Flashcards in L64 – Infective endocarditis, pericarditis, myocarditis Deck (94):
What is the definition of infective endocarditis?
Infection of the endocardial surface of the heart
Definition of Myocarditis?
Inflammation of the myocardium
Definition of Pericarditis?
Inflammation of the pericardium
Infective endocarditis requires which 2 components?
What are the 3 steps that results in a damage valve necessary for microbe infection?
1) Valvular endothelium damage
2) Platelet and fibrin deposition
3) Nonbacterial thrombotic endocarditis (NBTE)
What are the 3 steps of microorganism invasion leading to bacteremia before adhering to heart valve?
1) Microbe from muscous membrane or colonized tissue
2) Cause trauma to mucosa or colony tissue
3) Penetrate into blood stream > Bacteremia
What does bacteria in blood stream adhere to to cause infective endocarditis?
Bacteria adhere to Nonbacterial thrombic endocarditis valve
Do microbes adhere to healthy heart valves?
What is the MoA of bacteria after adhering to heart valve?
2) Mature vegetation
What are some bacterial virulence factors that can cause trauma to mucosa?
What are the 3 general factors that can cause valvular endothelium damage?
What processes allow bacteria adhered to heart valve to gain protection from neutrophils?
- Increase bacteria division
- Increase secretion of extracellular proteases
- Increase deposition/aggregation of fibrin and platelet
Describe the mature vegetation in IE?
-Dense aggregate of microorganisms
-Platelet rich thrombus
What are some congenital conditions that predisposes to IE?
>> Atrial / ventricular septal defects
>> Mitral / tricuspid valvular defects
What are some acquired conditions that predispose to IE?
Rheumatic heart disease
List some non-specific, systemic clinical representations of IE?
Name 2 clinical representations of damaged valve in IE?
New/ changing murmur
Heart failure (caused by mitral/ aortic/ tricuspid regurgitation...etc)
What are some Emboli/ metastatic infections caused by IE?
Spenomagaly/ splenic infarct
How does IE lead to stroke?
Dislodged damaged valve/ vegetation >> emboli >> stroke
How does IE cause mycotic aneurysm?
Bacteremia infect blood vessels and cause area of vessel weakness > form bulge > aneurysm
Name one immunological complication of IE?
Upon physical inspection, what are some classical signs of IE?
Which of the classical signs of IE are immunological related, which are vascular related?
Janeway's Lesion = vascular phenomenon
Osler's nodes and Roth's spots are immunological phenomenon
What are some endogenous origins of infective organisms for IE?
What are some EXOgenous origins of infective organisms for IE?
IV catheters (e.g. drug addict)
Cardiovascular devices (e.g. pacemakers)
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
What is THE MOST COMMON pathogen that causes IE on a Native heart valve (not prosthetic)? What is the natural reservoir in humans?
Skin, thus can enter blood stream via wound on skin
Name the 5 classes of pathogens that most commonly cause IE to native heart valves?
Fastidious gram negative bacilli (HACEK)
What is the most important pathogen to cause IE on prosthetic heart valves?
Coagulase negative Staphylococcus
What are the 2 most important Fastidious gram negative bacilli (HACEK) that cause IE on native valves?
Kingella kingae/ Kingella denitrificans
How is Eikenella corrodens transmitted to cause IE?
Oral flora into exposed skin wound
(e.g. punch someone in the face )
Kingella kingae/ Kingella denitrificans most commonly affect what age group?
What are the 3 pathogens that come from animal contact and can cause IE?
Bartonella henselae (Cat scratch disease)
Coxiella burnetti (Q fever)
What is the most common streptococcus to cause native valve IE?
How could colon cancer lead to IE?
Cause normal flora - Strep. Bovis - to enter blood stream
Where is coagulase negative Staphylococcus found in body?
Skin normal flora
Compare the pathogen that causes early (within 60 days to 12 months) and late prosthetic valve endocarditis?
Early = coagulase-negative Staphylococcus
Late = Staph. aureus
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
What is the clinical criteria for IE?
Meet 2 major criteria,
I major and 3 minor
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)
What are the minor criteria of Jone's criteria for IE?
B& E in a **Mad VIP Fight**
-Predisposition (e.g IV use, heart condition)
-Microbiological evidence that do not meet a major criteria
List some immunological phenomenon in the minor criteria of Jone's criteria?
list some Vascular phenomenon in the major criteria of Jone's criteria?
intracranial hemorrhage, conjunctival hemorrhage, Janeway lesion, MI, stroke, splenic infarct
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
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
Can normal blood culture be used to identify Coxiella burnetii?
Need single blood culture
use IgG antibody titer for *** Q fever Phase 1 antigen *** (>1:800)
Is worsening or changing of preexisting murmur a major criteria for Jone's criteria? If not, what should be the correction?
