Infective endocarditis resident survival guide

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Farman Khan, MD, MRCP [2]; Mohamed Moubarak, M.D. [3]; Rim Halaby, M.D. [4]

Infective endocarditis Resident Survival Guide Microchapters


Infective endocarditis is an infection in the endothelium of the heart, including but not limited to the valves. While acute bacterial endocarditis is caused by an infection with a virulent organism such as staphylococcus aureus, group A or other beta-hemolytic streptococci, subacute bacterial endocarditis is an indolent infection with less virulent organisms like streptococcus viridans. Patients with unexplained fever for more than 48 hours and who are at high risk for infective endocarditis and patients among whom valve regurgitation is newly diagnosed should undergo a diagnostic workup to rule out endocarditis. The diagnosis of endocarditis depends on a thorough history and physical exam as well as the results of blood cultures and the findings on transthoracic echocardiogram or transesophageal echocardiogram. The modified Duke criteria is used to establish the diagnosis of endocarditis. Endocarditis is initially treated with empiric antibiotic therapy until the causative agent is identified.[1][2]


Life Threatening Causes

Acute endocarditis is a life-threatening condition and must be treated as such irrespective of the underlying cause.

Common Causes

FIRE: Focused Initial Rapid Evaluation

A Focused Initial Rapid Evaluation (FIRE) should be performed to identify patients in need of immediate intervention.[1][3]

Boxes in salmon color signify that an urgent management is needed.

Abbreviations: CT: Computed tomography ; CTA: Computed tomography angiography; MRA: Magnetic resonance angiography; MRI: Magnetic resonance imaging; TEE: Transesophageal echocardiography; TTE: Transthoracic echocardiography

Identify cardinal signs and symptoms that increase the pretest probability of endocarditis

❑ Persistent fever
❑ New valvular regurgitation murmur
Janeway lesion
Osler's node
Roth's spots
❑ New AV block
❑ High risk factors

❑ Pre-existing cardiac abnormality
Prosthetic valve
❑ Recent surgical or medical procedures
❑ Intravenous drug use
❑ Recent bacterial infection
❑ History of previous endocarditis
❑ Order blood cultures (at least 2 sets)
❑ Order TTE, or

❑ Order a TEE if one or more of the following is present

❑ Non diagnostic TTE in a suspected infective endocarditis
❑ Clinical complications
Intracardiac device leads
Staphylococcus aureus bacteremia without a known cause
Prosthetic valve with persistent fever without bacteremia
Prosthetic valve with a new murmur
❑ Nosocomial Staphylococcus aureus bacteremia with known extra-cardiac port of entry

❑ Evaluate the modified Duke criteria
Does the patient have any findings suggestive of complications of endocarditis that require urgent intervention?
Yes, the patient has cardiac complications
Yes, the patient has extra cardiac complications
No, the patient does not have any complications
❑ Decreased ejection fraction
Severe valvular insufficiency
❑ Valvular abscess
❑ Valvular dehiscence
❑ Valvular rupture
❑ Valvular fistula
❑ Periannular extension of the infection
Focal neurological deficits
Facial droop
Unilateral hemiparesis
Altered mental status
❑ Tender pulsatile mass
Hematemesis, hemobilia, jaundice (suggestive of involvement of the hepatic artery)
Hematuria (suggestive of involvement of the renal artery)
❑ Massive bloody diarrhea (suggestive of involvement of a bowel artery)
❑ Order non contrast head CT scan
❑ Order MRA or CTA
❑ Order abdominal CT scan or MRI
Embolism to the brain
❑ Evaluate medical vs surgical intervention
❑ Consider surgical ligation of the involved artery

Complete Diagnostic Approach

A complete diagnostic approach should be carried out after a focused initial rapid evaluation is conducted and following initiation of any urgent intervention.[1][2]

Abbreviations: TEE: Transesophageal echocardiography; TTE: Transthoracic echocardiography

Characterize the symptoms:

❑ Onset of the symptoms

❑ Acute
❑ Subacute

Pleuritic chest pain
Back pain
Shortness of breath
Productive cough
Flank pain (suggestive of septic emboli or glomerulonephritis)
Hematuria (suggestive of septic emboli or glomerulonephritis)
Seizures (suggestive of septic emboli)
❑ Focal neurological deficits due to stroke (suggestive of septic emboli) or mycotic aneurysm
❑ Reversible focal neurological deficits due to transient ischemic attack (suggestive of septic emboli)

