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MI 3.1 - Infective endocarditis: causative organisms, pathogenesis, diagnosis, treatment • MI 3.2 - Rheumatic fever and Streptococcus pyogenes In dono competency ko mujhe apporba sastry book ke according conceptually samjhao poori detail me concepts and flowchart ke saath

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Dono competencies poori detail mein cover ho gayi hain. Yahan ek comprehensive summary hai:

Dono Competencies - Final Summary

Note: Apurba Sastry ki book directly library mein available nahi thi, lekin Medical Microbiology 9e (Murray), Robbins Pathology, aur Jawetz ka content use kiya gaya hai - ye sab Apurba Sastry ke syllabus ke fully aligned standard references hain.

MI 3.1 - INFECTIVE ENDOCARDITIS - Key Points

Definition: Heart valve/endocardium ka microbial infection jisme vegetations banti hain.
Causative Organisms:
  • Viridans Streptococci (50-60%) → Subacute IE, damaged valves, community
  • S. aureus → Acute IE, healthy valves, healthcare/IVDU settings (ab most common overall)
  • Enterococcus → GI/GU procedures
  • HACEK group (oral commensals) → Subacute IE
  • Culture-negative (~10%) → Prior antibiotics
Pathogenesis ka core:
  1. Predisposed heart (MVP = now #1 risk factor) → turbulent flow → endothelial damage
  2. Sterile fibrin-platelet thrombus (NBTE) forms
  3. Bacteremia → bacteria adhere → multiply inside thrombus (protected from phagocytes)
  4. Large, friable vegetation = organisms + fibrin + inflammatory cells
Clinical features ka trick: JROP-S = Janeway (painless), Roth spots, Osler (painful), Petechiae, Splinter hemorrhages + Fever (most consistent) + Murmur (90% left-sided)
Diagnosis: Blood culture (most important, 3 sets before antibiotics) + Echocardiography (TEE more sensitive) + Modified Duke Criteria
Treatment: Bactericidal antibiotics, 4-6 weeks. Viridans Strep → Penicillin G; MRSA → Vancomycin; Fungal → Ampho B + surgery

MI 3.2 - RHEUMATIC FEVER & S. PYOGENES - Key Points

S. pyogenes (Group A Strep - GAS):
  • Gram+ cocci in chains, beta-hemolytic, catalase-negative, PYR+, Bacitracin-sensitive
  • M protein = most important virulence factor (anti-phagocytic + rheumatogenic)
  • Streptolysin O → antigenic → ASO test; Streptolysin S → blood agar hemolysis
  • Suppurative diseases: Pharyngitis, Impetigo, Necrotizing fasciitis, Scarlet fever, STSS
  • Non-suppurative: Rheumatic Fever (pharyngitis only) + AGN (pharyngitis + skin)
Rheumatic Fever:
  • Mechanism = Molecular Mimicry - M protein antibodies cross-react with cardiac myosin/valve proteins
  • Only pharyngitis → RF (NOT skin infections)
  • Jones Criteria = 2 Major OR 1 Major + 2 Minor + evidence of GAS
    • Major: Carditis (most serious), Arthritis (most common), Chorea, Erythema marginatum, Subcutaneous nodules
  • Aschoff body (with Anitschkow cells) = pathognomonic of RF carditis
  • Mitral stenosis = most common long-term RHD valve lesion
  • Treatment: Penicillin + Aspirin (arthritis) / Steroids (carditis)
  • Secondary prophylaxis: Benzathine Penicillin G IM every 4 weeks - lifelong if valvular disease
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