MIP: Gram Positive Pathogenic Bacteria

Question 1

What TLR detects peptidoglycan and lipoproteins in Gram + bacterial cell walls?

Answer 1

2

Question 2

What TLR detects flagella?

Answer 2

5

Question 3

What are the major subdivisions of the Gram Positive Cocci?

Answer 3

Staphylococcus, Streptococcus, and Enterococcus facalis

Question 4

Why can’t acid-fast organisms be Gram stained?

Answer 4

They have lipoarabinomannan (LAM) in their cell walls

Question 5

Why are acid-fast bacteria difficult to treat?

Answer 5

They have a very slow doubling time and they have a high mutation rate and LAM

Question 6

Where is Staph aureus found?

Answer 6

It is part of normal and transient flora in humans and is foudn in moist pllaces (skin, armpit, nasopharynx, nares, groin)

Question 7

Why is S. aureus an apt name?

Answer 7

Many strains produce the anti-oxidative gold pigment, staphoxanthin

Question 8

What hemolysis pattern is seen with S. aureus?

Answer 8

Beta-hemolysis

Question 9

What is the action of coagulase?

Answer 9

Converts fibrinogen to fibrin and coagulates plasma

Question 10

True or False: Coagulase is found in all Staphylococcus bacteria.

Answer 10

False- not in epidermis or saprophyticus

Question 11

What is the selectivity and differential capacity of a mannitol agar plate? How will S. aureus streak?

Answer 11

The selective component is salt, and the differential components are mannitol and phenol red; S. aureus turns the plate from red to yellow

Question 12

What is the spectrum of disease that is caused by S. aureus?

Answer 12

Boils, furnicules, styes, impetigo, osteomyelitis, cellulitis, mastitis, UTIs, acute endocarditis, meningitis, TSS, food poisoning, scaleded skin syndrome, pneumonia, empyema, septic arthritis

Question 13

What host factors increase susceptibility to Staph aureus infection?

Answer 13

Breaches in the skin, immunological defects, foreign bodies, close quarters coupled with poor hygiene, previous damage to tissues

Question 14

How does S. aureus’s Protein A work?

Answer 14

It binds to the Fc portion of IgG and prevents its binding to phagocyte and facilitating of phagocytosis

Question 15

What is an abscess?

Answer 15

Collection of pus (caused by neutrophil degranulation)

Question 16

What is a furuncle? A carbuncle?

Answer 16

A furuncle is an abscess into subcutaneous tissue and a carbuncle is multiple contagious abscesses

Question 17

How do you treat abscesses, furuncles, and carbuncles?

Answer 17

Incising the wound, draining it, and antibiotic therapy

Question 18

What S. aureus toxin causes hemolysis and necrosis of the skin?

Answer 18

Alpha toxin

Question 19

What is cellulitis?

Answer 19

Infection of subcutaneous layers of skin

Question 20

What is Scalded Skin Syndrome?

Answer 20

Charecterized by fever, large bullae, and an erythematous macular rash, all induced by epidermolytic exotoxins (exfoliatin A and B) which are proteases that cleave desmoglein-1 and can cause detachment within the epidermal layer

Question 21

What is Impetigo?

Answer 21

A very contagious infection in which small vesicles develop into pustules which crust over to become honey-colored and flaky

Question 22

What is the cause of food poisoning?

Answer 22

Staph contaminates food and secretes enterotoxins (SEA, SEB, SEC1) stimulating the vagus nerve endings in the stomach and causing super-antigen effects that result in excess of IL-2

Question 23

What is the cause of toxic shock syndrome?

Answer 23

The secretion of TSST-1 by Staph that acts as a super-antigen

Question 24

What are the symptoms of Toxic Shock Syndrome?

Answer 24

Fever, nausea, vomiting, and diarrhea followed by rash and exfoliation–> blood pressure drops, Multi System Organ Failure, death

Question 25

How can S. aureus cause osteomyelitis and endocarditis?

Answer 25

S. aureus can hijack a neutrophil by resisting destruction following phagocytosis, and it is safe from antibiotics and now can be spread through the neutrophil throughout the body

Question 26

What are the symptoms and signs of Pediatric Osteomyelitis?

Answer 26

Limp, bone pain, fever, leukocytosis, and elevation of erythrocyte sedimentation rate and C-reactive protein

Question 27

What is the leading cause of pediatric septic joints?

Answer 27

Staph aureus

Question 28

What is a Brodie abcess?

Answer 28

Subacute osteomyelitis where the abcess becomes surrounded by bone tissue

Question 29

What is infective endocarditis? What is the difference between acute and chronic?

Answer 29

Inflammation of heart valves or around congenital heart defects that shows up as bacteremia and fever from colonization of a valve; Acute is due to staph aureus and more severe presenting than chronic, which is caused by coagulase-negative staph infections

Question 30

What is Panton-Valentine leukocidin?

Answer 30

A protein made by staph in the lungs that forms pores in cells that line the alveolar space, allowing fluid to accumulate inside of the tissue. PVL also causes activation of PMNs and macrophages and PMN necrosis-- causes hemorrhagic, necrotic pneumonia

Question 31

How does Staph epidermis appear on sheep blood agar?

Answer 31

Small white non-hemolytic colonies

Question 32

True or False: Staph epidermis is coagulase negative and catalase positive

Answer 32

True

Question 33

How could you chemically distinguish between a Staph and Strep infection?

Answer 33

Staph will bubble in hydrogen peroxide and strep does not

Question 34

Where can staph epi be found?

Answer 34

Plastic catheters and tubing, septicemia, endocarditis

Question 35

What are the hemolysis patterns that are exhibited by strains of Streptococcus?

Answer 35

Alpha hemolysis (erythrocytes not destroyed, but greenish discoloration due to organisms' effect on hemoglobin; Beta-hemolysis (erythrocyte destruction); gamma hemolysis (non-hemolytic)

Question 36

What are Lancefield Classifications based on?

Answer 36

Antigenic variation of C-carbohydrates and Glycerol Teichoic Acid

Question 37

Bacitracin can be used to distinguish what two types of Strep?

Answer 37

Group A from Group B

Question 38

What Group is Streptococcus pyrogenes?

Answer 38

Group A

Question 39

What are the hallmarks of pharyngitis?

Answer 39

Fever, cough, pain, and pus

Question 40

What is pharyngitis?

Answer 40

Pharyngeal inflammation and petechiae of soft palate, tonsils, with possible hard palate involvement

Question 41

What is the algorithm for diagnosing strep?

Answer 41

If more than one of the following criteria are met (tonsilar exudates, tender cervical adenopathy, absence of cough, fever) then do a rapid strep test. If the test is positive then treat with antibiotics

Question 42

What are the Streptococcal Pyrogenic Exotoxins?

Answer 42

SpeA, SpeB, and SpeC

Question 43

What is Scarlet fever and what is its cause?

Answer 43

A bacterial illness that often [resents with a distinctive rash made up of tiny pink-red spots that cover the whole body and it is caused by SpeA by Group A Strep

Question 44

How can acute rheumatic fever be part of post-streptococcal sequelae?

Answer 44

A region of the M protein shares some epitope with heart muscle--> molecular mimicry

Question 45

What are the theories of the pathophysiology of Post-Streptococcal glomerulonephritis?

Answer 45

IgG-streptococcal antigen complexes depositing on glomerular tissue or Cross-reactivity between unidentified strep antigens and glomerular membrane components