Sub acute bacterial Endocarditis(SBE) - Long Case With Questions & Answers

Clinical History:
Mr …, 28-year-old, student, normotensive, nondiabetic, nonsmoker, presented with fever for 1 month, which is low grade, continued, sometimes associated with chills and rigor, also with profuse
sweating, subsides only with paracetamol, highest recorded temperature was 101F. He also complains
of central chest pain, sharp in nature without any radiation, does not aggravate by cough or movement of the chest. He also experiences occasional palpitation, associated with difficulty in breathing after mild to moderate exertion for the last few months, which are relieved by taking rest. There is no history suggestive of orthopnea or paroxysmal nocturnal dyspnea. For the last 2 months, the patient also experiences malaise, generalized weakness, arthralgia, myalgia, anorexia and substantial loss of weight.
There is no history of unconsciousness, hematuria or loin pain (differentiates from embolic phenomena). He does not give any history of dental procedures or cardiac or other surgery or
instrumental procedure (catheterization, colonoscopy, cannula, etc.) or any history of intravenous drug abuse. His bowel and bladder habits are normal.
He has been suffering from some valvular heart disease for several years. There is no family history of such illness. He used to take frusemide, propranolol and vitamins prescribed by the local physicians.

Examination: 
Patient is ill looking, emaciated and toxic, with moderate anemia. There is generalized clubbing: involving all the fingers and toes and there are two splinter hemorrhages in the left index finger.
No cyanosis, jaundice, koilonychia, leukonychia, lymphadenopathy or thyromegaly.
-Pulse: 110/min.
- Blood pressure: 95/75 mm Hg.
- Respiratory rate: 28/min.
- Temperature: 100°F.

On cardiovascular examination a murmur was detected on auscultation.

Provisional Diagnosis: Sub acute bacterial Endocarditis(SBE)

Points supporting the diagnosis:

• The patient is a known case of some valvular heart disease (as mentioned in history)
• Fever which is not responding to multiple antibiotics
• Associated features like clubbing, splinter hemorrhage, cardiac murmur, 

Remember, in any patient with prolong fever, which is not responding to usual therapy,

SBE should be considered if there are:

¯¯ History of previous cardiac lesion

¯¯ Appearance of a new murmur

¯¯ Change in the nature of a pre-existing murmur

What are your differential diagnoses?

As follows (any cause of PUO should be considered. Common possibilities are):

• Tuberculosis
• kala-azar
• Malaria
• Collagen disease (SLE)
• Lymphoma

What investigations should be done to diagnose SBE?

As follows:

• CBC ; Hb%, TC, DC, ESR (normochromic normocytic anemia, neutrophil leukocytosis, high ESR may be present).
• Serum CRP (increased. It is more reliable than ESR in monitoring progress).
• Blood culture (both aerobic and anaerobic)—3 cultures from different sites at 1 hour apart during peak fever, taken after all aseptic measures (10 to 20 ml blood is taken each time). If possible, both aerobic and anaerobic cultures should be done. In some cases, fungal culture should also be done. 10% are culture negative.
• Echocardiography (to see vegetation, valvular lesion or congenital anomaly). Transesophageal
• echocardiography is more sensitive than transthoracic echocardiography. TOE is mandatory in case of doubtful case, prosthetic or pacemaker endocarditis or when an abscess is suspected. The sensitivity of transthoracic echo is about 55 to 65%, but that of transesophageal echo is more than 90%.
• Urine DR (hematuria and proteinuria may be present).
• CXR P/A view (may show cardiomegaly or evidence of cardiac failure).
• ECG: may show prolong PR interval (AV block due to aortic root abscess formation) and occasionally infarction (due to emboli).
• Urea and creatinine.

What are the predisposing factors or causes of SBE?

Causes or predisposing factors are as follows:

• Rheumatic valve lesion (e.g. AR, MR, etc.).
• Congenital heart disease (VSD, PDA, bicuspid aortic valve, coarctation of aorta, TOF. SBE is rare in ASD, PS, MS, AS).
• Prosthetic valve.
• Dental extraction.
• Instrumentation (catheterization, sigmoidoscopy, cystoscopy, endoscopy, cannulation).
• Cardiac surgery or cardiac catheterization.
• IV drug abuse (right sided endocarditis is more common, especially involves tricuspid valve).

What are the organisms causing infective endocarditis?

As follows:

1. Subacute bacterial endocarditis:

• Streptococcus viridans (S. sanguis, S. mitis)—the most common (35 to 50%)
• Enterococcus faecalis, E. faecium
• S. bovis, S. milleri and other streptococci
• S. aureus or epidermidis
• Diphtheroids
• HACEK organism (Haemophilus, actinobacillus, cardiobacterium hominis, eikenella, kingella).

