Infective Endocarditis Flashcards
1
Q
Organism: Staphylococcus aureus
Virulence Factors: Protein A
A
Function: Binds to the Fc region of antibodies, preventing opsonization and phagocytosis.
2
Q
Organism: Staphylococcus aureus
Virulence Factors: Exotoxins (TSST-1, exfoliative toxins)
A
Function: TSST-1 causes toxic shock syndrome; Exfoliative toxins cause scalded skin syndrome.
3
Q
Organism: Staphylococcus aureus
Key Features:
A
Description: Gram-positive cocci in clusters, Catalase-positive, Coagulase-positive (compared to staph epidermidis which is coagulase-negative), protein A, and lipoteichoic acid
4
Q
Organism: Staphylococcus aureus
Mode of Transmission/Source:
A
Details: Direct contact, skin, nasal carriage.
5
Q
Organism: Staphylococcus aureus
Clinical Presentation (C/P):
A
Conditions: Skin infections (impetigo, abscesses), osteomyelitis, endocarditis, toxic shock syndrome, food poisoning.
6
Q
Organism: Staphylococcus aureus
Treatment:
A
Drugs: MRSA: Vancomycin; MSSA: Nafcillin, Oxacillin.
7
Q
Organism: Staphylococcus epidermidis
Virulence Factors: Biofilm formation
A
Function: Facilitates adhesion to surfaces and protects the bacteria from the immune system and antibiotics
8
Q
Organism: Staphylococcus epidermidis
Virulence Factors: Polysaccharide capsule
A
Function: Protects against phagocytosis and desiccation.
9
Q
Organism: Staphylococcus epidermidis
Key Features:
A
Description: Gram-positive cocci in clusters, Catalase-positive, Coagulase-negative.
10
Q
Organism: Staphylococcus epidermidis
Mode of Transmission/Source:
A
Details: Skin flora, contamination of indwelling devices.
11
Q
Organism: Staphylococcus epidermidis
Clinical Presentation (C/P):
A
Conditions: Infections associated with indwelling medical devices (catheters, prosthetics), bacteremia in immunocompromised patients.
12
Q
Organism: Staphylococcus epidermidis
Treatment:
A
Drugs: Vancomycin for resistant strains, removal of infected devices.
13
Q
Organism: Viridans Streptococci (e.g., S. mutans, S. sanguinis)
Virulence Factors: Adhesins
A
Function: Facilitate adherence to tooth surfaces and heart valves.
14
Q
Organism: Viridans Streptococci (e.g., S. mutans, S. sanguinis)
Virulence Factors: Acid production
A
Function: Contributes to dental caries by demineralizing tooth enamel.
15
Q
Organism: Viridans Streptococci (e.g., S. mutans, S. sanguinis)
Key Features:
A
Description: Alpha-hemolytic, Gram-positive cocci in chains, catalase negative
16
Q
Organism: Viridans Streptococci (e.g., S. mutans, S. sanguinis)
Mode of Transmission/Source:
A
Details: Oral cavity, pharynx, direct inoculation into the bloodstream via dental procedures.
17
Q
Organism: Viridans Streptococci (e.g., S. mutans, S. sanguinis)
Clinical Presentation (C/P):
A
Conditions: Dental caries, subacute bacterial endocarditis.
18
Q
Organism: Viridans Streptococci (e.g., S. mutans, S. sanguinis)
Treatment:
A
Drugs: Penicillin, often combined with gentamicin for endocarditis.
19
Q
Organism: Enterococcus spp.
Virulence Factors: Biofilm formation
A
Function: Helps the bacteria adhere to surfaces and evade the immune system.
20
Q
Organism: Enterococcus spp.
Virulence Factors: Intrinsic antibiotic resistance
A
Function: Naturally resistant to many antibiotics, including cephalosporins.
21
Q
Organism: Enterococcus spp.
Key Features:
A
Description: Gram-positive cocci in pairs/chains, Catalase-negative.
22
Q
Organism: Enterococcus spp.
Mode of Transmission/Source:
A
Details: Colon, lower urinary tract, nosocomial transmission.
23
Q
Organism: Enterococcus spp.