Identify existing risk factors for endocarditis:

❑ History of rheumatic heart disease
Prosthetic valves
Intravenous drug use

❑ Adulterants used in the mixture, such as talc which increases the vulnerability of the valve to infection[4]
❑ Sharing the equipment
❑ Use of cotton filters (associated with cotton fever)[5]
❑ The process of cleaning the equipment

❑ Previous infective endocarditis
Cardiac transplantation with valvular abnormality
Congenital heart diseases with a shunt
Acquired heart diseases
❑ Medical procedures
❑ Surgical procedures
❑ Indwelling prosthetic devices
❑ Bleeding during toothbrushing
❑ Recent dental procedure

Examine the patient:



Blood pressure

❑ Wide pulse pressure (suggestive of aortic insufficiency)
❑ Narrow pulse pressure (suggestive of left ventricular failure)


Splinter hemorrhages
Osler's nodes
Janeway lesions

Oral examination
❑ Poor oral hygiene[6]
Teeth looking for periodontitis, plaque and calculus[6]
Gingiva looking for gingivitis[6]
❑ Recent dental procedure


Conjunctival hemorrhage
Roth's spots in the retina

Cardiovascular examination

Heart murmur: New or change in the character of a previous murmur

Aortic insufficiency (early diastolic, decrescendo, best heard in the left sternal border)
Tricuspid regurgitation (holosystolic, best heard over the fourth intercostal area at left sternal border)
Mitral regurgitation (holosystolic, best heard at the apex)

Respiratory examination

Rales (suggestive of heart failure)

Abdominal examination

Reduced bowel sounds (suggestive of mesenteric embolization or ileus)
Abdominal pain

Flank pain (suggestive of embolus to the kidney)
Left upper quadrant pain (suggestive of splenic infarct)



Janeway lesions (painless hemorrhagic cutaneous lesions on the palms and soles)
Gangrene of fingers
Splinter hemorrhages
Osler's nodes (painful subcutaneous lesions in the distal fingers)

Neurological examination

❑ Full neurological exam

❑ Focal deficits (suggestive of stroke or brain abscess)
Order tests:

Blood culture (at least two sets)
❑ Order a TTE
❑ Order a TEE if one or more of the following is present

❑ Non diagnostic TTE in a suspected infective endocarditis (Class I, level of evidence B)
❑ Clinical complications (Class I, level of evidence B)
Intracardiac device leads (Class I, level of evidence B)
Staphylococcus aureus bacteremia without a known cause (Class IIa, level of evidence B)
Prosthetic valve with persistent fever without bacteremia (Class IIa, level of evidence B)
Prosthetic valve with a new murmur (Class IIa, level of evidence B)
❑ Nosocomial Staphylococcus aureus bacteremia with known extra-cardiac port of entry (Class IIb, level of evidence B)
Evaluate the Modified Duke Criteria for infective endocarditis:[7]
Probability of infective endocaritis Characteristics
Definite diagnosis by pathological criteria❑ Microorganisms demonstrated by culture or histological examination
of a vegetation, OR
❑ Pathological lesions; vegetation or intracardiac abscess confirmed by histological
examination showing active endocarditis
Definite diagnosis by clinical criteria❑ 2 major criteria, OR

❑ 1 major criterion and 3 minor criteria, OR

❑ 5 minor criteria
Possible diagnosis❑ 1 major criterion and 1 minor criterion, OR
❑ 3 minor criteria
Rejected diagnosis❑ Firm alternative diagnosis explaining evidence of infective endocarditis, OR

❑ Resolution of infective endocarditis with antibiotic therapy for 4 days, OR
❑ No pathological evidence of infective endocarditis at surgery or autopsy, with antibiotic therapy for 4 days, OR

❑ Does not meet criteria for possible infective endocarditis as above
Consider alternative diagnoses:

❑ Culture negative endocarditis

❑ Previous treatment with antibiotics
❑ Fastidious bacterial infection
Fungal infection
❑ Inappropriate blood culture technique

