

answer

based on hemolysins that are produced by streptococci while growing on blood-enriched agar

question

Blood agar

answer

5% defibrinated sheep blood
0.5% sodium chloride

question

Alpha-hemolysis

answer

Green, cloudy zone around the colony. Partial destruction of red blood cells is due to bacteria-produced hydrogen peroxide

question

beta hemolysis

answer

Complete hemolysis, giving a clear zone with a clean edge around the colony

question

gamma hemolysis

answer

No hemolysis, and no change in the blood agar around the colony

question

What hemolysis are frequently pathogens?

answer

beta-hemolytic streptococci

question

Optochin inhibition

answer

with an optochin disk is used to identify a pathogen

question

What zone of inhibition usually indicates optochin sensitivity?

answer

greater than 15 mm

question

Bile solubility

answer

used to distinguish S. pneumoniae from the other alpha-hemolytic streptococci

question

What will happen after the addition of bile salts?

answer

Sodium deoxycholate activiates an enzyme that destroys the cell wall, and the cell lyse- colonies will disappear after the addition of bile salts.

question

bacitracin

answer

antibiotic

question

mouth microbiome

answer

contains millions of bacteria in each milliliter of saliva

question

Streptococcus mutans, S. saivarius and S. sanguinis produce sticky polysaccharides from_____

answer

sucrose

question

dextran capsule

answer

S. mutans and S. sanguinins polymerization of glucose to form a dextran capsule

Enables the bacteria to adhere to surfaces in the mouth

question

Fructose released from the sucrose is fermented to produce

answer

lactic acid

question

Enzymes of S. salivarius have similar specificity for sucrose but fructose is polymerized into __________ and the liberated glucose is fermented.

answer

levan

question

what bacteria colonizes the surface of the tonge?

answer

S. salivarius

question

what bacteria colonizes the teeth?

answer

S. sanguinins and S. mutans

question

dental plaque

answer

Masses of bacterial cells, dextran and debris

question

MSB agar

answer

inhibits growth of most oral bacteria, except S. mutans

question

What does oral streptococci require?

answer

...

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