Infective Endocarditis Flashcards
1
Q
Definition
A
- Infective Endocarditis is an Infection of the Endocardial Surface of the Heart: Endovascular Infection of Cardiovascular structures, including Cardiac Valves, Atrial and Ventricular Endocardium, Septal Defect, Large Intrathoracic Vessels and Intracardiac Foreign Bodies, such as Prosthetic Valves, Pacemaker Leads and Surgical Conduits.
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2
Q
Epidemiology
A
- The annular incidence in the UK is 3-10/100,000 but higher in developing countries.
- Men are 2.5 x more likely to be affected than women
- In hospital Mortality 15-30%
- 95% left side of heart
- 50% subacute
- IE is a relatively uncommon infection, but carrie ssignficiant complications (Septic, Shock, Embolic Disease including Stroke, Valvular HF)
- Without treatment, Mortality approaches 100% ie it is inevitably fatal; even with treatment there is a significant Morbidity and Mortality
3
Q
Aetiology
A
- Endocarditis is usually the consequence of 2 factors: The Presence of Organisms in the Bloodstream, and Abnormal Cardiac Endothelium that facilitates their Adherence and Growth
- Bacteremia may arise for Patient-Specific Reasons (Poor Dental Hygiene, IV Drug use), Soft Tissue Infections)
- OR may be a/w Diagnostic or Therapeutic Procedures (Dental Tx, Intravascular Cannulae, Cardiac Surgery or Permanent Pacemakers)
- Previously damaged tissue (previous IE, Surgery) or Non-Native Structures (Valve Replacement) are predisposed to infection
- Damaged Endocardium promotes Platelet and Fibrin Deposition which allows Organisms to Adhere and Grow, leading to an Infected Vegetation
- So Valves/Endocardial surfaces become infected after exposure to micoemboli from Bacteria or fungi circulating in the bloodstream)
- Certain Bacteria have Virulence factors or Adherence factors that increase likelihood of colonization of tissue
- Organisms Prolieferate int eh evolving thrombus and their persistent shedding into the Bloodstream causes Immune Response resulting in symptoms
- Valvular Lesions may create Non-Laminar Flow, and Jet Lesions from Septal Defects or a PDA result in Abnormal Vascular Endothelium
- Aortic and Mitral Valves are most commonly involved in IE; IVDU are the exception, as Right-Sided Lesions are more common in these patients
- The Epidemiological Profile of IE has changed over the last few years
- Newer factors, such as valve Prosthesis, IVDU and Intra-Cardiac Devices are associated with increased use of Invasive Procedures increasing the risk for Opportunistic Bacteremia
- Healthcare-Acquired IE is a growing demographic representing up to 30% of IE, justifying the use of Aseptic measures during Venous Catheter procedures and any Invasive Procedures
4
Q
Risk Factors: Sources of Bacteremia
A
- IVDU
- Surgical Procedure
- Termination of Pregnancy
- Age >60
- Structural Heart Disease
- Valvular HD
- Previous Endocarditis
- Chronic Hemodialysis
- Immunocompromised Individuals (Fungi increased prevalence)
- Bowel Cancer
5
Q
Organisms
A
- Staphylococci (30-50%)
- S. Aureus (31%); most aggressive organism
- Coagulase Negative Staph (11%)
- Mitral > Aortic
- S. Epidermis + Auereus most common in Prosthetic Valve
- Streptococi 20-30%
- Strep Viridans (most common, and seen in Subacute disease)
- Strep. Sanguis, Strep Mitis, Strep Mutans, Strep Milleri
- Enterococal Endocarditis
- Enterococcus Faecalis, Enterococcus Faecium
- a/w Lower GI or GU Disease and Bowel Malignancy or after Invasive Procedures
- Males > Females
- Fungi
- Candida, Aspergillus, Histoplasma
- Immunocompromised patients
- Rare causes -→ These include the HACEK group of organisms, which tend to run a more insidious course (Box 30.45).
- Haemophilus spp
- Actinobacillus sp
- Cardiovacterium Hominis
- Eikenella Corredens
- Kingella King
- Culture Negativ eEndocarditis
- This account for 5-10% of Endocarditis cases
- The usual cause is Prior Antibiotic Therapy (Good History Taking is vital) but some cases are due to a variety of Fastidious Organisms that fail to grow in normal blood cultures.
- These include Coxiella burnetii
(the cause of Q fever), Chlamydia species, Bartonella species (organisms that cause trench fever and cat scratch disease) and Legionella.
