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MBBS I CPRS > L64 – Infective endocarditis, pericarditis, myocarditis > Flashcards

L64 – Infective endocarditis, pericarditis, myocarditis Flashcards

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1
Q

What is the definition of infective endocarditis?

A

Infection of the endocardial surface of the heart

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2
Q

Definition of Myocarditis?

A

Inflammation of the myocardium

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3
Q

Definition of Pericarditis?

A

Inflammation of the pericardium

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4
Q

Infective endocarditis requires which 2 components?

A

Damaged valve

Microorganism

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5
Q

What are the 3 steps that results in a damage valve necessary for microbe infection?

A

1) Valvular endothelium damage
2) Platelet and fibrin deposition
3) Nonbacterial thrombotic endocarditis (NBTE)

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6
Q

What are the 3 steps of microorganism invasion leading to bacteremia before adhering to heart valve?

A

1) Microbe from muscous membrane or colonized tissue
2) Cause trauma to mucosa or colony tissue
3) Penetrate into blood stream > Bacteremia

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7
Q

What does bacteria in blood stream adhere to to cause infective endocarditis?

A

Bacteria adhere to Nonbacterial thrombic endocarditis valve

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8
Q

Do microbes adhere to healthy heart valves?

A

No

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9
Q

What is the MoA of bacteria after adhering to heart valve?

A

1) Colonization:

2) Mature vegetation

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10
Q

What are some bacterial virulence factors that can cause trauma to mucosa?

A

Bacteriocins (toxins)

IgA Proteases

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11
Q

What are the 3 general factors that can cause valvular endothelium damage?

A

Trauma
Turbulence
Metabolic changes

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12
Q

What processes allow bacteria adhered to heart valve to gain protection from neutrophils?

A
  • Increase bacteria division
  • Increase secretion of extracellular proteases
  • Increase deposition/aggregation of fibrin and platelet
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13
Q

Describe the mature vegetation in IE?

A
  • Dense aggregate of microorganisms
  • Platelet rich thrombus
  • Inflammatory leukocytes
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14
Q

What are some congenital conditions that predisposes to IE?

A

Septal defects
» Atrial / ventricular septal defects

Valvular defects
» Mitral / tricuspid valvular defects

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15
Q

What are some acquired conditions that predispose to IE?

A

 Degenerative

 Rheumatic heart disease

 Prosthetic valve

 Previous endocarditis

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16
Q

List some non-specific, systemic clinical representations of IE?

A 
Fever 
Weight loss 
Malaise 
Night sweat 
Clubbing
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17
Q

Name 2 clinical representations of damaged valve in IE?

A

New/ changing murmur

Heart failure (caused by mitral/ aortic/ tricuspid regurgitation…etc)

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18
Q

What are some Emboli/ metastatic infections caused by IE?

OSSMM

A 
Osteomyelitis 
Spenomagaly/ splenic infarct 
Stroke**
Myocardial infarction 
Mycotic aneurysm
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19
Q

How does IE lead to stroke?

A

Dislodged damaged valve/ vegetation&raquo_space; emboli&raquo_space; stroke

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20
Q

How does IE cause mycotic aneurysm?

A

NOT fungus

Bacteremia infect blood vessels and cause area of vessel weakness > form bulge > aneurysm

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21
Q

Name one immunological complication of IE?

A

Glomerunephritis

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22
Q

Upon physical inspection, what are some classical signs of IE?

A

Janeway’s Lesion
Splinter haemorrhage
Osler nodes
Roth spots

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23
Q

Which of the classical signs of IE are immunological related, which are vascular related?

A

Janeway’s Lesion = vascular phenomenon

Osler’s nodes and Roth’s spots are immunological phenomenon

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24
Q

What are some endogenous origins of infective organisms for IE?

