Infective Endocarditis Flashcards Preview

Cardiovascular System > Infective Endocarditis > Flashcards

Flashcards in Infective Endocarditis Deck (55):

Where can infective endocarditis occur?

- Infection of the inner layer of heart: endocardium
- Heart valves: native, prosthetic
- Interventricular septum: septal defect
- Chordae tendinae
- Intra-cardiac devices


Prognosis and mortality of Infective Endocarditis

- Poor prognosis
- High mortality

Neither incidence nor mortality have decreased in the past 30 years


Incidence features of Infective Endocarditis

- Males have it more than females = >2:1
- Females have a worse prognosis
- Around 25%, no underlying structural heart disease


Cardiac risk factors for Infective Endocarditis (from most common to least)

- Surgery for prosthetic IE
- Prior native IE
- Cardiac surgery for native IE
- Prosthetic heart valve
- Rheumatic heart disease
- Aortic stenosis
- MVP, with mitral regurgitation
- MVP, no murmur


Specific predisposing valvular lesions in patients with IE

Native valve disease
- Mitral regurgitation
- Aortic regurgitation
- Aortic stenosis
- Congenital heart disease

Prosthetic valve


Non-cardiac risk factors for IE

- Injection drug usage
- Indwelling medical devices
- Diabetes mellitus
- Chronic skin infections, burns
- Alcoholic cirrhosis
- Gastrointenstinal lesions
- Solid organ transplant
- Homeless, body lice
- Pneumonia, meningitis
- Contact with containerised milk or infected farm animals
- Dog/cat exposure


Pathophysiology of infective endocarditis

- Adherence + invasion of non-bacterial thrombotic endocarditis = a sterile fibrin-platelet vegetation
- Mechanical distruption of valve endothelium!
- Physically normal endothelium - 25% : local inflammation


Classification of acute bacteraemia

- Fulminant illness over days/weeks
- Staph aureus


Classification of subacute bacteraemia

- Weeks/months
- Streptococci


Classification of localisation/intracardiac material

- Left-sided native valve
- Left-sided prosthetic valve: late >1 year after surgery
- Right-sided
- Device related: PPM, ICD, acute/subacute/chronic, localisation/intracardiac material


Mode of acquisition of Infective Endocarditis

- Health care-related: nosocomial/idiopathic, non-nosocomial
- Community-acquired
- IVDA (intravenous drug abusers)


Features of diagnosis of Infective Endocarditis

- Variable presentation
- High index of suspicion
- Bacteraemic episode
- Non-specific sumptoms: fever, fatigue, malaise


Symptoms of Infective Endocarditis

- Fever
- Weight loss
- Headache
- Musculoskeletal pain
- Altered mentation
- Murmur


Clinical findings of Infective Endocarditis

Peripheral stigmata
- Petechiae
- Janeway lesions
- Osler's nodes
- Splinter haemorhages
- Clubbing

- Neurological manifestations
- Roth's spots
- Splenomegaly or infarct


Signs of Infective Endocarditis

- Congestive cardiac failure

- Embolic phenomena: focal neurological signs, peripheral embolus/ abscess-30%, pulmonary embolus/abscess

- Vascular/immunological phenomena


Vascular/Immunological phenomena signs

Immune complex deposition
- Splinter haemorrhages
- Vasculitic rash
- Roth spots
- Osler's nodes
- Janeway lesions
- Nephritis


Features of blood cultures in IE

- Prior to starting antibiotics
- 3 sets
- Different sites
- >6 hours between

- Severe sepsis: 2 sets, different sites, within 1 hour


Features of Urinalysis in IE

Positive blood


Features of ECG in IE

Conduction delay


Features of chest X-ray in IE

- Heart failure
- Pulmonary abscesses


Features of Echocardiogram in IE

- Transthoracic (TTE)
- +/- transoesophageal (TOE)


Types of microbiology blood cultures in IE

- IE with +ve blood cultures
- IE with -ve blood cultures: prior antibx Rx
- IE with -ve blood cultures: fastidious organisms
- IE with -ve blood cultures: intracellular bacteria


What blood culture is most common in IE?

IE with +ve blood cultures
- 85% of all IE
- Streptococci
- Enterococci
- Staphylococcus


Types of streptococci in +ve blood cultures

- Oral (viridans) streptococci: S.sanguis, S.mitis, S. salivarius, S. mutans, Germella morbillorum

- S. milleri, S. anginosus group (S.anginosus, S. intermedius, S. constellatus)

- Nutritionally variant 'defective' streptococci recently reclassified: Abiotrophia, Granulicatella

- Group D streptococci: associated with GI tract, streptococcus bovis/equinus complex


Types of Enterococci in +ve blood cultures

- E. faecalis
- E. faecium
- E. durans


Types of Staphylococcus in +ve blood cultures

- S.aureus: health care associated IE

- Coagulase-negative staph (CNS), S.epidermidis: health care-associated IE


Types of -ve blood cultures in IE

- Prior antibiotic treatment
- Fastidious organisms
- Intracellular bacteria


Features of prior antibiotic treatment in -ve blood cultures

- Antibiotics given for unexplained fever
- Before blood cultures taken
- Diagnosis of IE not been considered
- Blood cultures may remain negative for many days after discontinuation of antibiotics
- Causative organisms most likely: oral streptococcus,CNS


Fastidious organisms in -ve blood cultures

- Nutritionally variant streptococci
- Fastidious gram -ve bacilli ]: HACEK group
- Brucella
- Fungi


Features of intracellular bacteria in -ve blood cultures

5% of all IE
- Coxiella burnetii
- Bartonella
- Chlamydia

- Serological testing, cell culture, gene amplification, PCR


What is the major criteria for Modified Duke Criteria?

