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CVS Microbiology > Rheumatic Fever & Endocarditis > Flashcards

Rheumatic Fever & Endocarditis Flashcards

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Biology 101 flashcards
1
Q

Mention the name & basis of classification of streptococci in general & strept pyogenes specifically.

A

G: Lancefield classification, C carbohydrate antigen
P: Griffith classification, M protein antigen

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2
Q

Mention role of M protein

A

Antiphagocytic, binds to complement regulatory components, so bacterial surface is masked by host proteins.

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3
Q

Compare streptolysin O & S

A

O: oxygen labile, antigenic, increases beta hemolytic zone diameter
S: oxygen stable, non-antigenic, responsible for beta-hemolytic zone

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4
Q

Describe pathogenesis of rheumatic fever

A

Type II hypersensitivity to streptococcal M protein

Antibodies to M protein cross react with heart, joint & brain tissue causing carditis, migratory polyarthritis & chorea.

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5
Q

ASO titer is more elevated in ….. infection

A

Pharyngeal

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6
Q

Mention type of sera which prove recent strept infection

A

Acute & convalescent sera

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7
Q

Describe prophylaxis of rheumatic fever

A

Long acting penicillin, erythromycin

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8
Q

Mention risk factors for infective endocarditis

A
  • Unsafe intravenous injection (indwelling catheter, iv drug user)
  • Dental invasive procedures
  • Colorectal cancer
  • Heart valve disease (congenital, rheumatic fever)
  • Prosthetic heart valve, pacemaker, defibrillator)
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9
Q

Adhesion of bacteria is enhanced by their ….., combination of organism & thrombus forms ….., symtoms of ….. develop with valve destruction. It can eventually lead to ……

A

Glycocalyx, vegetation, regurgitation, cerebrovascular accidents

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10
Q

Describe clinical manifestations of infective endocarditis

A

Constituational symptoms
Symptoms due to spread of emboli, Janeway lesions
Symptoms of heart valve destruction, heart murmurs & heart failure
Symptoms due to antigen-antibody complex deposition, Osler’s nodes, arthritis, glomeruloneohritis (haematuria)

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11
Q

Describe classification of infective endocarditis

A

Native/prosthetic valve is main classification
Then according to source (exogenous/endogenous) (community/hospital-acquired)
Or to severity (acute/subacute)

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12
Q

Mention types of infective endocarditis caused by 1. viridans streptococci 2. Staph epidermidis

A
  1. Community acqured native valve & late prosthetic valve

2. Hospital acquired & iv drug user native valve & prosthetic valve (both)

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13
Q

Mention most common causative agents of acute endocarditis

A
  1. S.aureus
  2. S.epidermidis
  3. Enterococcus species
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14
Q

How does infection reach heart valves?

A
  • colonization of indwelling venous catheter
  • repeated unsafe iv injection
  • colorectal cancers
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15
Q

Subacute endocarditis occurs after …..

A

Tonsillectomy or tooth extraction

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16
Q

Mention Diagnosis of infective endocarditis methods

A
  1. Positive blood culture (three blood cultures should be obtained over at least one hour.
  2. Echocardiographic finding
  3. Clinical criteria (modified Duke criteria)
17
Q

S.aureus ferments … salt

A

Mannitol

18
Q

Mention cell-associated virulence factors of S.aureus

A
  1. Protein A, binds Fc potion of Abs
  2. Bound coagulase
  3. Polysaccharide antiphagocytic capsule
19
Q

Mention enzyme virulence factors of S.aureus

A

Coagulase & beta-lactamase

20
Q

Mention toxin virulence factors of S.aureus

A

P-V leukocidin , alpha toxin (hemolytic)

21
Q

S.epidermidis is sensitive to …… .

A

Novobiocin

22
Q

Describe pathogenesis of S.epidermidis endocarditis

A

It is normal cutaneous flora, can colonize iv catheters, prosthetic devices, shunt by its glycocalyx which allows its adherence.

23
Q

Mention microbiological identification criteria of Enterococcus

A

Gram +ve cocci arranged in diploes, resistant to bile & salt, catalase -ve, group D streptococcal cell wall carbohydrate antigen.

24
Q

Describe enterococcus antibiotic resistance

A

High pattern of resistance
Naturally resistant resistant to penicillin, cephalosporins, aminoglycosides, lincosamides.
VRE are present treated by combination of linezolid & two streptogramin (Quinupristin-dalfopristin)

25
Q

Epidemiology of Enterococcus

A

Natural habitat is human intestine, they may cause disease outside GIT esp in hospitalized or immunocomp. individuals

26
Q

Viridans strep are resistant to ……

A

Optochin & bile

27
Q

Mention empiric treatment if infective endocarditis

A

Vancomycin + ceftriaxone/gentamycin

28
Q

Describe prophylaxis of SABE

A

By amoxicillin before dental procedures & surgery involving resp mucosa
In perons with previous endocarditis, prosthetic heart valves, centain tyoes of CHD

CVS Microbiology (1 decks)

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