A

Endogenous:
Dental
GI tract
Genito-urinary tract

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25
What are some EXOgenous origins of infective organisms for IE?
``` Skin IV catheters (e.g. drug addict) Cardiovascular devices (e.g. pacemakers) ```
26
What are the 3 most important characteristics of bacteria that causes IE?
- Serum resistance (can survive in blood) - Ability to Adhere to valve surface or platelet-fibrin thrombus - Resist host defense inside vegetation
27
What is THE MOST COMMON pathogen that causes IE on a Native heart valve (not prosthetic)? What is the natural reservoir in humans?
Staphylococcus aureus Skin, thus can enter blood stream via wound on skin
28
Name the 5 classes of pathogens that most commonly cause IE to native heart valves?
``` Staphylococcus Viridans S.Bovis Enterococci Fastidious gram negative bacilli (HACEK) ```
29
What is the most important pathogen to cause IE on prosthetic heart valves?
Coagulase negative Staphylococcus
30
What are the 2 most important Fastidious gram negative bacilli (HACEK) that cause IE on native valves?
Eikenella corrodens Kingella kingae/ Kingella denitrificans
31
How is Eikenella corrodens transmitted to cause IE?
Oral flora into exposed skin wound | e.g. punch someone in the face
32
Kingella kingae/ Kingella denitrificans most commonly affect what age group?
Children
33
What are the 3 pathogens that come from animal contact and can cause IE?
``` Brucella spp. Bartonella henselae (Cat scratch disease) Coxiella burnetti (Q fever) ```
34
What is the most common streptococcus to cause native valve IE?
Viridans streptococci
35
How could colon cancer lead to IE?
Cause normal flora - Strep. Bovis - to enter blood stream
36
Where is coagulase negative Staphylococcus found in body?
Skin normal flora
37
Compare the pathogen that causes early (within 60 days to 12 months) and late prosthetic valve endocarditis?
Early = coagulase-negative Staphylococcus Late = Staph. aureus
38
What is the gold standard/ definitive diagnosis of IE?
- Histology/ culture of vegetation or intracardiac abscess | - Evidence of lesions: vegetation or intracardiac abscess showing active endocarditis on histology
39
What is the clinical criteria for IE?
Duke's criteria Meet 2 major criteria, I major and 3 minor 5 minor
40
What are the 2 major criteria in Duke's criteria for IE? **B& E** in a Mad VIP Fight
Blood cultures positive for IE (proof of bacteremia) Evidence of endocardial involvement (observation of vegetation)
41
What are the minor criteria of Jone's criteria for IE? B& E in a **Mad VIP Fight** MVIPF
- Predisposition (e.g IV use, heart condition) - Fever - Vascular phenomena - Immunological phenomena - Microbiological evidence that do not meet a major criteria
42
List some immunological phenomenon in the minor criteria of Jone's criteria?
``` glomerulonephritis, Osler’s nodes, Roth’s spots, Rheumatoid factor ```
43
list some Vascular phenomenon in the major criteria of Jone's criteria?
mycotic aneurysm, | intracranial hemorrhage, conjunctival hemorrhage, Janeway lesion, MI, stroke, splenic infarct
44
What is considered a blood culture positive result for IE? (2)
Microbes typical in IE are identified from: a) 2 SEPARATE blood cultures b) PERSISTENTLY POSITIVE blood cultures
45
What is the time span for collecting blood to prove persistently positive blood cultures?
2 or more blood cultures drawn at least 12 hours apart Majority (e.g. 3/4) cultures of blood positive
46
Can normal blood culture be used to identify Coxiella burnetii?
Need single blood culture or use IgG antibody titer for *** Q fever Phase 1 antigen *** (>1:800)
47
Is worsening or changing of preexisting murmur a major criteria for Jone's criteria? If not, what should be the correction?
No New valvular regurgitation = major criteria (evidence of endocardial involvement)
48
What are the 3 evidences of endocardial involvement (major criteria) in Jones? CT, echo, regurg
New valvular regurgitation Echocardiogram positive for IE Definitive paravalvular lesions by cardiac CT
49
What features of IE can be seen on echocardiogram?
Intracardial abscess Partial dehiscence (loose) of prosthetic valve Pendulum-like intracardiac mass
50
If the blood culture results are 1 positive and 5 negative, does this contribute to the Jone's Criteria for IE?
Yes As a minor criteria: Positive blood culture but does not meet a major criterion
51
What are the 3 ways to determine causative organism after determining IE?
Culture Serology PCR
52
Serolgy for IE pathogen is used for which two pathogens in particular?
Coxiella burnetii (Q fever) Bartonella henselae (cats)
53
Why is multiple blood cultures required in IE?
To prove continuous bacteraemia
54
Why is skin disinfection necessary before betting blood sample for IE?
remove contamination by skin flora (e.g. coagulase-negative Staphylococcus, Corynebacterium, Bacillus, Propionibacterium acnes)
55
What is the procedure of taking blood sample *for IE suspected*? *which disinfectants, when, how many samples, time between samples, volume of sample*
Iodophore + 70% alcohol Wait at least 1.5 minutes after disinfection, always before taking any antibiotic 3 sets of blood cultures at different sites, at least 1 hour apart 10ml per bottle
56
What is the function of blood culture bottles?
Nutrients, Dilute antibiotics and natural inhibitory factors Prevent clotting Have anaerobic or aerobic bottles
57
2 things not to do when obtaining blood samples?
Change needle prior to inoculating blood culture bottles Draw blood from Intravascular cathether
