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Infective Endocarditis - NEET PG Medicine

Feb 09, 2023

Infective Endocarditis - NEET PG Medicine

Infective endocarditis is considered important for the NEET PG exam because it is a high-yield topic. Endocarditis is a common topic in postgraduate medical exams, as it covers several important concepts such as microbiology, pathology, clinical presentation, diagnosis, and management. Plus, endocarditis is a multidisciplinary subject that requires knowledge of various medical disciplines, such as cardiology, infectious diseases, and surgery.

Therefore, a strong understanding of infective endocarditis is essential for NEET PG aspirants in order to answer the related questions accurately in exams.

Read this blog further and get a quick overview of the topic and enhance your NEET PG Preparation.

Infective Endocarditis

  • Modified Duke criteria for diagnosis 
  • Traditionally in Jones criteria – Clinical features are major ones 
  • But in infective endocarditis:  Duke criteria - Investigation are major ones 

The Modified Duke Criteria for the Diagnosis of Endocarditis 

Major Criteria 

  • Blood culture positive for IE
    • Typical microorganism consistent with IE from two separate blood cultures 
      • Virdians streptococci; Streptococcus bovis, HACEK group, Staphylococcus aureus, or 
      • Community – Acquired enterococci, in the absence of a primary focus 
    • Microorganism consistent with IE from persistently positive blood cultures, defined as follows:
      • At least two positive blood culture of blood samples drawn >12 h apart, or 
      • All of three or a majority of ≥ 4 separate cultures of blood (with first and last sample drawn at least 1 h apart)
    • Single positive blood culture for Coxiella burnetii or antiphase I IgE antibody titer > 1:800
  • Evidence of endocardial involvement 
  • Echocardiogram positive for IE (TEE recommended in patients with prosthetic valves, rated at least “possible IE” by clinical criteria, or complicated IE [paravalvular abscess]; TTE as first test in other patients), defined as follows:
    • 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
    • New valvular regurgitation (worsening or changing or pre-existing murmur not sufficient)

Minor Criteria 

  •  Predisposition, predisposing heart condition or injection drug use 
  • Fever, temperature >38°C
  • Vascular phenomena, major arterial emboli, septic pulmonary infarcts, mycotic aneurysm, intracranial hemorrhage, Conjunctival hemorrhages, and Janeway lesions 
  • Immunologic phenomena: Glomerulonephritis, Osler nodes, Roth’s spots, and rheumatoid factor 
  • Microbiological evidence: Positive blood culture but does not meet a major criterion as noted previously (excluding single positive cultures for coagulase – negative staphylococci and organism that do not cause endocarditis) or serologic evidence of active infection with organism consistent with IE 
  • Echocardiographic minor criteria eliminated 
  • If subacute bacterial endocarditis: Strep. Viridians 
  • Acute bacterial endocarditis 
    • A person admitted in hospital & subsequently there has been episodes - Staph. Aureus 
  • If not, hospital acquired (community prospective) → Streptococcus
  • IV drug user, right sided infective endocarditis – Tricuspid valve affected →because person may not maintain hygiene 
  • As a result, if he is taking IV drug, infection going into right side of heart 
    • Organism – Staph. aureus
  • Coagulase negative Staph – For prosthetic development of carditis 
  • Traditionally multiple blood culture is taken, at least all 3 out of 4 at 1 to 2 hours 
    • Time Gap is important – To prove heart is source of bacteria into systemic circulation
    • All 3 reports need to be positive with the same organism. 
    • But if only 1 culture report is positive out of 3 & from which organism could be suspected, then it is organism causing Q fever, that is Coxiella burnetii
  • Echocardiographic findings 
    • Bacteria & fibrin growing on surface of heart valves 
    • Aortic valve is having vegetation 
    • This vegetation can grow deeper & can grow into tissue of values (value abscess)
  • Valve abscess / ring abscess with respect to infective endocarditis → Infection is deep seated & causing extensive problems in patients 
Valve abscess
  • Extensive problems – Bacteria is eating away on tissue of valve – Result in perforation. It is not standard aortic regurgitation where valve leaflet apposition is affected. In this condition as far as valve leaflet of apposition is concerned there is no problem 
  • In rheumatic – Cusp of valve or Tip of valve is involved – Commissural involvement. But in this condition – Commissural end of the cusp is touching is not a problem. Rather there is perforation in valve leaflet which will cause blood to go back into left ventricle 
  • In a normal healthy person – Not a single drop of blood goes from the aorta to the left ventricle. But here there is leakage of blood. Therefore, there is new onset murmur – Major diagnostic without criteria.


