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.
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
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
New partial dehiscence of prosthetic valve
New valvular regurgitation (worsening or changing or pre-existing murmur not sufficient)
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
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
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.
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
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.
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