2. Acute bacterial endocarditis:

• S. aureus (the most common)
• Pseudomonas
• Candida
• S. pneumoneae
• Neisseria gonorrhoea

3. Postoperative endocarditis:

• S. albus
• Candida
• Aspergillus
• All other organisms causing subacute and acute endocarditis.

What are the signs in the hand in SBE?

As follows:

• Clubbing (a late sign).
• Osler’s node (small painful violaceous raised nodule, 0.5 to 1.5 cm, present on the tip of the fingers, palmar aspect and tip of the toes, probably due to the product of vasculitis or septic embolism).
• Splinter hemorrhage (subungual).
• Janeway lesion (large painless erythematous macules on the palm and sole).
• Patechial hemorrhage.
• Infarction due to embolism.

What is vegetation?

It is a small solid mass composed of platelet, fibrin and organism, occurring at the site of endothelial

damage in the valve or endocardium. It may result in embolism.

What are the causes of culture negative endocarditis?

As follows:

• Prior antibiotic treatment (common cause).
• Fungal, yeast, anaerobic infection or Q fever (needs special culture).
• Right sided endocarditis.
• Non-infective endocarditis: Libmann Sac (non-bacterial verrucous endocarditis in SLE, which is usually associated with antiphospholipid antibody syndrome), marantic endocarditis (non-bacterial thrombotic or verrucous endocarditis found in malignancy, such as bronchial carcinoma).

What are the complications of SBE?

As follows:

• Heart failure (LVF is a common cause of death).
• Valve destruction, regurgitation, obstruction.
• Aortic root abscess, may lead to prolongation of PR interval or even complete AV block.
• Systemic embolism.
• Right sided endocarditis usually involves the pulmonary valve and may cause septic pulmonary emboli, occasionally with infarction and lung abscess.
• Vasculitis.

How to treat SBE?

As follows:

1. Antibiotic:

• Ideally antibiotic should be given according to culture and sensitivity. However, treatment should be started as soon as the blood sample is sent for culture and sensitivity. In subacute cases, benzylpenicillin 1.2 g IV 4 hourly and gentamicin 1 mg/kg IV 8 hourly for 4 weeks is given. In acute cases, flucloxacillin 2 g IV 6 hourly is added to cover staphylococci. In case of penicillin allergy, a prosthetic valve or suspected methicillin-resistant staphylococcus aureus (MRSA) infection, triple therapy with vancomycin, gentamicin and oral rifampicin should be considered.
• Another regimen of empirical therapy—vancomycin 1 g 12 hourly IV with ceftriaxone 2 g every 24 hours is a good choice pending definitive diagnosis.
• For viridans streptococci, ceftriaxone 2 g once daily IV or IM for 4 weeks is effective. In penicillin allergic patients, vancomycin 15 mg/kg IV 12 hourly for 4 weeks is given. In prosthetic valve endocarditis, penicillin for 6 weeks and gentamicin for 2 weeks should be given.
• For HACEK organisms, ceftriaxone 2 g IV once daily for 4 weeks are given. If prosthetic valve is involved, then treatment should be given for 6 weeks.
• Q fever endocarditis needs prolong treatment with doxycycline and rifampicin or ciprofloxacin. Even then, organisms are not always eradicated. Valve surgery is often required.

2. Other antibiotic may be given according to the suspicion of the cause.

3. Any source of infection (e.g. a tooth with an apical abscess) should be removed as soon as possible.

4. Other supportive treatment should be given accordingly.

5. Treatment of the underlying cause like valvular disease.

What preventive measures should be taken during dental procedure?

Routine antibiotic prophylaxis prior to dental procedure is no longer recommended as this has not

been proven to be effective. However, in few high risk cases antibiotic prophylaxis may be considered.

These are:

• Prosthetic cardiac valve.
• Previous infective endocarditis.
• Congenital heart disease (CHD)—unrepaired cyanotic CHD, completely repaired CHD with prosthetic material or device or repaired CHD with residual defects at the site or adjacent to the site of a prosthetic patch or prosthetic device.
• Cardiac transplantation recipient in whom cardiac valvulopathy develops.

Drugs used for prophylaxis:

• Amoxicillin 2 g 1 hour before procedure.
• If penicillin allergy—clindamycin 600 mg or cephalexin 2 gm or azithromycin or clarithromycin 500 mg 1 hour before procedure.
• If the patient is unable to take by mouth, parenteral therapy may be given with ampicillin 2 g IV or IM 30 minutes before the procedure. In case of penicillin allergy, clindamycin 600 mg IV 1 hour before procedure or cefazolin 1 g IM or IV 30 minutes before procedure

What are the indications of cardiac surgery in infective endocarditis?

Surgery (debridement of infected material and valve replacement) is indicated in following conditions:

• Progressive heart failure from valve damage
• Valvular obstruction
• Repeated embolization
• Fungal endocarditis
• Persistent bacteremia in spite of adequate antibiotic therapy
• Myocardial abscess
• Endocarditis of prosthetic valve
• Large vegetation in left sided valve.