58
When do you draw blood from intravascular catheter?
Suspect infection is catheter-related
59
What are the 4 causes of Culture negative endocarditis? DANI
1) Prior antibiotics before culture 2) Inadequate blood sample 3) Difficult to grow organism 4) Non-infective cause (e.g. cancer, autoimmunity)
60
List the organisms for IE that are difficult to culture?
HACEK (Fastidious gram negative bacilli e.g. Eikenella corrodens, Kingella Kingae) Brucella Mycoplasma Q fever (Coxiella burnetti)
61
2 options for treating IE?
Antibiotics Surgery
62
Requirements for antiobiotics to treat IE?
Bactericidal, high dose, 4-6 weeks (long duration)
63
Why is IE so hard to treat with antibiotics? | 3 reasons
Bacteria protected from exposure to antibiotics or phagocytes due to BIOFILM Bacteria has redeced cell division High bacteria load inside vegetation
64
Name the antibiotic for Viridans Streptococci?
Penicillin
65
Antibiotic for Methicillin sensitive Staph. aureus?
Cloxacillin
66
Antibiotic for Methicillin resistant Staph. aureus?
Vancomycin
67
Antibiotic for Enterococcus ?
For Ampicillin sensitive enterococci: Ampicillin and Gentamicin or Ampicillin and Ceftriaxone
68
Antibiotic for coagulase negative staph. on prosthetic valves?
Rifampicin | to penetrate biofilm
69
What is the rationale of antibiotic prophylaxis and who is it offered to?
Reduce bacterial load in the blood Offer to patients with: 1) Risk of underlying heart abnormalities 2) Risk of procedure (e.g. surgery is invasive)
70
For antibiotic prophylaxis of IE before procedure/ surgery, what are some principles? - Think choice of antibiotic, dosage, timing and duration* CDDT
Choice: cover most probable organism Duration: cover transient bacteremia Dosage: minimum inhibitory concentration for most probable organism Timing: immediately before procedure
71
What are some underlying heart abnormalities that can increase risk of IE?
MOST IMPORTANT: - Previous IE - Prosthetic valve replacement ``` Others: Mitral valve prolapse Ventricular septal defect Rhuematic heart disease Congenital aortic stenosis ```
72
What is the UK NICE guideline for prophylaxis for IE?
No prophylaxis
73
What are the clinical features of myocarditis?
Chest pain Arrhythmia Congestive HF
74
What are some sources of infection causing myocarditis and pericarditis?
Adjacent organs | Hematogeneous
75
What is the inflammation of myocardium or pericardium due to?
Direct invasion, toxin, or immune mediated
76
What are the top 3 most common viruses that cause Myocarditis?
Enterovirus - EV71, Coxsackie, Echovirus Respiratory virus - Adenovirus, influenza virus Exanthems: mumps, measles, rubella
77
Name 2 bacteria that can cause myocarditis?
Corynbacterium diphtheriae Borrelia burgdoferi (Lyme's disease)
78
Name 3 parasites that can cause Myocarditis?
Trypanosoma cruzi Trichinella spp (wild boar) Toxoplasma gondii (cat, raw beef)
79
Name a fungus that can cause myocarditis?
Dimorphic fungi
80
Aim of myocarditis / pericarditis investigations?
 To confirm the diagnosis of myocarditis / pericarditis  To exclude non-infective cause  For infective cases, to find the etiological organism
81
What are some clinical diagnosis results for myocarditis? *think ECG, echo, blood test*
Increase cardiac enzymes (creatine kinase, troponin) ECG: non-specific changes Echocardiogram: Global abnormality
82
Compare the abnormalities seen in echocardiogram in Myocarditis and IE?
Myocarditis = global abnormality IE = local
83
Myocarditis microbiological diagnosis should be tailoured according to which factors?
according to the patient’s history (e.g. travel, raw food) physical examination investigation result
84
What microbiological test is used to differentially diagnose Myocarditis caused by rheumatic fever??
Rheumatic fever: antistreptolysin O titer (ASOT)
85
What microbiological test is used to differentially diagnose Myocarditis caused by respiratory viruses?
nasopharyngeal aspirate (NPA) >>direct immunofluorescence / PCR
86
What microbiological test is used to differentially diagnose Myocarditis caused by enteroviruses?
throat swab, rectal swab / stool > culture / PCR
87
What microbiological test is used to differentially diagnose Myocarditis caused by respiratory, enteroviruses?
paired serum for serological studies (antibodies)
88
What are the treatment options for myocarditis?
Specific treatment for microorganisms Manage congestive HF Bed rest
89
What are the clinical features of Pericarditis?
Chest pain (worse when breathing, swallowing or supine) Pericardial rub and effusion Cardiac tamponade
90
What are the viruses that can cause Pericarditis?
Very similar to myocarditis Respiratory viruses Enteroviruses Exanthems
91
What are some bacteria and other pathogens that can commonly cause pericarditis?
 Gram-positive: Staphylococcus aureus, Streptococcus  Gram-negative: Enterobacteriaceae, Haemophilus influenzae, Neisseria meningiditis  Fungi (especially dimorphic)  Parasites
92
What are the clinical exam results for pericarditis?
ECG: Diffuse ST elevation (concave up) Echo: normal (unless pericardial effusion is involved)
93
What are the gold standard tests for pericarditis?
Pericardial biopsy | Pericardiocentesis
94
What are the similarities and differences between the treatment of pericarditis and myocarditis?
Similar : Both need bed rest, specific treatment for microbes Difference: -Myocarditis need management of congestive HF -Pericarditis need NSAID and Drainage of pericardial fluid/ Pericardectomy

MBBS I CPRS (78 decks)

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