Clinical Presentation (C/P):
A
Conditions: Urinary tract infections, endocarditis, bacteremia, intra-abdominal infections.
24
Q
Organism: Enterococcus spp.
Treatment:
A
Back:
Drugs: Vancomycin, linezolid for resistant strains, Ampicillin for susceptible strains.
25
Organism: Streptococcus gallolyticus (S. bovis, Group D Strep)
Virulence Factors: Capsule
Function: Provides protection against phagocytosis.
26
Organism: Streptococcus gallolyticus (S. bovis, Group D Strep)
Key Features:
Description: Gram-positive cocci in chains, non-hemolytic.
27
Organism: Streptococcus gallolyticus (S. bovis, Group D Strep)
Mode of Transmission/Source:
Details: Colon, lower urinary tract, fecal-oral route, association with gastrointestinal lesions.
28
Organism: Streptococcus gallolyticus (S. bovis, Group D Strep)
Clinical Presentation (C/P):
Conditions: Bacteremia, endocarditis, associated with colorectal cancer.
29
Organism: Streptococcus gallolyticus (S. bovis, Group D Strep)
Treatment:
Drugs: Penicillin, Ceftriaxone.
30
Organism: Pseudomonas aeruginosa
Virulence Factors: Exotoxin A
Function: Inhibits protein synthesis leading to cell death.
31
Organism: Pseudomonas aeruginosa
Virulence Factors: Pyocyanin
Function: Generates reactive oxygen species, causing tissue damage.
32
Organism: Pseudomonas aeruginosa
Key Features:
Description: Gram-negative rod, Oxidase-positive, Non-lactose fermenting, strict aerobes, produces blue-green pigment in cultures
33
Organism: Pseudomonas aeruginosa
Mode of Transmission/Source:
Details: Environment, water sources, hospital-acquired infections.
34
Organism: Pseudomonas aeruginosa
Clinical Presentation (C/P):
Conditions: Pneumonia (especially in CF patients), wound infections, otitis externa, sepsis in immunocompromised individuals.
35
Organism: Pseudomonas aeruginosa
Treatment:
Drugs: Piperacillin-tazobactam, Ceftazidime, Carbapenems, Aminoglycosides.
36
Organism: Fungi (Candida)
Virulence Factors: Adhesins
Function: Facilitate adherence to epithelial and endothelial cells, leading to colonization and infection
37
Organism: Fungi (Candida)
Virulence Factors: Biofilm formation
Function: Protects against antifungal treatment and immune responses.
38
Organism: Fungi (Candida)
Key Features:
Description: Yeast, forms pseudohyphae in tissues.
39
Organism: Fungi (Candida)
Mode of Transmission/Source:
Details: Skin, mucosal surfaces, endogenous flora, overgrowth due to immunosuppression
40
Organism: Fungi (Candida)
Clinical Presentation (C/P):
Conditions: Candidiasis (oral thrush, vulvovaginitis, invasive candidiasis in immunocompromised).
41
Organism: Fungi (Candida)
Treatment:
Drugs: Fluconazole, Amphotericin B for systemic infections.
42
Organism: Fungi (Aspergillus)
Virulence Factors: Production of aflatoxins
Function: Toxins that may lead to liver cancer upon ingestion
43
Organism: Fungi (Aspergillus)
Virulence Factors: Gliotoxin
Function: Suppresses the immune response, aiding in infection persistence.
44
Organism: Fungi (Aspergillus)
Key Features:
Description: Septate hyphae, forms conidia.
45
Organism: Fungi (Aspergillus)
Mode of Transmission/Source:
Details: Inhalation of spores from the environment, respiratory tract dissemination.
46
Organism: Fungi (Aspergillus)
Clinical Presentation (C/P):
Conditions: Pulmonary aspergillosis, allergic bronchopulmonary aspergillosis (ABPA), invasive aspergillosis in immunocompromised hosts.
47
Organism: Fungi (Aspergillus)
Treatment:
Drugs: Voriconazole, Amphotericin B for severe cases.
48
Organism: HACEK Group (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella)
Virulence Factors: Adhesins
Function: Promote adherence to heart valves and endothelial cells, facilitating endocarditis.
