Infective Endocarditis

Question 1

What is IE?

Answer 1

Infection or colonization of endocardium , heart valves , congenital defects by bacteria , rickettsiae , fungi
- Often characterised by a low grade persistent bacteraemia

Question 2

What causes high mortality?

Answer 2

1. Virulence of organism or severe infection
2. Presence of underlying disease
3. Elderly
4. Inadequate treatment

Question 3

Poor prognostic facrors?

Answer 3

1. Candida infection
2. Staphylococcus aureus infection
3. Gram-negative organisms
4. Prosthetic valve (especially ‘early’, acquired during surgery)
5. Culture negative endocarditis
6. Low complement levels

Question 4

Mortality according to organism?

Answer 4

Staphylococci - 30%
Bowel organisms - 15%
Streptococci - 5%

Question 5

Host local factors that increase susceptibility to IE?

Answer 5

1. CONGENITAL OR RHEUMATIC HEART DISEASE
2. PROSTHETIC HEART VALVES
3. HEART SURGERY

Question 6

General factors increasing susceptibility?

Answer 6

underlying disease
e.g. DM

Question 7

Drugs that increase susceptibility?

Answer 7

1. IATROGENIC:
   IMMUNOSUPPRESSIVE TREATMENT
   CYTOTOXIC AGENTS
2. SELF- INFLICTED
   ALCOHOLISM
   ADDICTION (INJECTED DRUGS )

Question 8

Protective factors?

Answer 8

antimicrobial chemotherapy

Question 9

Formation of vegetations?

Answer 9

1. Fibrin, platelets (thrombi), bacteria colonies attach to heart valves
2. Break off infected emboli and travel to distant organs
   e.g. kidney , brain
3. Immune complex formation causes glomerular damage e.g. haematuria
4. Valves infection leads to destruction and subsequent heart failure
5. Drug addicts > tricuspid, pulmonary valves of right side of heart causing lung emboli and pneumonia

Question 10

Pathology?

Answer 10

1. Emboli can break off vegetations causing abscesses at distant sites where they lodge leading to sequelae such as septic infarcts or mycotic aneurysms
2. Vegetations of subacute endocarditis are associated with less valvular destruction than acute endocarditis
3. Gram +ve bacteria are particularly resistant to patient’s innate antibacterial activity (eg complement) which facilitates the adhesion & formation of vegetations

Question 11

Sources of infection?

Answer 11

1. Dental extraction and other dental procedures
2. Cardiac surgery ( prosthetic valves)
3. Intravenous medication
4. Iv. Drug addiction
5. Intracardiac or intravenous catheters
6. Obstetric or gynaecologic procedures

Question 12

Portal of entry?

Answer 12

1. Dental, extraction bleeding bacteremia
   - Rocking the tooth in the socket pumping effect on the vessels of periodontal ligament, forces bacteria from gingival pockets into blood stream
2. oral irrigation device

Question 13

Pathogenesis of IE?

Which pathogens cause IE?

Answer 13

1. staph aureus
2. strep viridans
3. coag -ve staph
4. enterococci
5. HACEK group

Question 14

Staph aureus pathogenesis?

Answer 14

1. MSSA is more frequent in community-acquired IE, infects mainly native valves & is associated with bacteraemia of unknown origin
2. MRSA is more related to nosocomial infection, wound infection, permanent IV catheters or surgery in previous 6/12

Question 15

Coag. negative staph causes?

Answer 15

prosthetic valve endocarditis
esp. within first 6-12/12 after valve surgery
N.B: MRSA is more common

Question 16

HACEK group?

Answer 16

1. Haemophilus group
2. Actinobacillus group
3. Cardiobacterium hominis
4. Eikenella corrodens
5. Kingella kingae

Question 17

Fungal causes of IE?

Answer 17

candida and aspergillus

Question 18

Whos is most likely to have fungal IE?

Answer 18

Patients with:
1. IVDU
2. prosthetic valve
3. long-term CVC
- needs to be considered in presence of bulky vegetations, metastatic infection, perivalvular invasion, or embolisation to large blood vessels despite -ve BC

Question 19

What organisms to suspect if BC is negative?

Answer 19

1. Coxiella burnetti
2. Legionella spp
3. Brucella spp
4. Bartonella spp
5. Chlamydiae spp
6. HACEK
7. OR prior antibiotic use

Question 20

The most common factors predisposing to IE?

Answer 20

are those that cause bacteraemia
1. Dental/surgical procedures
2. Needle sharing amongst IVDU
3. Breaks in skin

Question 21

Classification of IE based on etiology?

Answer 21

1. Native Valve IE
2. Prosthetic Valve IE
3. Intravenous drug abuse (IVDA) IE
4. Nosocomial IE

Question 22

Classification of IE based on duration?

Answer 22

1. acute
2. subacute

Question 23

Acute IE?

Answer 23

• Infection of previously normal heart valve by a highly virulent organism that produces necrotising, ulcerative, destructive lesions
• Difficult to cure with Abx & usually require Sx
• Death can occur within days to weeks despite Rx

Question 24

Subacute IE?