New valvular regurgitation = major criteria
(evidence of endocardial involvement)
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
What features of IE can be seen on echocardiogram?
Partial dehiscence (loose) of prosthetic valve
Pendulum-like intracardiac mass
If the blood culture results are 1 positive and 5 negative, does this contribute to the Jone's Criteria for IE?
As a minor criteria: Positive blood culture but does not meet a major criterion
What are the 3 ways to determine causative organism after determining IE?
Serolgy for IE pathogen is used for which two pathogens in particular?
Coxiella burnetii (Q fever)
Bartonella henselae (cats)
Why is multiple blood cultures required in IE?
To prove continuous bacteraemia
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)
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
What is the function of blood culture bottles?
Nutrients, Dilute antibiotics and natural inhibitory factors
Have anaerobic or aerobic bottles
2 things not to do when obtaining blood samples?
Change needle prior to inoculating blood culture bottles
Draw blood from Intravascular cathether
When do you draw blood from intravascular catheter?
Suspect infection is catheter-related
What are the 4 causes of Culture negative endocarditis?
1) Prior antibiotics before culture
2) Inadequate blood sample
3) Difficult to grow organism
4) Non-infective cause (e.g. cancer, autoimmunity)
List the organisms for IE that are difficult to culture?
HACEK (Fastidious gram negative bacilli e.g. Eikenella corrodens, Kingella Kingae)
Q fever (Coxiella burnetti)
2 options for treating IE?
Requirements for antiobiotics to treat IE?
Bactericidal, high dose, 4-6 weeks (long duration)
Why is IE so hard to treat with antibiotics?
Bacteria protected from exposure to antibiotics or phagocytes due to BIOFILM
Bacteria has redeced cell division
High bacteria load inside vegetation
Name the antibiotic for Viridans Streptococci?
Antibiotic for Methicillin sensitive Staph. aureus?
Antibiotic for Methicillin resistant Staph. aureus?
Antibiotic for Enterococcus ?
For Ampicillin sensitive enterococci:
Ampicillin and Gentamicin
Ampicillin and Ceftriaxone
Antibiotic for coagulase negative staph. on prosthetic valves?
(to penetrate biofilm)
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)
For antibiotic prophylaxis of IE before procedure/ surgery, what are some principles?
- Think choice of antibiotic, dosage, timing and duration*
Choice: cover most probable organism
Duration: cover transient bacteremia
Dosage: minimum inhibitory concentration for most probable organism
Timing: immediately before procedure
What are some underlying heart abnormalities that can increase risk of IE?
-Prosthetic valve replacement
Mitral valve prolapse
Ventricular septal defect
Rhuematic heart disease
Congenital aortic stenosis
What is the UK NICE guideline for prophylaxis for IE?
What are the clinical features of myocarditis?
What are some sources of infection causing myocarditis and pericarditis?
What is the inflammation of myocardium or pericardium due to?
Direct invasion, toxin, or immune mediated
What are the top 3 most common viruses that cause Myocarditis?
Enterovirus - EV71, Coxsackie, Echovirus
Respiratory virus - Adenovirus, influenza virus
Exanthems: mumps, measles, rubella
Name 2 bacteria that can cause myocarditis?
Borrelia burgdoferi (Lyme's disease)
Name 3 parasites that can cause Myocarditis?
Trichinella spp (wild boar)
Toxoplasma gondii (cat, raw beef)
Name a fungus that can cause myocarditis?
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
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
Compare the abnormalities seen in echocardiogram in Myocarditis and IE?
Myocarditis = global abnormality
IE = local
Myocarditis microbiological diagnosis should be tailoured according to which factors?
according to the patient’s history (e.g. travel, raw food)
What microbiological test is used to differentially diagnose Myocarditis caused by rheumatic fever??
Rheumatic fever: antistreptolysin O titer (ASOT)
What microbiological test is used to differentially diagnose Myocarditis caused by respiratory viruses?
nasopharyngeal aspirate (NPA)
>>direct immunofluorescence / PCR
What microbiological test is used to differentially diagnose Myocarditis caused by enteroviruses?
throat swab, rectal swab / stool > culture / PCR
What microbiological test is used to differentially diagnose Myocarditis caused by respiratory, enteroviruses?
paired serum for serological studies (antibodies)
What are the treatment options for myocarditis?
Specific treatment for microorganisms
Manage congestive HF
What are the clinical features of Pericarditis?
Chest pain (worse when breathing, swallowing or supine)
Pericardial rub and effusion
What are the viruses that can cause Pericarditis?
Very similar to myocarditis
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)
What are the clinical exam results for pericarditis?
ECG: Diffuse ST elevation (concave up)
Echo: normal (unless pericardial effusion is involved)
What are the gold standard tests for pericarditis?