 Summary of major diagnostic criteria 

Following is a summary of the major criterias used for the diagnosis of infective endocarditis: 

  1. Blood culture: Isolate organism 
  2. Echocardiographic evidence: New onset murmur, preexisting murmur worsened because valve leaflet in person has been affected 
  3. New onset valvular lesion 

Minor criteria 

  • Fever 
  • Predisposition – May be not only be IV drug usage
    • This may be known case of Rheumatic heart disease who has been having fever for part 2 weeks 
    • This is an alcoholic with structural heart disease & he is been running fever
    • Anytime there is structural damage to heart there is structural damage to valve leaflet & infective endocarditis will intervene
  • Vascular phenomenon – Janeway lesion 
    • It is seen in palms & soles of patient 
    • It is erythematous macules in palms & in soles 
  • Immunological criteria: ROG
    • Roth’s spots, positive rheumatoid factor (biologically false positive)
    • O – Osler nodes – In pulp of finger or fingertips 
    • G – Glomerulonephritis
  • It looks hematuria as word, infective endocarditis is of heart
    • RBC in urine because there is glomerulonephritis 
  • Roth’s spots – Minor diagnostic criteria because they are found on fundus examination 
    • Can also be seen in Anemia, leukemia, infective endocarditis 
    • So it is a common finding on fundus examination because it is found in other conditions also therefore it is minor diagnostic criteria.
  • If cultures are not satisfying the diagnostic criteria 
    • For diagnosis of this condition 
      • 1 major criteria + 3 minor criteria 
    • Possibility – Person has antibiotics before he came
    • As a result, blood culture might be sterile & vegetations < 2mm – may not be seen on echocardiography 
  • If vegetation is small – No perforation in valve leaflet. So, if no perforation in leaflet – New onset murmur will also not be happening. If major criteria are not present, then diagnosis is based on basis of ‘5’ minor criteria 
  • Laboratory test – Positive in form of blood culture or echocardiography 
  • Any 1 if present is sufficient for diagnosis 
  • Infective Endocarditis (IE) α mathematical shunt gradient 
    • Mitral regurgitation – Valvular heart condition operating at highest-pressure gradient, so highest chances of IE will be present 
    • AST – Low pressure shunt so gradient will be relatively lesser therefore the chances of IE will also be lesser.
  • People having pre-existing heart disease, prosthetic heart valves – These patients should be taking special prevention whenever they are going in for dental procedure like a person having cavity in tooth or he is having root canal treatment.
  • There is pulp abscess also because if a person is having dental caries – During dental procedure there could be possibility of inoculation of bacteria into the bloodstream & they could cause damage to the heart. As a result, in patient of dental caries for the procedure ampicillin (2 gm, 1 hour before procedure is given)
  • Reason – To mitigate the risk of development of damage to the heart valves. This prophylaxis is valid for dental procedures only however it is not valid for Genito – Urinary procedure.
  • If a person is going under cystoscopy or colonoscopy - antibiotic prophylaxis is not given 
  • Any person with prosthetic heart valve disease 
    • Artificial valve is present, there are chances for it to get destroyed.
  • This device is used for heart failure so this is the device of heart
  • Left ventricular assist device (LAVD)- Useful for heart failure patients which is so severe that they need a transplantation. But before they get brain dead donor, a bridge is needed i.e., Ventricle or LVAD (Left Ventricular Assist Device)
  • Specialty for prosthetic heart valve & LV assist device - In both these conditions there is device in the heart. Because an artificial heart valve is put in, it should be prevented from any type of disintegration. Similarly with prior endocarditis – Because there is already damage in the heart valve.

Also Read: Myocardial Infarction - Neet PG Medicine

EPILEPSY AND Electroencephalography (EEG) : NEET PG Medicine

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