Notes - Infective Endocarditis

AETIOLOGY

·          Dental disease or procedure

o   Alpha haemolytic Streptococcus viridians

·         Prosthetic valves –

o   Early < 60 days –

§  Staphylococcus aureus

§  Staphylococcus epidermidis

o   Late > 60 days

§  Streptococcus viridians

§  Staphylococcus aureus

·         Intravenous drug abuse, long standing IV cannulae and soft tissue infections (DM)

o   Staphylococcus aureus

o   Candida (rare)

·         Cardiac surgery

·         Permanent pacemakers

·         Genitourinary disease or procedure

o   Enterococcus faecalis

·         Bowel malignancy

o   Streptococcus bovis

·         Rare causes – HACEK Group

o   Haemophilus species

o   Actinobacillus actinomycetemcomitans

o   Cardiobacterium hominis

o   Eikenella corrodens

o   Kingella kingae

·         Culture negative BE

o   Prior antibiotic therapy

o   Fastidious organisms

§  Coxiella burnetti (Q fever)

§  Chlamydia species

§  Bartonella species (trench fever and cat scratch disease)

§  Legonella

SYMPTOMS

·         Fever – Pyrexia of unknown origin

·         Malaise

·         Features of cardiac failure

o   Ankle swelling

o   Shortness of breath

·         Arthralgia

·         Abdominal discomfort (splenomagally)

·         Strokes

·         Haematuria

SIGNS

EXAMINATION

GENERAL EXAMINATION

·         Eye –

o   Roth spots - retinal hemorrhages with white or pale centers composed of coagulated fibrin.

o   Conjunctival splinter haemorrhages

·         Poor dental hygiene

·         Venipuncture marks

·         Tattoos

·         Petechiae - on the legs & the chest wall

·         Clubbing

·         Splinter haemorrhages

·         Osler nodes - On pads of fingers & toes, and thenar & hypothenar eminences.

·         Janeway lesions - Hemorrhagic raised lesions in palms & soles

·         Ankle swelling

CARDIOVASCULAR SYSTEM EXAMINATION

·         Murmur

INVESTIGATIONS

To

1.      Confirm diagnosis

2.      To identify the organism

3.      Monitor response to therapy

Tests

·         Blood cultures

a.      Three sets (6 bottles) from three sites

·         Serological tests

a.      When blood cultures are negative

b.      Coxiella, Bartonella, Legionella, Chlamydia

·         FBC

a.      Mild normochromic normocytic anaemia

b.      Polymorphonuclear leukocytosis

c.       Thrombocytopaenia

d.      Thrombocytosis

·         Blood urea - sepsis

·         Serum electrolytes – sepsis

·         Liver biochemistry – Increased ALP

·         CRP & ESR –

a.      increased

b.      CRP – to assess response to therapy

·         Urine full report

a.      Proteinuria

b.      Haematuria

·         PCR – culture negative IE

·         Echocardiogram

a.      Transthoracic

                                                              i.      Visualize vegetations

                                                            ii.      Valvular dysfunction

                                                          iii.      Abscessed

b.      Transoesophageal

                                                              i.      Higher sensitivity and specificity for abscess formation

·         Chest X-ray

a.      Evidence of heart failure

b.      Multiple pulmonary emboli – right sides endocarditis

c.       Pulmonary infiltrates

·         Electrocardiography

a.      MI

b.      Conductive defects

DIAGNOSIS

1.     Microorganism positive in culture of a specimen of a vegetation, embolism or intracardiac abscess

2.     Active endocarditis seen in histology of vegetation or intracardiac abscess

3.     2M + 1m

4.     1M + 3m

5.     5m

·         5 Major Criteria (M)

1.      A positive blood culture for infective endocarditis – Typical microorganisms in 2 separate blood cultures

2.      A persistently positive blood cultures –

§  In 2 samples obtained 12 hours apart

§  In all 3 or majority of 4 or more separate samples with 1^st and last taken at least 1 hour apart

3.      Positive serological test for Q fever

4.      Echocardiographic evidence of endocardial involvement

5.      New valvular regurgitation

·         6 Minor Criteria (m)

1.      Predisposing heart condition or IV drug use

2.      Fever ≥ 38 ⁰ C

3.      Vascular phenomena

4.      Immunologic phenomena

5.      Microbiological evidence

6.      Endocardiogram

TREATMENT

·         Antibiotic treatment for 4 – 6 weeks

1.      No suspicion of Staphylococci – Penicillin, Gentamycin

2.      Suspected Staphylococci – Vancomycin, gentamycin

3.      Streptococcal – Penicillin, gentamycin

4.      Enterococcal – Amlicillin/ amoxicillin, Gentamycin

5.      Staphyloccocal – Vancomycin, Flucloxacillin, Benzylpenicillin + Gentamycin

·         Monitor serum levels of Gentamycin and vancomycin to ensure adequet therapy and prevent toxicity

·         Penicillin allergy – vancomycin or teicoplanin

Response to treatment

·         Should respond within 48 hours

o   Resolution of fever

o   Reduction of ESR and CRP

·         If not,

o   Perivalvular extension and abscess formation

o   Drug reaction

o   Nosocomial infection

o   Pulmonary embolism

o   Take cardiothoracic opinion

Surgery

References:

·         Kumar P, Clark M, 2009, Clinical Medicine, 7^th edition, Saunders Elsevier, pp 769 - 773