Lab 45

Question 1

Staphylococcus aureus is gram __________ (+/-), and coagulase __________(+/-)

Answer 1

gram positive, coagulase positive

Question 2

After you have observed a gram-positive coccus, what additional information do you need before performing a coagulase test?

Answer 2

You must preform a catalase test and if it’s positive then you preform a coagulase test

Question 3

List three identifying characteristics of Staphylococcus aureus

Answer 3

gram positive, cocci, and catalase positive

Question 4

List three identifying characteristics of Staphylococcus aureus

Answer 4

gram positive, cocci, and catalase positive

Question 5

List three factors that protect the skin from infection

Answer 5

high salt concentration, sebum, and the dry layer of keratin containing cells that make up the epidermis

Question 6

What is coagulase and how is it related to pathogenicity

Answer 6

it’s an enzyme that clots the fibrin in the blood. It;s related to pathogenicity because both coagulase an bacteria are able to withdraw themselves inside a clot to prevent the host from killing them

Question 7

Assume you isolated S. aureus from your skin. How would you determine whether it is penicillin resistant?

Answer 7

You could preform a disk diffusion method test or grow it in a broth

Question 8

Know how to use appendix H!

Answer 8

;)

Question 9

The most common genera on skin are ____________ and _____________

Answer 9

Propionibacterium and Staphylococcus

Question 10

Most bacteria on the skin are ____________ and _____________.

Answer 10

gram- positive and salt- tolerant

Question 11

Mannitol salt agar is ____________ (selective/differential) for salt- tolerant organisms and is ____________ (selective/differential) in that mannitol- fermenting organisms will produce acid, turning the indicator in the medium yellow

Answer 11

selective, differential

Question 12

______________ is part of the normal micro-biota of the skin and is also considered a pathogen

Answer 12

Staphylococcus aureus

Question 13

What does Staphylococcus aureus produce?

Answer 13

coagulase

Question 14

What solution is needed for a catalase test?
What indicates a positive test?
A negative test?

Answer 14

H2O2
bubbles = catalase- positive;
no bubbles = catalase-negative;

Question 15

What solution is needed for a coagulase test?
What indicates a positive test?
A negative test?

Answer 15

Rehydrated coagulase plasma
clumping = coagulase- positive;
no clumping = coagulase-negative;

Question 16

Where are transient microbiota found?

Answer 16

on hands and arms in contact with the environment

Question 17

Propionibacterium live in _______________ The propionic acid they produce maintains the pH of the skin between __________, which suppresses the growth of other bacteria.

Answer 17

hair follicles on sebum from oil glands, 3 and 5

Question 18

A test for the presence of coagulase is used to distinguish _____________________________

Answer 18

S. aureus from other species of Staphylococcus.

Question 19

In this experiment we are trying to isolate a ________________________________

Answer 19

a catalase- positive, gram- positive coccus.