MIP: Gram Positive Pathogenic Bacteria Flashcards Preview

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Flashcards in MIP: Gram Positive Pathogenic Bacteria Deck (45):
1

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

2

2

What TLR detects flagella?

5

3

What are the major subdivisions of the Gram Positive Cocci?

Staphylococcus, Streptococcus, and Enterococcus facalis

4

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

They have lipoarabinomannan (LAM) in their cell walls

5

Why are acid-fast bacteria difficult to treat?

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

6

Where is Staph aureus found?

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

7

Why is S. aureus an apt name?

Many strains produce the anti-oxidative gold pigment, staphoxanthin

8

What hemolysis pattern is seen with S. aureus?

Beta-hemolysis

9

What is the action of coagulase?

Converts fibrinogen to fibrin and coagulates plasma

10

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

False- not in epidermis or saprophyticus

11

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

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

12

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

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

13

What host factors increase susceptibility to Staph aureus infection?

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

14

How does S. aureus's Protein A work?

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

15

What is an abscess?

Collection of pus (caused by neutrophil degranulation)

16

What is a furuncle? A carbuncle?

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

17

How do you treat abscesses, furuncles, and carbuncles?

Incising the wound, draining it, and antibiotic therapy

18

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

Alpha toxin

19

What is cellulitis?

Infection of subcutaneous layers of skin

20

What is Scalded Skin Syndrome?

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

21

What is Impetigo?

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

22

What is the cause of food poisoning?

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

23

What is the cause of toxic shock syndrome?

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

24

What are the symptoms of Toxic Shock Syndrome?

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

25

How can S. aureus cause osteomyelitis and endocarditis?

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

26

What are the symptoms and signs of Pediatric Osteomyelitis?

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

27

What is the leading cause of pediatric septic joints?

Staph aureus

28

What is a Brodie abcess?

Subacute osteomyelitis where the abcess becomes surrounded by bone tissue

29

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

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

30

What is Panton-Valentine leukocidin?

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

31

How does Staph epidermis appear on sheep blood agar?

Small white non-hemolytic colonies

32

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

True

33

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

Staph will bubble in hydrogen peroxide and strep does not

34

Where can staph epi be found?

Plastic catheters and tubing, septicemia, endocarditis

35

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

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

36

What are Lancefield Classifications based on?

Antigenic variation of C-carbohydrates and Glycerol Teichoic Acid

37

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

Group A from Group B

38

What Group is Streptococcus pyrogenes?

Group A

39

What are the hallmarks of pharyngitis?

Fever, cough, pain, and pus

40

What is pharyngitis?

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

41

What is the algorithm for diagnosing strep?

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

42

What are the Streptococcal Pyrogenic Exotoxins?

SpeA, SpeB, and SpeC

43

What is Scarlet fever and what is its cause?

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

44

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

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

45

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

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