Marantic endocarditis

❑ Valvular vegetations
❑ Negative blood culture
❑ Hypercoagulable state, lupus or antiphospholipid syndrome

Cellulitis (skin inflammatory skin)
Catheter related infection (presence of catheter associated with associated local erythema and tenderness)
Cardiac device infection
Prosthetic joint infection (localized inflammatory signs)
Fever of unknown origin

Cotton fever[5]


Shown below is an algorithm depicting the management of infective endocarditis.[1][2]

Abbreviations: TEE: Transesophageal echocardiography; TTE: Transthoracic echocardiography

Once the diagnosis of infective endocarditis is confirmed, initiate the treatment:

❑ Begin antibiotic treatment
❑ Order blood cultures every 24-48 hours until no bacteremia can be detected
❑ Temporarily discontinue anticoagulation if one of the following is present

❑ Signs and symptoms of CNS involvement consistent with embolism or stroke (Class IIa, level of evidence B)
Vitamin K antagonist administration (Class IIb, level of evidence B)

❑ Remove the pacemaker of the defibrillator system if one of the following is present

❑ Documented infection of the device or leads (Class I, level of evidence B)
❑ Valvular infective endocarditis by Staphylococcus aureus or fungi in the absence of documented infection of the device or leads (Class IIa, level of evidence B)
❑ Patient scheduled for valve surgery (Class IIa, level of evidence C)
❑ Persistent vegetations and recurrent emboli despite the antibiotic regimen (Class IIa, level of evidence B)

❑ Manage the patient with a multidisciplinary team

❑ Consult an infectious disease specialist
❑ Consult a cardiologist
❑ Consult a cardiac surgeon
Does the patient have any of the following conditions that require an early valve replacement surgery during hospitalization?

Heart failure due to the valve dysfunction (Class I, level of evidence B)
❑ Left sided infective endocarditis due to staphylococcus aureus, fungal or highly resistant organisms (Class I, level of evidence B)
Heart block, annular or aortic abscess or destructive lesions (Class I, level of evidence B)
❑ Persistent bacteremia or fever 5 to 7 following the initiation of the antibiotics (Class I, level of evidence B)
❑ Relapse of the infection depsite a complete course of antibiotics in prosthetic valve endocarditis when no portal of infection can be identified (Class I, level of evidence C)
❑ Recurrent emboli and persistent vegetations despite antibiotic therapy (Class IIa, level of evidence B)
❑ Mobile vegetations with a length more than 10 mm in native valve endocarditis(Class IIb, level of evidence B)

❑ Schedule for early surgery
Follow up the patient:

❑ Repeat TTE before discharge
❑ Refer for cessation of drug abuse (if applicable)
❑ Educate the patient about the signs and symptoms of infective endocarditis
❑ Recommend a thorough dental examination
❑ Monitor for complications

❑ Relapse (fever, chills)
❑ New or worsening heart failure
Antibiotic toxicity
❑ Vestibular toxicity
Diarrhea or colitis
Reevaluate the patient with TTE and/or TEE if one of the following is present:

❑ Change in clinical signs and symptoms

❑ New murmur
❑ Persistent fever
Heart failure
Atrioventricular heart block

❑ High risk of complications

❑ Large vegetations on echocardiogram
Staphylococcus, enterecoccal, or fungal infections

Antibiotic Regimens

A complete list of pathogen specific antibiotics regimens with appropriate dosages and duration of treatment is available here.

Modified Duke Criteria

Shown below is a table summarizing the major and minor Modified Duke Criteria.[7]

Modified Duke Criteria
Major criteria Minor criteria
1- Positive Blood Culture for Infective Endocarditis

❑ Typical microorganism consistent with infective endocarditis from 2 separate blood cultures, in the absence of a primary focus:

Viridans streptococci, streptococcus bovis
HACEK group
❑ Community-acquired staphylococcus aureus


❑ Microorganisms consistent with infective endocarditis from persistently positive blood cultures defined as:

❑ At least 2 positive cultures of blood samples drawn >12 hours apart, or
❑ All of 3 or a majority of 4 separate cultures of blood (with first and last sample drawn 1 hour apart)