- Identifying organism
- Providing evidence of infection anywhere within the heart


What is the minor criteria for Modified Duke Criteria?

Focus on the endocarditis complex of clinical findings


Features of major criteria in Modified Duke Criteria

Blood cultures positive for IE
- Typical organism consistent with IE from 2 separate blood cultures
- Organisms consistent with IE from persistently positive blood cultures
- Single +ve blood culture for Coxiella burnetii

Evidence of endocardial involvement
- Positive echocardiogram
- New valvular regurgitation/murmur


Features of minor criteria in Modified Duke Criteria

- Predisposition
- Fever: >38 degrees celsius
- Vascular phenomena
- Immunologic phenomena
- Microbiological evidence


Features of vascular phenomena in minor criteria in Modified Duke Criteria

- Major arterial emboli
- Septic pulmonary infarcts
- Mycotic aneurysm
- Intracerebral haemorrhages
- Conjunctival haemorrhages
- Janeway lesions


Features of immunologic phenomena in minor criteria in Modified Duke Criteria

- Glomerulonephritis
- Osler's nodes
- Roth spots
- Rheumatoid fever


Features of microbiological evidence in minor criteria in Modified Duke Criteria

- Positive blood cultures: do not meet minor criterion (check)
- Serological evidence of active infection with organism consistent with IE


Treatment for IE

- Surgery
- Aminoglycosides (synergise with cell wall inhibitors)
- IV gentamicin + IV amoxicillin (native valves)
- Gentamicin + vancomycin (native


Infection organisms of native valves

- Staphylococci
- Streptococci
- HACEK species
- Bartonella species


infection organisms of prosthetic valves

- non-HACEK G -ve pathogens


Treatment for subacute/chronic native valves

- IV Gentamicin
- IV Benzylpenicilllin
- or IV Amoxycillin


Treatment for acute native valves

- IV Gentamicin
- IV Flucloxacillin


Treatment for prosthetic valves

- Gentamicin
- IV Vancomycin
- +Rifampicin


How is treatment decided?

- Blood culture positive
- Antibiotics choice dictated by: micro-organism isolated, Sensitivities, Resistance
- Close liason with: microbiologist, pharmacist


What checks should be performed for continuing treatment?

- Daily: FBC, U+E's, CRP
- ECG: 1-2 days
- Echo: weekly


Fungi in IE

- Immunocompromised

- Candida
- Aspergillus
- Very high mortality >50%
- Rx: dual anti-fungals, valve replacement, often maintained long term, sometimes for life


Complications of Infected Endocarditis/ indications for surgery

- Heart failure
- Fistula formation
- Leaflet perforation
- Uncontrolled infection
- Abscess formation
- Atrioventricular heart block
- Embolism
- Prosthetic valve dysfunction/dehiscence


Other indications for surgery

- Uncontrolled infection
- Enlarging vegetation
- Abscess formation
- Atrioventricular block


What is the most severe form of IE?

PVE (Prosthetic valve endocarditis)

- Prevalence: 1-6% of valve prosthesis
- 10-30% of all cases of IE


What is PVE(prosthetic valve endocarditis) associated with?

- Difficulties in diagnosis
- Difficulty with optimal therapeutic strategy
- Poor prognosis (20-40% in-hospital mortality)
- Removal of prosthetic material


Features of medical therapy for intracardiac devices

- Medical therapy alone associated with: high mortality, risk of recurrence
- Removal recommended: proven cases, considered in suspected cases
- Prolonged antibiotic course: IV antibiotics for as long as possible prior to removal, 'sterilise' device/prosthesis


Features of Prophylaxis in IE

- Existing evidence does not support the extensive use of antibiotic prophylaxis recommended in previous guidelines

- Prophylaxis should be limited to highest risk patients: highest incidence of IE, highest risk of adverse outcomes from IE

- Indication for antibiotic prophylaxis should be reduced compared to previous recommendations

- Good oral hygiene & regular dental review are of particular importance


What are cardiac conditions at highest risk of IE?

- Acquired valvular disease: stenosis, regurgitation
- Valve replacement
- Structural congenital heart disease
- Hypertrophic cardiomyopathy
- Previous IE


When is it okay to offer prophylaxis?

- An antibiotic that covers organisms that cause IE
- If a person at risk of IE
- Is receiving antimicrobial therapy
- Due to undergoing a GI or GU procedure
- At a site where there is suspected infection


When is it not okay to offer prophylaxis?

- Dental procedures
- Non-dental procedures: upper/lower GI tract, genitourinary tract, upper/lower respiratory tract: ENT, throat procedures, bronchoscopy