Lab 30: Throat Culture/Respiratory Tract

Question 1

what are two examples of respiratory tract pathogens?

Answer 1

1. Streptococcus pneumoniae
2. Streptococcus pyogenes

Question 2

what is the presence of Streptococcus pneumoniae bacteria?

Answer 2

Gram-positive cocci in chains

Question 3

what is the rate of asymptomatic carriers of Streptococcus pneumoniae?

Answer 3

high rate

Question 4

what can Streptococcus pneumoniae cause?

Answer 4

It can cause infections of the middle ear and sinuses in children.
It can cause pneumonia, meningitis, and bacteremia.

Question 5

what is the presence of Streptococcus pyogenes bacteria?

Answer 5

Gram-positive cocci in chains

Question 6

what is the amount of asymptomatic carriers of Streptococcus pyogenes?

Answer 6

asymptomatic carriers are 1 in 10 people

Question 7

what can Streptococcus pyogenes cause?

Answer 7

It can cause:
-Strep throat (if untreated, can cause rheumatic fever)
-Skin infections: impetigo, cellulitis
-Necrotizing fasciitis: infection of connective tissue covering muscles

Question 8

what is the growth of respiratory pathogens bacteria?

Answer 8

Fastidious bacteria: it requires special nutrients to grow. it is hard to grow, and doesn’t ‘t grow on nutrient agar or TSA

Question 9

what agar do respiratory pathogens need to grow on?

Answer 9

The medium is Sheep’s Blood Agar (which is an agar with sheep’s blood in it)

Question 10

what does the blood from the agar provide and allow for respiratory pathogens?

Answer 10

-The blood provides extra nutrients
-It also allows identification: some microbes can destroy RBCs using a process called hemolysis to give specific patterns that can be used to ID unknowns

Question 11

what is hemolysis?

Answer 11

when microbes destroy RBCs to give specific patterns that can be used to ID unknowns

Question 12

what are three types of hemolysis?

Answer 12

Alpha hemolysis
Beta hemolysis
Gamma hemoylsis

Question 13

what is Alpha hemolysis? what is it caused by and what does it cause?

Answer 13

It is a partial hemolysis of RBCs.
It is caused by the production of H2O2.
It causes leakage of hemoglobin from cells and its oxidation to methemoglobin, which is green in color.

Question 14

what do the leakage of hemoglobin from cells and its oxidation to methemoglobin in alpha hemolysis cause?

Answer 14

green color

Question 15

what is beta hemolysis? what is it caused by and what does it create?

Answer 15

It is complete hemolysis of RBCs.
It is caused by exotoxins called hemolysins.
It creates a complete clearing (a halo) of RBCs around the colonies.

Question 16

what is Gamma hemolysis?

Answer 16

no hemolysis of RBCs

Question 17

what type of hemolysis does Streptococcus pyogenes perform?

Answer 17

Beta hemolysis

Question 18

what type of hemolysis does Streptococcus pneumoniae perform?

Answer 18

Alpha (usually) or
non-hemolytic (rarely)

Question 19

is Streptococcus pyogenes sensitive or resistant to Bacitracin?

Answer 19

It is sensitive (any size zone of inhibition)

Question 20

is Streptococcus pneumoniae sensitive or resistant to Bacitracin?

Answer 20

Resistant (no zone of inhibition)

Question 21

is Streptococcus pyogenes sensitive or resistant to Optochin?

Answer 21

It is resistant (less than or equal to 14 mm zone of inhibition)

Question 22

is Streptococcus pneomoniae sensitive or resistant to Optochin?

Answer 22

Sensitive (greater than 14 mm zone of inhibition)

Question 23

what group is Streptococcus pyogenes caused by?

Answer 23

GAS (Group A streptococci)

Question 24

who classified Streptococcus spp. based of the presence of different ______.

Answer 24

Rebecca Lancefield classified Streptococcus spp. based on the presence of different cell wall carbohydrate antigens (20 serotypes)

Question 25

what is the Streptococcus pyogenes Lancefiled antigen?

Answer 25

A

Question 26

what is the Streptococcus pneumoniae Lancefield antigen?

Answer 26

None

Question 27

what are the 2 goals of the lab?

Answer 27

1. Does your throat culture contain Beta hemolytic bacteria (potential pathogens like S. pyogenes or S. aureus) or Alpha hemolytic bacteria (normal microbiota or S pneumoniae)
2. Distinguish S. pneumoniae from S. pyogenes using hemolysis results and antibiotic sensitivity.

Question 28

what to we do with our throat culture?

Answer 28

-Swab our throat
-Streak it on our plate (first with swab, then bring it to another quadrant with loop, then again with a loop for the last time).
-Incubate the plates for 48 hours at 37 degrees C

Question 29

how do we view our plates for results?

Answer 29

By looking in the light from the bottom surface. Then we determine the patterns of hemolysis

Question 30

A beta hemolysis pattern may indicate an active infection, but it may also indicate someone who is a ____ carrier of a disease?

Answer 30

Healthy.

Question 31

what are healthy carriers?

Answer 31

Healthy carriers harbor the pathogen in their bodies, but they do not have symptoms of illness because the pathogen is kept in check by competing microbiota. However, they can give the pathogen to others and make them ill. This is especially a concern if a healthcare worker is a healthy carrier and they are looking after immunocompromised patients.

Question 32

what part of our throat do we sample?

Answer 32

The palatoglossal arches

Question 33

add results here