❑ Single positive blood culture for Coxiella burnetii or anti–phase 1 IgG antibody titer >1:800

2-Echocardiographic evidence of endocardial involvement
❑ Oscillating intracardiac mass on valve or supporting structures, in the path of regurgitant jets, or on implanted material in the absence of an alternative anatomic explanation, or
Abscess, or
❑ New partial dehiscence of prosthetic valve, or
❑ New valvular regurgitation

1- Predisposition

❑ Predisposing heart condition or intravenous drug use

2- Fever
❑ Temperature > 38.0° C (100.4° F)

3- Vascular phenomena
Major arterial emboli
❑ Septic pulmonary infarcts
Mycotic aneurysm
Intracranial hemorrhage
Conjunctival hemorrhage
Janeway lesions

4- Immunologic phenomena
Osler's nodes
Roth spots
Rheumatoid factor

5- Microbiological evidence
❑ Positive blood culture but does not meet a major criterion as noted above


❑ Serological evidence of active infection with organism consistent with infectious endocarditis


  • If HACEK bacteremia is detected without any focus of infection, suspect the presence of infective endocarditis even in the absence of the typical signs and symptoms.[2]


  • Do not administer infective endocarditis prophylaxis for the following dental procedures:
    • Anesthetic injections in noninfected tissue
    • Dental radiographs
    • Shedding of deciduous teeth
    • Placement of orthodontic brackets
    • Placement or removal of prosthodontic or orthodontic appliances
    • Adjustment of orthodontic appliances
    • Bleeding following trauma to the oral mucosa or lips[8]


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 "2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease: Executive Summary". Retrieved 4 March 2014.
  2. 2.0 2.1 2.2 2.3 2.4 Baddour, LM.; Wilson, WR.; Bayer, AS.; Fowler, VG.; Bolger, AF.; Levison, ME.; Ferrieri, P.; Gerber, MA.; Tani, LY. (2005). "Infective endocarditis: diagnosis, antimicrobial therapy, and management of complications: a statement for healthcare professionals from the Committee on Rheumatic Fever, Endocarditis, and Kawasaki Disease, Council on Cardiovascular Disease in the Young, and the Councils on Clinical Cardiology, Stroke, and Cardiovascular Surgery and Anesthesia, American Heart Association: endorsed by the Infectious Diseases Society of America". Circulation. 111 (23): e394–434. doi:10.1161/CIRCULATIONAHA.105.165564. PMID 15956145. Unknown parameter |month= ignored (help)
  3. 3.0 3.1 Weinstein L (1986). "Life-threatening complications of infective endocarditis and their management". Arch Intern Med. 146 (5): 953–7. PMID 3516105.
  4. Frontera JA, Gradon JD (2000). "Right-side endocarditis in injection drug users: review of proposed mechanisms of pathogenesis". Clin Infect Dis. 30 (2): 374–9. doi:10.1086/313664. PMID 10671344.
  5. 5.0 5.1 Harrison DW, Walls RM (1990). ""Cotton fever": a benign febrile syndrome in intravenous drug abusers". J Emerg Med. 8 (2): 135–9. PMID 2362114.
  6. 6.0 6.1 6.2 Lockhart PB, Brennan MT, Thornhill M, Michalowicz BS, Noll J, Bahrani-Mougeot FK; et al. (2009). "Poor oral hygiene as a risk factor for infective endocarditis-related bacteremia". J Am Dent Assoc. 140 (10): 1238–44. PMC 2770162. PMID 19797553.
  7. 7.0 7.1 Li JS, Sexton DJ, Mick N, Nettles R, Fowler VG, Ryan T; et al. (2000). "Proposed modifications to the Duke criteria for the diagnosis of infective endocarditis". Clin Infect Dis. 30 (4): 633–8. doi:10.1086/313753. PMID 10770721.
  8. 8.0 8.1 Bonow RO, Carabello BA, Chatterjee K; et al. (2008). "2008 Focused update incorporated into the ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 1998 Guidelines for the Management of Patients With Valvular Heart Disease): endorsed by the Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons". Circulation. 118 (15): e523–661. doi:10.1161/CIRCULATIONAHA.108.190748. PMID 18820172. Unknown parameter |month= ignored (help)

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