Infective Endocarditis: Duke Criteria, Echo Findings & Antibiotic Protocols

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Below is your **complete, concise-but-exhaustive** NEET PG–ready reference for **Infective Endocarditis (IE)** following your preferred pattern. --- # **Infective Endocarditis (IE): Duke Criteria, Echo Findings & Antibiotic Protocols** --- # **1. Definition** Infective endocarditis is an infection of the **endocardial surface of the heart**, typically involving heart valves, caused by **bacteria** or **fungi**, leading to vegetation formation, valvular destruction, and systemic embolization. --- # **2. Pathophysiology** 1. **Endothelial injury** → deposition of platelets & fibrin → **nonbacterial thrombotic endocarditis (NBTE)**. 2. **Bacteremia** (transient/persistent) → organisms adhere to NBTE → **vegetation formation**. 3. Vegetations protect microbes → high bacterial load, low immune clearance → **metastatic emboli**, immune complex deposits, valvular dysfunction leading to **heart failure**. Common organisms: * **Native valve**: *S. aureus*, Viridans streptococci, *Enterococcus*. * **Prosthetic valve (early <1 yr)**: *S. aureus*, coagulase-negative staph. * **IV drug users**: *S. aureus* (Tricuspid). * **Culture-negative**: HACEK group, Coxiella, Bartonella, Brucella. --- # **3. Clinical Features** ### **Constitutional** * Fever, chills, night sweats * Weight loss, malaise ### **Cardiac** * New or changing **murmur** * **Heart failure** due to severe valvular regurgitation * Conduction block (abscess) ### **Peripheral signs** * **Janeway lesions** (painless palms/soles emboli) * **Osler nodes** (painful immunologic nodules) * **Roth spots** (retinal hemorrhages) * **Splinter hemorrhages** * **Petechiae** ### **Embolic manifestations** * Stroke, splenic infarct, renal infarct, pulmonary emboli (right-sided IE) ### **Immune complex manifestations** * GN (hematuria, proteinuria) * Positive RF * Low complement --- # **4. Modified Duke Criteria (Diagnosis)** Diagnosis requires: ### **✔ Definite IE** * 2 Major OR * 1 Major + 3 Minor OR * 5 Minor --- ### **Major Criteria** 1. **Positive Blood Cultures** * Typical organism (Viridans strep, S. aureus, HACEK) **from 2 separate cultures** OR * Persistently positive cultures (2 drawn 12 hrs apart) 2. **Evidence of Endocardial Involvement** * **Echo** showing: * Vegetation * Abscess * New partial dehiscence of prosthetic valve * **New valvular regurgitation** --- ### **Minor Criteria** * Predisposition: heart disease / IV drug use * Fever ≥38°C * Vascular phenomena: emboli, Janeway, septic pulmonary infarcts * Immunological phenomena: Osler nodes, Roth spots, GN, RF+ * Microbiology not fulfilling major criteria --- # **5. Echocardiographic Findings** ### **Transthoracic Echo (TTE)** * First-line * Sensitivity ~60% ### **Transesophageal Echo (TEE)** * GOLD STANDARD * Sensitivity ~90–100% * Mandatory if: * Prosthetic valve * Prior TTE negative but high suspicion * Staph aureus bacteremia * Poor acoustic window ### **Echo Findings in IE** * **Vegetations**: oscillating intracardiac mass attached to valve * **Regurgitation** (MR/AR/TR) * **Abscess cavity** (perivalvular) * **Perforation** of valve leaflet * **Prosthetic valve dehiscence** (rocking motion) * **Pseudoaneurysm** --- # **6. Investigations** * Blood cultures × **3 sets** before antibiotics * CBC: anemia, leukocytosis * ESR/CRP elevated * Renal function * Urinalysis (microscopic hematuria) * ECG: conduction block suggests abscess * CT/MRI: embolic events --- # **7. Management (Complete Stepwise)** ## **1️⃣ Initial Measures** * Take **3 sets of blood cultures BEFORE antibiotics**. * Start **empiric IV antibiotics** if patient is sick or high suspicion. --- # **8. Empiric Antibiotic Therapy** ## **Native Valve IE** * **Ceftriaxone + Vancomycin** OR * **Vancomycin + Gentamicin** (rarely now) ## **Prosthetic Valve IE** * **Vancomycin + Gentamicin + Cefepime** OR * Add **Rifampicin** for staphylococcal prosthetic valve IE. ## **IV Drug User (Tricuspid)** * **Vancomycin** (cover MRSA) --- # **9. Targeted Therapy (Organism-Specific)** ### **1. Viridans streptococci / S. bovis** * **Ceftriaxone** IV 4 weeks OR * **Penicillin G** 4 weeks * Add **gentamicin** for 2 weeks in severe infection. --- ### **2. Staphylococcus aureus** **MSSA** * **Nafcillin/Oxacillin** 4–6 weeks OR * **Cefazolin** (if non-anaphylactic penicillin allergy) **MRSA** * **Vancomycin** 4–6 weeks OR * **Daptomycin** --- ### **3. Enterococcus** * **Ampicillin + Gentamicin** OR * **Ampicillin + Ceftriaxone** (preferred due to less nephrotoxicity) Duration: **6 weeks** --- ### **4. HACEK organisms** * **Ceftriaxone** 4 weeks OR * **Ampicillin-sulbactam** --- ### **5. Culture-Negative IE** * Early (<1 yr): **Vancomycin + Gentamicin + Cefepime** * Late: **Vancomycin + Ceftriaxone** --- # **10. Indications for Surgery (Very Important for NEET PG)** ### **Absolute indications** * **Refractory heart failure** from valve dysfunction * **Uncontrolled infection**, e.g., * Abscess * Persistent bacteremia >72 hrs * Fungal IE ### **Prevention of embolization** * Large vegetation >10 mm with embolic events * Vegetation >15 mm even without emboli ### **Prosthetic valve IE with dehiscence** --- # **11. Complications** * Heart failure * Septic emboli (stroke, splenic infarct) * Mycotic aneurysm * Perivalvular abscess * Conduction block * Renal failure (GN) * Death --- # **12. Prophylaxis (AHA Guidelines)** Indicated ONLY for high-risk patients: * Prosthetic heart valves * Previous IE * Congenital cyanotic heart disease * Cardiac transplant with valvulopathy **Procedure requiring prophylaxis:** Dental work involving gingiva **Drug:** **Amoxicillin 2 g PO** 30–60 mins before --- If you want **HTML–CSS–JS MCQs**, **SEO tags**, or **image generation**, tell me — I will create them in your preferred one-file format.