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HMS Homeostasis I > Infective Endocarditis > Flashcards

Infective Endocarditis Flashcards

1
Q
A

Vegetations on the mitral valve caused by endocarditis

Mesh of platelets, fibrin, microorganisms, and inflammatory cells

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2
Q

Acute endocarditis

A

Hectically febrile illness that rapidly damages cardiac structures, seeds extracardiac sites, and, if untreated, progresses to death within weeks

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3
Q

Subacute endocarditis

A

Follows an indolent course; causes structural cardiac damage only slowly, if at all; rarely metastasizes; and is gradually progressive unless complicated by a major embolic event or a ruptured mycotic aneurysm

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4
Q

Risk factors for endocarditis

A
  • Congenital heart disease
  • Intracardiac devices
  • Rheumatic heart disease
  • IV drug use
  • Degenerative valve disease
  • Advanced age
  • Hemodialysis
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5
Q

Risk of infective endocarditis following valve replacement

A

The risk of PVE is greatest during the first 6–12 months after valve replacement; gradually declines to a low, stable rate thereafter; and is similar for mechanical and bioprosthetic devices.

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6
Q

Common bacteria involved in infective endocarditis

A

Note that many bacteria can cause IE, but these are the most prevalent:

  • Staphylococcus aureus
  • Coagulase-negative Staphylococci
  • Enterococci
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7
Q

Primary entry for streptococci

A

Oral tract

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8
Q

Primary entry for staphylococci

A

Skin

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9
Q

Primary entry for HACEK organisms

A

Upper respiratory tract

Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae

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10
Q

Streptococcus gallolyticus subspecies gallolyticus (formerly S. bovis biotype 1)

A

Originates from the gastrointestinal tract, where it is associated with polyps and colonic tumors, and enterococci enter the bloodstream primarily from the genitourinary tract.

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11
Q

Nosocomial

A

(of a disease) originating in a hospital.

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12
Q

68–85% of CoNS strains that cause PVE are resistant to ___.

A

68–85% of CoNS strains that cause PVE are resistant to methicillin.

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13
Q

___ is contraindicated for most cases of infective endocarditis

A

Methicillin is contraindicated for most cases of infective endocarditis

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14
Q

How species of pathogen differs in IV drug use-induced IE

A

In addition to more frequent causes, Pseudomonas aeruginosa and Candida species often affect these individuals.

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15
Q

Marantic endocarditis

A

Uninfected vegetations seen in patients with malignancy and chronic diseases, specifically those resulting in a hypercoagulable state.

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16
Q

Nonbacterial thrombotic endocarditis

A

Undamaged endothelium is quite resistant to infection in most individuals. However, if the endothelium is damaged, a platelet-fibrin clott may develop, and this site is susceptible to infection. During transient bacteremia, these thrombi may serve as a nucleation site.

Often in these individuals there is pre-existing structural heart disease predisposing to endothelial injury, such as mitral regurgitation, aortic stenosis, aortic regurgitation, ventricular septal defects.

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17
Q

The organisms that commonly cause endocarditis have . . .

A

The organisms that commonly cause endocarditis have surface adhesin molecules, collectively called microbial surface components recognizing adhesin matrix molecules (MSCRAMMs), that mediate adherence to NBTE sites or injured endothelium.

18
Q

Clinical manifestations of endocarditis

A
  • Fever
  • Chills
  • Night sweat
  • Weight loss
  • Embolization of vegetation fragments and downstream effects (infection or infarction or remote tissues)
  • Type III hypersensitivity reactions
19
Q

The diagnosis of infective endocarditis is established with certainty only when . . .

A

The diagnosis of infective endocarditis is established with certainty only when vegetations are examined histologically and microbiologically.

20
Q

Modified Duke criteria

A
  • Designed to provide a good guess of whether or not someone has IE
  • 2 major, 1 major + 3 minor, or 5 minor establish presumptive diagnosis if no other explanation is available
  • Major: 1) positive blood culture + confirmation, 2) evidence of endocardial involvement
  • Minor: 1) Predisposing heart condition OR IV drug use, 2) Fever, 3) Vascular phenomena (evidence of embolism), 4) Evidence of type III hypersensitivity, 5) Microbiologic evidence other than positive blood culture
21
Q

Pending culture results, empirical antimicrobial therapy should . . .