6
Q
Dukes Criteria: Definite diagnosis of IE
A
- Pathologival evidence on Histological examination of a Vegetation or an Intracardiac Abscess
- 2 major criteria
- 1 major and 3 minor
- 5 minor
7
Q
Dukes Criteria: Possible IE
A
- 1 major criteria with 1 minor
- 3 minor
8
Q
Modified Duke Criteria for Endocarditis: Major
A
- Typical Organisms from 2 separate BC → A Positive Blood Culture for IE, as defined by the recovery of a typical microorganism from Two separate blood cultures in the absence of a primary focus (Viridans Streptococci, Abiotrophia species and Granulicatella species; Streptococcus Bovis, HACEK Group B, or Community-Acquired Staphylococcus Aureus or enterococcus species)
- OR Microorganisms consistent with IE from persistently Positive BC → A persistently Positive Blood Culture, defined as the recovery of a microorganism consistent with endocarditis either from blood samples obtained more than 12 h apart or from all three or a majority of four or more separate blood samples, with the first and last obtained at least 1 h apart
- or SINGLE positive BC for Coxiella Burnetti → A positive serological test for Qfever , with an immunofluorescence assay showing phase 1 immunoglobulin G antibodies at a titre >1:800
- or Echocardiographic evidence of endocardial involvement:
- Vegetation: an Oscillating Intracardiac mass on the valve or supporting structures, in
the path of regurgitant jets, or on implanted material in the absence of an
alternative anatomical explanation - or an abscess
- Or Pseudoaneurysm
- or New partial dehiscence of a prosthetic valve
- or New valvular regurgitation
- Vegetation: an Oscillating Intracardiac mass on the valve or supporting structures, in
9
Q
Modified Duke Criteria for Endocarditis: Minor
A
- Predisposition: Predisposing Heart Condition or IVDU
- Fever: Temperature ≥38°C(100.4°F)
- Vascular Phenomena: Major Arterial Emboli, Zeptic Pulmonary Infarcts, Mycotic
Aneurysm, Intracranial Haemorrhage, Conjunctival Haemorrhages, Janeway Lesion - Immunological Phenomena: Glomerulonephritis, Oslernodes, Roth Spots, Rheumatoid factor
- Microbiological Evidence: a positive blood culture but not meeting a major criterion as noted earlier, or serological evidence of an active infection with
an organism that can cause infective endocarditisc - Echocardiogram: findings consistent with infective endocarditis but not meeting a major criterion as noted earlier
10
Q
Clinical Fx:
A
- The clinical presentation of IE is dependent on the Organism and the presence of Predisposing Cardiac Conditions.
- Infective Endocarditis may occur as an Acute, Fulminating infection but also as a Chronic or Subacute Illness with Low-Grade Fever and non-specific sx.
- Fever (90%) + Night Sweats → Most common presenting complaint. High temperatures associated with IE (>38 degrees). Ask about previous Viral Prodromal Sx
- Anorexia and Wt. Loss (Quantify the wt. loss
- Myalgia and Arthralgia (Muscle Pain and Joint pain are non specific
- SOB → May have some exceptional Dyspnoea secondary to HF. Indicative of Advanced disease
- A high index of clinical suspicion is required to identify patients with IE and certain criteria should alert the physician
- High clinical suspicion
- New valve lesion/(regurgitant) murmur.
- Embolic event(s) of unknown origin.
- Sepsis of unknown origin.
- Haematuria, glomerulonephritis and suspected renal infarction.
- ‘Fever’ plus:
- Prosthetic material inside the heart
- Other high predisposition for infective endocarditis, e.g. intra-venous drug use
- Newly developed ventricular arrhythmias or conduction dis-turbances
- First manifestation of congestive cardiac failure
- Positive blood cultures (with typical organism)
- Cutaneous (Osler, Janeway) or Ophthalmic (Roth) lesions (Fig.30.90)
- Peripheral abscesses (renal, splenic, spine) of unknown origin
- Predisposition and recent diagnostic/therapeutic interven-tions known to result in significant bacteraemia.
- Low clinical suspicion → Fever plus none of the above.
11
Q
Examination
A
12
Q
Ddx
A
- Sepsis (non-cardiac(
- Cardio-Embolic Disease (AFib, Aortic Arch Thrombus)
- DIC
13
Q
IX
A
- The mainstays of diagnosis of IE are Blood Cultures and ECHO, performed in order to identify the Organism, Ensure Appropriate Therapy and Monitor the patients’s Response to therapy
- Echocardiography is an extremely useful tool if used appropriately but is NOT an appropriate SCREENING test for patients with just a fever or an isolated positive blood culture where there is a low pre-test probability of endocarditis.
- A negative echocardiogram DOES NOT EXCLUDE a diagnosis of endocarditis and TOE and CT-PET may be required, particularly in cases of Suspected Prosthetic Valve infection.
14
Q
Management
A
- The Location of the infection means that Prolonged courses of Antibx are usually required
- The combination of Antibx may be Synergistic in Eradicating Mciorbial Infection and Minimizing Resistance
- BC should be taken prior to Empirical Antibx therapy (but this should not delay therapy in unstable patients)
- Antibx tx should continue for 4-6 weeks
- Typicaly therapeutic Regimens are shown but advice on specific therapy should be sought from the Local Microbiology department according to the organism identified and current sensitivities.
- Serum Levels of Gentamicin and Vancomycin need to be mounted to ensure adequate therapy and prevent Toxicity
- In px with Penicillin Allergy, one of the Glycopeptide Antibiotics, Vancomycin or Teicoplanin, can be sued.
- Penicillins, however are fundamental to the Therapy of Bacterial Endocarditis. Allergies therefore seriously compromise the choice of antibiotcs
- It is essential to confirm the nature of a pettish allergy to ensure the appropriate tx is not withheld needlessly
- Anaphylaxis would be much more ingluential on antibx choice than simplee GI disturbance
15
Q
Regime Choices
A
