Infective Endocarditis Flashcards
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
- VSD
- 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
- AIDS
- 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
Antibiotics: - 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
- MSSA
- MRSA
- 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
- PVE
- IVDA
- 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
