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]; Rim Halaby, M.D. [4]

Synonyms and keywords: IE

Definition

Infective endocarditis is the infection of 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.

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

• Enterococcus
• Staphylococcus aureus
• Streptococcus viridans

Management

Shown below is an algorithm depicting the management of infective endocarditis.

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: ❑ History of rheumatic heart disease ❑ Prosthetic valves ❑ Intravenous drug use ❑ Previous infective endocarditis ❑ Cardiac transplantation with valvular abnormality ❑ Congenital heart diseases ❑ Acquired heart diseases ❑ Immunodeficiency

Examine the patient: 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 Dental examination ❑ Teeth ❑ Gingiva 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 hemorrhages ❑ Osler's nodes (painful subcutaneous lesions in the distal fingers) Neurologic ❑ Full neurological exam ❑ Focal deficits (suggestive of stroke or brain abscess)

If the patient has any of the following proceed with tests: ❑ Unexplained fever for more than 48 hours and high risk for infective endocarditis, OR ❑ Newly diagnosed valve regurgitation

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: 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 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

Once the diagnosis of infective endocarditis is confirmed, initiate the treatment: ❑ Begin antibiotic treatment ❑ Order blood cultures very 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) ❑ Schedule early surgery during hospitalization before completion of the antibiotics course if one of the following is present ❑ 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) ❑ 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

Follow up the patient: ❑ Repeat TTE ❑ Refer for cessation of 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 ❑ Embolism ❑ Persistent fever ❑ Heart failure ❑ Abscess ❑ Atrioventricular heart block ❑ High risk of complications ❑ Large vegetations on echocardiogram ❑ Staphylococcus, enterecoccal, or fungal infections

TEE: Transesophageal echocardiocardiography; TTE: Transthoracic echocardiocardiography

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.

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 ❑ Enterococci OR ❑ 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) OR ❑ 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 ❑ Glomerulonephritis ❑ Osler's nodes ❑ Roth spots ❑ Rheumatoid factor 5- Microbiological evidence ❑ Positive blood culture but does not meet a major criterion as noted above OR ❑ Serological evidence of active infection with organism consistent with infectious endocarditis

Prophylaxis

Shown below is an algorithm depicting the general prophylactic approaches of infective endocarditis.

Identify high risk patients: (Class IIa, Level of evidence B) ❑ Prosthetic valves patients ❑ Previous infective endocarditis ❑ Cardiac transplant recipients with valves regurgitation due to structurally abnormal valve ❑ Congenital heart diseases ❑ Unrepaired cyanotic congenital heart diseases ❑ Completely repaired defect with prosthetic material or device ❑ Repaired with residual defects
Identify high risk procedures: ❑ Dental procedures ❑ Manipulation of gingival tissue, or ❑ Manipulation of the periapical region of teeth, or ❑ Perforation of the oral mucosa ❑ Respiratory tract procedures involving incision of the respiratory tract mucosa ❑ Tonsillectomy ❑ Adenoidectomy ❑ Gastrointestinal (GI) and genitourinary (GU) procedures only if GI or GU tract infection is present
❑ Administer prophylaxis

Antibiotic Prophylaxis

Shown below is a table depicting the prophylaxis antibiotic regimes for infective endocarditis.

Infective Endocarditis Antibiotic Prophylaxis Oral treatment is tolerated Not allergic to penicillin Allergic to penicillin ▸ Amoxicillin 2 g ▸ Ampicillin 2 g IM or IV OR ▸ Cefazolin 1 g IM or IV OR ▸ Ceftriaxone 1 g IM or IV Oral treatment is not tolerated Not allergic to penicillin Allergic to penicillin ▸ Cefalexin 2 g OR ▸ Clindamycin 600 mg OR ▸ Azithromycin 500 mg OR ▸ Clarithromycin 500 mg ▸ Cefazolin 1 g IM or IV OR ▸ Ceftriaxone 1 g IM or IV OR ▸ Clindamycin 600 mg IM or IV

Do's

• Elicit a full medical history to identify the minor Duke criteria for the diagnosis.
• Consider alternative diagnoses for bacteremia and fever by searching for focus of infections.
• Initiate antibiotic therapy after withdrawing blood for culture (Class I, level of evidence B).

• If the blood cultures are negative in a patient suspected to have infective endocarditis, suspect HACEK infection and ask the laboratory to retain the blood cultures for more than two weeks.

• 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.

• Do a TEE intraoperatively among patients scheduled for valve surgery for infective endocarditis (Class I, level of evidence B).

• Consider ordering a cardiac CT scan when echocardiography does not provide clear details about the cardiac anatomy in the context of suspected paravalvular infections (Class IIa, level of evidence B).

Dont's

• Don't administer prophylaxis for infective endocarditis in patients with valvular heart disease who are at risk infective endocarditis for procedures such as TEE, cystoscopy, esophagogastroduodenoscopy or colonoscopy without any evidence of active infection (Class III; level of evidence B).

• 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

• Do not administer infective endocarditis prophylaxis for procedures involving the respiratory tract unless they involve incision of the respiratory tract mucosa.

• Do not administer cephalosporins in subjects with a previous history of anaphylaxis, angioedema, or urticaria following penicillin or ampicillin use.

References

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