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CRRAB Week 3 > Microbiology for Midterm > Flashcards

Microbiology for Midterm Flashcards

1
Q

What are the normal biota of the CV system?

A

Nothing - privileged site

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2
Q

What valves does IE most often occur with?

A

Mitral or Aortic

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3
Q

What are the signs and symptoms associated with IE?

A

Fever, anemia, abnormal heartbeat, abdominal/side pain, looks ill, petechiae, septic emboli, Roth’s spots, splinter hemorrhages
Subacute - enlarged spleen

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4
Q

How can dental procedures lead to infectious endocarditis?

A

Strep. viridian’s usually resides in the normal flora of the mouth so a dental procedure could give them a good area to enter the bloodstream

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5
Q

What does viridians do on blood agar plates?

A

Alpha-hemolytic (green)

-Common among normal flora, particularly in the oral cavity

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6
Q

What organisms typically cause acute endocarditis?

A

Staph aureus

Sometimes: Strep pyogenes

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7
Q

What is the clinical course of acute endocarditis?

A
  • Hectically febrile (fever comes and goes)
  • Rapidly damages cardiac structures
  • Seeds infection in distal sites through sepsis
  • If untreated, progresses to death within weeks
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8
Q

What organisms typically cause subacute endocarditis?

A

Strep viridans, Enterococcus

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9
Q

What is the clinical course of acute endocarditis?

A
  • Indolent (slow, little pain) course
  • Causes structural damage slowly
  • Rarely seeds infection at distal sites
  • Gradually progressive
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10
Q

Gamma hemolysis?

A

Doesn’t damage RBC, no color change, but growth

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11
Q

Alpha hemolysis?

A
  • Strep. viridans.
  • Partial degradation of RBC
  • Color change/oxidation and green
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12
Q

Beta hemolysis?

A
  • Group A strep (streptoccus pyogenes)

- Completely destroys RBCs

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13
Q

What are the portals of entry for IE?

A
  • Oral cavity
  • Skin
  • Upper respiratory tract
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14
Q

What are the areas of local infection for IE?

A
  • Mitral valve
  • Tricuspid valve (injection drug use)
  • Prosthetic valves
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15
Q

What groups have the highest rates of IE?

A

IV drug users

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16
Q

How to make initial IE diagnosis?

A

Patient presenting with fever and valvular abnormalities

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17
Q

How do you make further IE diagnosis?

A
  • Screen blood cultures

- Look for otherwise-unexplained arterial emboli & cardiac valvular incompetence

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18
Q

What is the fever usually in subacute infectious endocarditis?

A

Less than 103F

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19
Q

What is the fever usually in acute infectious endocarditis?

A

Between 103-104F

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20
Q

How do you know you have a positive result with the Duke Criteria?

A
  • 2 major criteria are met
  • 1 major and 3 minor criteria are met
  • 5 minor criteria are met
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21
Q

What are the two Duke major criteria?

A
  1. Positive blood culture (contamination issues) All must have same organism
  2. Evidence of endocardial involvement
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22
Q

What are the 5 Duke Minor Criteria?

A
  1. Predisposition (heart condition or injection drug use)
  2. Fever above 38C (100.3F)
  3. Vascular phenomena (arterial emobli, Janeway lesions - nontender, erythematous lesions on hands and soles)
  4. Immunological phenomena (Osler node - painful, red raised lesions on hands and feet, Roth;s spots, rheumatic fever, etc.)
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23
Q

What drugs should you use to treat Acute IE?

A

Gear treatment toward staph infection with concern for MRSA or coat-neg. staph

  1. Nafcillin or Oxacillin +/- Gentamicin or Tobramycin
  2. Vancomycin + Gentamicin
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24
Q

What drugs should you use to treat Subacute IE?

A

Gear treatment toward strep infection.

  1. Ampicillin/Sublactam + Gentamicin or Tobramycin
  2. Vancomycin + Ceftriazone or Gentamicin/Tobramycin
25
Q

What drugs should you use to treat IE with penicillin allergy patients?

A
  1. Cephalosporins (3rd to 5th generation) or carbapenems

2. Vancomycin

26
Q

What is the most common cause of IE?

A

Staph. aureus

  • Majority of IE in drug abusers
  • Usually preceded by bacteremia
27
Q

What are two traits of Staph aureus?

A

Gram +, facultative anaerobe

28
Q

What are the virulence factors of Staph. aureus?

A
  1. Biofilm formation
  2. Capsule
  3. Adhesins
  4. Secreted enzymes
  5. Hemolysins
  6. Pathogenicity islands (contain info. for methacililn resistance)
29
Q

What is the most common infectious agent of the skin and surgical wounds? What can it cause?

A
  • Staph. aureus

- Impetigo, cellulitis, folliculitis, furuncles, carbuncles

30
Q

How does Staph aureus colonize the skin and evade host defenses?

A
  • Protein A (binds Fc portion of IgG)
  • Coagulase (forms fibrin coat around the organism)
  • Hemolysins and leukocidins (destroy RBCs and WBCs)
31
Q

Fact tree for Staph aureus?

