Exam 4: Intro and Gram + cocci

Question 1

What is exotoxin?

Answer 1

it is secreted by gram + or - bacterium not the surround fluid following lysis of bacterial cell. bacteria must colonize tissue to produce enough exotoxin to be harmful

Question 2

Most exotoxins are proteins. What does this mean?

Answer 2

• the immune system can produce antibodies

- they are denatured by heat

Question 3

Exotoxins are released by every gram _____ (+ or -) genera except ______.

Answer 3

+, listeria

Question 4

exotoxins have specific targets and usually do not cause ____ or ____.

Answer 4

fever or generalized inflammation

Question 5

Type of exotoxin that acts on nerves or motor endplates to cause paralysis

Answer 5

neurotoxin

Question 6

type of exotoxin that acts on gastrointestinal tract to cause diarrhea

Answer 6

enterotoxin

Question 7

type of exotoxin that causes damage to a variety of cell types by either interfering with cell mechanisms or causing cell lysis

Answer 7

cytotoxins

Question 8

What is endotoxin?

Answer 8

Lipid A, the toxin portion of the lipopolysaccharide which is part of the outer membrane of gram - bacteria

Question 9

The immune response to endotoxin is due to _____.

Answer 9

innate immune response

*this means there is no specific target

Question 10

Can endotoxins be destroyed by heat?

Answer 10

no, they are heat stable

Question 11

What are the major categories of gram positive cocci?

Answer 11

• staphylococcus

- streptococcus

Question 12

Which of the staphylococcus species has a golden pigment?

Answer 12

staph aureus

*Aureus is a gold coin of ancient rome

Question 13

How do you differentiate between staph aureus and staph epidermidis in order to make a diagnosis?

Answer 13

staph aureus is coagulase positive while staph epidermidis is coagulase negative

Question 14

Which of the staphylococcus species is an opportunistic pathogen?

Answer 14

staph epidermidis

Question 15

What bacterial species causes the following pathogenesis:

• furuncles, carbuncles and build
• folliculitis
• toxic shock syndrome
• scalded skin syndrome
• pneumonia
• osteomyelitis
• MRSA

Answer 15

staph aureus

Question 16

Why is treatment of staph infections (both aureus and epidermidis) so difficult?

Answer 16

both species produce penicillinase and so are resistant

Question 17

Are the gram positive cocci (staphylococcus and streptococcus) part of normal flora?

Answer 17

yes

Question 18

What bacterial species is part of the normal flora of female genital tract?

Answer 18

streptococcus agalactiae

Question 19

How are streptococci species classified?

Answer 19

by hemolysis patterns - how they rupture or destroy red blood cells

Question 20

hemolytic pattern in which there is partial hemolysis with green cast around colonies of bacteria?

Answer 20

alpha hemolytic

Question 21

hemolytic pattern in which there is complete hemolysis creating clear area around colonies

Answer 21

beta hemolytic

Question 22

hemolytic pattern in which there is no hemolysis

Answer 22

gamma hemolytic

Question 23

lance field groups are sometimes used to classify what bacteria?

Answer 23

streptococci

Question 24

the more inclusive way to classify strep is to divide into 4 groups:

Answer 24

• lactic streptococci (non pathogenic, gamma hemolytic)
• fecal streptococci (enterococci)
• viridans streptococci (alpha hemolytic, tooth decay)
• beta hemolytic streptococci

Question 25

what is the major streptococcal pathogen?

Answer 25

strep pyogenes

Question 26

identifying features of strep pyogenes?

Answer 26

• produces pyrogenic exotoxin
• has a hyaluronic acid capsule
• has fibrils called M protein on cell surface

Question 27

What bacterial species causes the following pathogenesis:

• pharyngitis
• impetigo
• cellulitis
• erysipelas AKA st. Anthony’s fire
• scarlet fever
• rheumatic fever
• glomerulonephritis

Answer 27

strep pyogenes

Question 28

What gram positive cocci species are beta hemolytic

Answer 28

strep pyogenes

strep agalactiae

Question 29

What is the hemolytic pattern of strep pneumoniae?

Answer 29

alpha hemolytic

Question 30

What bacterial species is an important cause of neonatal meningitis, pneumonia, sepsis that leads to high mortality rate?

Answer 30

strep pneumoniae

Question 31

What bacterial species has a major virulence factor of a polysaccharide capsule?

Answer 31

strep pneumoniae

Question 32

If strep pneumoniae is part of the normal flora, how does it cause infection?

Answer 32

if invasive strain moves to lower lungs, it can cause pneumonia

Question 33

other than pneumonia, what other pathologies can strep pneumoniae cause?

Answer 33

meningitis, otitis media, sinusitis

Question 34

How is the strep pneumoniae diagnosis made?

Answer 34

Quellung reaction