Answer 24

• Organisms are usually of lower virulence
• Cause insidious infections of deformed (native) valves that are less destructive
• Can take prolonged course: weeks to months
• More amenable to treatment with antibiotics

Question 25

Clinical features?

Answer 25

1. Onset is insidious ( SBE) – 3 weeks after extraction 2. Fever ( mild and prolonged ), chills and sweating 3. Malaise , weight loss , weakness 4. Changing murmurs 5. Anaemia , leucocytosis 6. Microscopic haematuria 7. Petechiae 8. Splenomegaly 9. Splinter haemorrhage 10. Finger clubbing

Question 26

Complications?

Answer 26

In IVDU right sided IE usually affect the tricuspid valve & occasionally the pulmonary valve, instead of systemic issues pulmonary embolism is the most important complication which can evolve into Pulmonary infarction Pulmonary abscess Bilateral pneumothoraces Pleural effusion Empyema

Question 27

Diagnosis?

Answer 27

The dx is confirmed in presence of 2 major criteria, 1 major + 2 minor or 5 minor criteria IE considered in presence of 1 major + 1 minor or 3 minor

Question 28

Lab diagnosis?

Answer 28

1. serial blood culture ( 2-3 sets before antibiotic therapy ) - Aerobic - Anaerobic - CBC, ESR and CRP, Complement levels (C3, C4, CH50) - RF - Urinalysis 1. serological tests CFT ( coxiella burniti ) 1. sensitivity test

Question 29

Blood for culture contaminated by normal skin flora?

Answer 29

1. Staphylococcus epidermidis 2. Diphtheriods 3. Propioniobacteria (anaerobic diphtheroides)

Question 30

Avoiding contamination of blood culture by normal flora?

Answer 30

So first clean the site (mainly anticubital fossa) with: 1. alcohol 70% and leave for 1-11/2 minutes) 2. cholorhexidine 3. iodine

Question 31

Major criteria?

Answer 31

1. Blood culture positive for IE - typical microorganisms consistent with IE from 2 separate blood cultures e.g. viridans streptococci, HACEK, staphylococcus aureus - at least 2 positive cultures of blood samples >12h apart - 4 cultures with at least first and last sample drawn at least 1 hr apart 2. Endocardial involvement 3. Echocardiogram positive for IE 4. New valvular regurgitation

Question 32

Minor criteria?

Answer 32

1. Predisposition, predisposing heart condition or injection drug use 2. Fever >38 degrees 3. Vascular phenomena 4. Immunologic phenomena 5. Microbiological evidence

Question 33

Petechiae?

Answer 33

Nonspecific Often located on extremities or mucous membranes

Question 34

Radiology investigatioms?

Answer 34

Chest x-ray Look for multiple focal infiltrates and calcification of heart valves ECG Rarely diagnostic Look for evidence of ischemia, conduction delay, and arrhythmias Echocardiography

Question 35

Cardiac complications?

Answer 35

Heart failure Extensive valvular damage Paravalvular abscess (30-40%) Most common in aortic valve, IVDA, and S. aureus May extend into adjacent conduction tissue causing arrythmias Higher rates of embolization and mortality Pericarditis Fistulous intracardiac connections

Question 36

Embolic complications?

Answer 36

Stroke Myocardial Infarction Fragments of valvular vegetation or vegetation-induced stenosis of coronary ostia Ischemic limbs Hypoxia from pulmonary emboli Abdominal pain (splenic or renal infarction)

Question 37

Metastatic spread of infection?

Answer 37

Metastatic abscess Kidneys, spleen, brain, soft tissues Meningitis and/or encephalitis Vertebral osteomyelitis Septic arthritis

Question 38

Criteria for antibiotic treatment?

Answer 38

Bactericidal Parenteral High dose Prolonged

Question 39

Viridans streptococci?

Answer 39

Benzyl penicillin I.V. 4 MU every 4 hrs for 4 weeks or If penicillin allergy: vancomycin + low dose gentamicin

Question 40

Streptococcus faecalis?

Answer 40

ampicillin + gentamicin I.V

Question 41

Native valve endocarditis caused by staphylococci?

Answer 41

Flucloxacillin If penicillin allergic or MRSA: vancomycin + rifampicin

Question 42

Prosthetic valve endocarditis caused by staphylococci?

Answer 42

Flucloxacillin + rifampicin + low-dose gentamicin If penicillin allergic or MRSA: vancomycin + rifampicin + low-dose gentamicin

Question 43

Recurrence after cure is common in?

Answer 43

Drug addicts Immunodeficient patients

Question 44

Antibiotic prophylaxis is recommended in?

Answer 44

high risk patients Acquired valvular HD Previous valve replacement Structural congenital HD (excluding repaired ASD, VSD or PDA)

Question 45

Indications for surgery?

Answer 45

Severe valvular incompetence/large vegetations Aortic abscess (often indicated by a lengthening PR interval) (9-14%) Infections resistant to antibiotics/fungal infections (9-11%) Cardiac failure refractory to standard medical treatment Recurrent emboli after antibiotic therapy

Question 46

Complications of surgery?

Answer 46

Persistent septic shock Coagulopathy Acute renal failure Stroke Refractory heart failure Conduction abnormalities