A 
Bacteria
Gram + 
Cocci
Coagulase +
Catalase +
32
Q

What virulence factors does Staph. aureus have for deep tissue invasion?

A
  • Hyaluronidase (breaks down C.T.)
  • Staphylokinase (lyses formed clots)
  • Lipase (breaks down fat)
33
Q

What is the 2nd major cause of endocarditis?

A

Streptococcal species (viridian’s)

34
Q

What does Step Viridans infection usually involve?

A

Underlying mitral valve damage (rheumatic fever, etc.) which provides the site for bacterial colonization

35
Q

What is Strep. Viridan’s most important virulence factor?

A

-It can produce dextran for glycocalyx formation and surface adhesion proteins that assist colonization

36
Q

Fact tree for Strep. mutans?

A 
(viridans)
Gram + 
Cocci
Catalase -
Alpha-hemolytic
Bacitracin resistant
37
Q

What is the third major cause of IE?

A

Enterococcus species

38
Q

When do people usually get Enterococcus IE?

A

Genitourinary procedures in older men or obstetric procedures in younger women

39
Q

What is enterococci usually resistant to?

A

penicillins and carbepenems

40
Q

What are the virulence factors of Enterococci?

A

Pili
Surface proteins
Extracellular enzymes (like proteases and hyaluronidases)

41
Q

What different infections does Strep. pyogenes cause?

A

Impetigo, Erysipelas, Cellulitis, Toxic-shock syndrome, Necrotizing fasciitis

42
Q

Fact tree for Strep. pyogenes?

A 
Gram +
Cocci
Catalase -
Beta-hemolytic
Bacitracin sensitive
43
Q

What are important virulence factors for spread of Strep. pyogenes?

A
  1. Streptokinase (converts plasminogen to plasmin)
  2. M protein (resists phagocytosis)
  3. Hyaluronidase (breaks down connective tissue)
  4. DNase (digests DNA)
  5. Streptolysin O (destroys RBCs)
  6. Streptolysin S (destroys WBCs)
    - -Streptokinase and hyaluronidase are encoded by a lysogenized prophage
44
Q

What exotoxins does strep. progenies release in TSS and necrotizing fasciitis?

A

TSS - Exotoxin A (superantigen)

Nec. fasciitis - Exotoxin B (protease)

45
Q

What does RHD usually follow?

A

Strep. pyogenes pharyngitis in genetically predisposed individuals

46
Q

What is Rheumatic Heart Disease?

A

Type II hypersensitivity
-Damage to hear muscle and valves is attributed to autoantibodies (antibodies to bacterial antigens that cross-react with meromycin in the heart)

47
Q

What is a usual clinical indicator of RHD?

A

Mitral stenosis following pharyngitis with a rash

48
Q

What are three risks for RHD?

A
  1. Strep throat infection (prolonged/untreated)
  2. Prior case of rheumatic fever
  3. Age 5 to 15 yrs old
49
Q

What are the most common symptoms of RHD?

A
  • 2-4 wks after strep infection
  • Pain, swelling in large joints
  • Fever
  • Weakness
  • Muscle aches
  • SOB
  • Chest pain
  • Nausea and vomiting
  • Hacking cough
  • Circular rash
  • Lumps under the skin
50
Q

How do you treat rheumatic heart disease?

A
  • Penicillin Abx
  • Aspirin
  • Corticosteroids
  • Rest
51
Q

How do you prevent RHD?

A
  • Treat strep right away with Abx.

- Sore throat more than 24 hours = consult physician

52
Q

What is myocarditis? What organisms usually cause it?

A
  • Inflammation of the myocardium (middle layer of heart wall)
  • Usually viral (Cox B & Adenovirus (children))
  • Chest pain, heart failure, abnormal heart rhythms possible
53
Q

What are the traits of Coxsackievirus B?

A 
Virus
ssRNA (+)
Group IV
Nonsegmented
Icosahedral Nucleocapsid
Nonenveloped
Picornaviridae
Enterovirus
Coxsackievirus A & B
54
Q

What is pericarditis usually caused by ?

A

Acute infection

  • Viral infection (Coxsackievirus A & B, Echoviruses and Influenza)
  • Summer months
  • Chest pain associated with irritated layers of pericardium rubbing against each other
55
Q

What are typical RMSF symptoms?

A

Fever, headache, abdominal pain, vomiting, muscle pain, rash may develop but is often absent first few days, never develops in some patients

56
Q

What is used to teat RMSF? Where is it most prevalent?

A

Doxycyline

Lower midwest to the east coast

57
Q

What are the three hallmark signs of RMSF?

A

Rash, fever, headache

58
Q

How is RMSF transmitted?

A
  1. Carried in dogs/rodents
  2. Dermcentor wood or dog tick
  3. Infects endothelial cells
  4. Inflammation of endothelial lining of small blood vessels
  5. Maculopapular rash on palms and soles SPREADING TO THE TRUNK
  6. Widespread vasculitis –> headache –> CNS changes, renal damage –> may lead to death
59
Q

What are two obligate intracellular parasites that need ATP?

A

Chlamydiae & Rickettsiae

CRRAB Week 3 (12 decks)

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