Infective endocarditis resident survival guide

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]

Definition

Infection of the endothelium of the heart including but not limited to the valves. It can be either acute or subacute. Acute bacterial endocarditis is defined as Infection of normal heart valves with a virulent organism like S. aureus, Group A or other beta-hemolytic streptococci, Streptococcus pneumoniae. Subacute bacterial endocarditis is an indolent infection of abnormal valves with less virulent organism like Streptococcus viridans.

Criteria	Definite Infective Endocarditis According to Modified Duke Criteria
Pathological Criteria	Microorganisms demonstrated by culture or histological examination of a vegetation Pathological lesions; vegetation or intracardiac abscess confirmed by histological examination showing active endocarditis
Clinical Criteria	2 major criteria; or 1 major criterion and 3 minor criteria; or 5 minor criteria
Possible IE	1 major criterion and 1 minor criterion; or 3 minor criteria
Rejected	Firm alternative diagnosis explaining evidence of IE; or Resolution of IE syndrome with antibiotic therapy for 4 days; or No pathological evidence of IE at surgery or autopsy, with antibiotic therapy for 4 days; or Does not meet criteria for possible IE as above

Causes

Life Threatening Causes

Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. Endocarditis can be a life-threatening condition if it is left untreated, and it must be treated as such irrespective of the causes.

Common Causes

• Streptococcus viridans
• Staphylococci
• Enterococcus.

Management

Diagnostic Criteria

Shown below is an algorithm depicting the diagnostic criteria of infective endocarditis based on the 2005 American Heart Association (AHA) technical review and medical position statement regarding guidelines on infective endocarditis.

Duke Criteria

The Duke Clinical Criteria for Infective Endocarditis requires either: ❑ Two major criteria, or ❑ One major and three minor criteria, or ❑ Five minor criteria

Major Criteria

Minor criteria

Positive Blood Culture for Infective Endocarditis Typical microorganism consistent with infective endocarditis from 2 separate blood cultures, as noted below: ❑ Viridans streptococci, streptococcus bovis ❑ HACEK group ❑ Community-acquired staphylococcus aureus ❑Enterococci, in the absence of a primary focus, or Microorganisms consistent with infective endocarditis from persistently positive blood cultures defined as: ❑ 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) 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 (worsening or changing of preexisting murmur not sufficient)

Predisposition: ❑ Predisposing heart condition or intravenous drug use Fever: ❑ Temperature > 38.0° C (100.4° F) Vascular phenomena: ❑ Major arterial emboli ❑ Septic pulmonary infarcts ❑ Mycotic aneurysm ❑ Intracranial hemorrhage ❑ Conjunctival hemorrhage ❑ Janeway lesions Immunologic phenomena: ❑ Glomerulonephritis ❑ Osler's nodes ❑ Roth spots ❑ Rheumatoid factor 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 Echocardiographic findings: ❑ Consistent with infectious endocarditis but do not meet a major criterion as noted above

Diagnostic approach

Shown below is an algorithm summarizing the approach to infective endocarditis.

Vital signs
❑ Temperature

❑ Fever

❑ Blood pressure

❑ Wide pulse pressure (sign of aortic insufficiency)

❑ Narrow pulse pressure (sign of left ventricular failure)

Skin

❑ Petechiae
❑ Splinter hemorrhages
❑ Osler's nodes
❑ Janeway lesions

Eyes

❑ Conjunctival hemorrhage
❑ Roth's spots in the retina

Heart

❑ Heart murmur

❑ Aortic insufficiency

❑ Tricuspid regurgitation

❑ Mitral regurgitation

Lungs

❑ Rales as a sign of heart failure

Abdomen

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

❑ Flank pain (sign of embolus to the kidney)

❑ Left upper quadrant pain (sign of splenic infarct)

❑ Splenomegaly

Extremities

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

Neurologic

❑ Full neurological exam

❑ Focal deficits (suggestive of stroke or brain abscess)}}

Characterize the symptoms ❑ Onset of the symptoms: ❑ Acute ❑ Subacute ❑ Fever ❑ Chills ❑ Rigors ❑ Sweats ❑ Weakness ❑ Myalgias ❑ Arthralgias ❑ Anorexia ❑ Fatigue ❑ Shortness of breath ❑ Hemoptysis ❑ Sputum ❑ Cough ❑ Pleuritic chest pain ❑ Seizures ❑ Symptoms suggestive of stroke ❑ Symptoms suggestive of transient ischemic attack

Identify existing risk factors:

Examine the patient:

Order laboratory tests: ❑ Blood culture ❑ WBC ❑ Marked leukocytosis is present ❑ Erythrocyte sedimentation rate ❑ Markedly elevated ❑ Rheumatoid factor ❑ A positive serum rheumatoid factor in 50% of patients with subacute disease ❑ BUN ❑ Cr ❑ Urinalysis

Order imaging studies: ❑ EKG ❑ Echocardiography ❑ CT scan of the head ❑ MRI brain

Therapeutic Approach

Shown below an algorithm depicting the general therapeutic approaches of infective endocarditis based on the 2005 American Heart Association (AHA) technical review and medical position statement regarding guidelines on infective endocarditis.

Evaluate the patient

Acute or hemodynamically unstable patient

Subacute hemodynamically stable patient

Stabilize the patient

Wait for blood culture results

Don`t wait for blood culture results and start empirical antibiotic therapy

Start antibiotic therapy according to the detected pathogen

Streptococci antibiotic regimen

Enterococci antibiotic regimen

Staphylococci antibiotic regimen

HACEK Organisms antibiotic regimen

Culture negative antibiotic regimen

Prophylactic Approach

Identify the high risk patients ❑ Prosthetic valves patients ❑ Previous infective endocarditis ❑ Cardiac transplant recipients with valves abnormality ❑ Congenital heart diseases ❑ Unrepaired cyanotic ❑ Completely repaired defect with prosthetic material or device ❑ Repaired with residual defects at the site or adjacent to the site of a prosthetic material

References

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