A

Pending culture results, empirical antimicrobial therapy should be withheld initially from hemodynamically stable patients with suspected subacute endocarditis, especially those who have received antibiotics within the preceding 2 weeks

The delay allows blood for additional cultures to be obtained without the confounding effect of empirical treatment.

22
Q

Patients with acute endocarditis or with deteriorating hemodynamics who may require urgent surgery should receive. . .

A

Patients with acute endocarditis or with deteriorating hemodynamics who may require urgent surgery should receive empirical treatment immediately after three sets of blood cultures are obtained over several hours.

23
Q

Utility of serological testing in infective endocarditis

A

Serologic tests can be used to implicate organisms that are difficult to recover by blood culture: Brucella, Bartonella, Legionella, Chlamydia psittaci, and C. burnetii.

24
Q

Transthoracic echocardiography in infective endocarditis

A

Noninvasive and exceptionally specific; however, it cannot image vegetations <2 mm in diameter, and in 20% of patients the images are inadequate. TTE detects vegetations in 65–80% of patients with definite clinical endocarditis but is not optimal for evaluating prosthetic valves or detecting intracardiac complications.

Safe and detects vegetations in >90% of patients with definite endocarditis, but still a ~10% false negative rate.

25
Q

Because S. aureus bacteremia is associated with a high prevalence of endocarditis, . . .

A

Because S. aureus bacteremia is associated with a high prevalence of endocarditis, routine echocardiographic evaluation (TTE or preferably TEE) is recommended in these patients.

26
Q

Other labs commonly increased in endocarditis

A
  • ESR
  • CRP
  • Rheumatoid factor
  • Circulating immune complex titer
27
Q

Prevention of endocarditis

A
  • Suprisingly, the evidence for effectiveness of antibiotic prophylaxis is not great, so as of right now it is just recommended for the very highest risk patients
  • Maintaining good dental hygiene in at-risk patients is essential and a recommended goal
  • There is evidence of effective antibiotic prophylaxis specifically in patients undergoing dental and periodontal operations, as well as respiratory tract surgery
28
Q

“Sticky” bugs

A

Staphylococcus aureus, but not as much CoNSA

Pseudomonas aeruginosa, but less so Gram negative enterococci

29
Q

Virulence and clinical bacteremia

A

Less virulent bugs can be disseminated and you can just go along without many symptoms. Not uncommonly people have enterococcal bacteremia or streptococcal bacteremia for months before presenting to the hospital. But if you have staphylococcal or streptococcal bacteremia, you will go to the hospital immediately.

More virulent = more acute

Less virulent = more likely subacute

30
Q

Valvular lesions and antibiotic prophylaxis

A

Valvular lesions do not indicate prophylaxis on their own, unless there is already good evidence of past history and susceptibility.

31
Q

Streps that cause endocarditis

A

Not so much beta hemolytics (the ones that cause strep throat)

Mostly alpha hemolytics (strep viridans)

32
Q

Major bowel flora in endocarditis

A

Strep bovis = strep gadolyticus

Enterococcus

33
Q

Aortic valve endocarditis and heart block

A

If the infection erodes through the annulus to the paravalvar region, it may form an abscess and interact with the conduction system. This appears first as 1st degree heart block, but may progress to 3rd degree.

If 1st degree heart block develops on ECG and the patient is not responding well to antiboitics (unlikely given poor antibiotic penetration), this is an indication for surgery. This is a very complicated scenario given that you are operating on an infected organ, but

34
Q

Schema of complications in infective endocarditis

A
35
Q

Most commonly affected valve in IV drug users

A

Tricuspid valve

36
Q

Features of tricuspid endocarditis

A
  • No embolisms systemically
  • Possible pulmonary embolisms
    • May lead to pulmonary abscess
  • Can still find type III hypersensitivity lesions
    • Osler nodes
    • Roth spots
    • Glomerulonephritis
  • Splenomegaly
  • Myocardial abscess
37
Q

What is this skin finding?

A

An Osler’s node. Result of type III hypersensitivity reaction within the skin. You can tell by the border that it is inflammed, unlike lesions caused by emboli.

Note that on exam, these will be painful while Janeway’s lesions will be painless

38
Q

What is this skin finding?

A

Janeway’s lesion

Result of endocardital embolism

39
Q

What is this retinal finding?

A

Roth spots

Result of type III hypersensitivity-induced coagulation in the retina

40
Q

What is this nail finding?

A

Splinter hemorrhage

Nail finding indicative of embolic manifestations of endocarditis

HMS Homeostasis I (62 decks)

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