49
Organism: HACEK Group (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella)
Virulence Factors: Biofilm formation
Function: Enhances resistance to immune responses and antibiotics.
50
Organism: HACEK Group (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella)
Key Features:
Description: Gram-negative bacilli.coccobacilli, fastidious organisms, part of normal oral flora.
51
Organism: HACEK Group (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella)
Mode of Transmission/Source:
Details: Oral cavity (gingiva), pharynx, human bite wounds.
52
Organism: HACEK Group (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella)
Clinical Presentation (C/P):
Conditions: Subacute bacterial endocarditis, especially in patients with pre-existing valvular disease.
53
Organism: HACEK Group (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella)
Treatment:
Drugs: Ceftriaxone, Ampicillin-sulbactam.
54
Organism: Coxiella burnetii (Q fever)
Virulence Factors: Intracellular survival
Function: Allows the pathogen to persist within host cells, avoiding immune detection.
55
Organism: Coxiella burnetii (Q fever)
Virulence Factors: Resistance to phagolysosomal fusion
Function: Prevents degradation by the host’s immune cells.
56
Organism: Coxiella burnetii (Q fever)
Key Features:
Description: Small Gram-negative, obligate intracellular pathogen.
57
Organism: Coxiella burnetii (Q fever)
Mode of Transmission/Source:
Details: Inhalation of aerosols from infected livestock, unpasteurized dairy products.
58
Organism: Coxiella burnetii (Q fever)
Clinical Presentation (C/P):
Conditions: Acute Q fever: high fever, severe headache, pneumonia; Chronic Q fever: endocarditis, hepatitis.
59
Organism: Coxiella burnetii (Q fever)
Treatment:
Drugs: Doxycycline, Hydroxychloroquine for chronic cases.
60
Bartonella spp. (e.g., B. henselae, B. quintana)
Virulence Factors: Intracellular survival
Function: Allows the bacteria to evade the immune system by residing within host cells.
61
Organism: Bartonella spp. (e.g., B. henselae, B. quintana)
Virulence Factors: Angiogenic factor production
Function: Promotes the growth of new blood vessels, which can contribute to the formation of lesions.
62
Organism: Bartonella spp. (e.g., B. henselae, B. quintana)
Key Features:
Description: Gram-negative rods, fastidious, facultative intracellular pathogens.
63
Organism: Bartonella spp. (e.g., B. henselae, B. quintana)
Mode of Transmission/Source:
Details: B. henselae: Cats/cat fleas; B. quintana: Human body louse, homelessness, poor hygiene.
64
Organism: Bartonella spp. (e.g., B. henselae, B. quintana)
Clinical Presentation (C/P):
Conditions: B. henselae: Cat scratch disease (fever, lymphadenopathy), Bacillary angiomatosis in immunocompromised; B. quintana: Trench fever, bacillary angiomatosis.
65
Organism: Bartonella spp. (e.g., B. henselae, B. quintana)
Treatment:
Drugs: Doxycycline, Azithromycin, or Rifampin.
66
Organism: Brucella spp.
Virulence Factors: Intracellular survival
Function: Allows the bacteria to persist within phagocytes, avoiding immune detection.
67
Organism: Brucella spp.
Virulence Factors: Inhibition of phagosome-lysosome fusion
Function: Prevents the bacteria from being degraded within host immune cells.
68
Organism: Brucella spp.
Key Features:
Description: Small Gram-negative coccobacilli, facultative intracellular.
69
Organism: Brucella spp.
Mode of Transmission/Source:
Details: Unpasteurized dairy products, direct contact with infected livestock.
70
Organism: Brucella spp.
Clinical Presentation (C/P):
Conditions: Undulant fever (recurrent fever, malaise, joint pain
71
Organism: Tropheryma whipplei
Virulence Factors: Intracellular survival
Function: Allows the bacteria to persist within macrophages, evading the immune system and leading to chronic infection.
72
Organism: Tropheryma whipplei
Virulence Factors: Actin polymerization
Function: Facilitates movement within and between host cells, aiding in the spread of the infection.
73
Organism: Tropheryma whipplei
Key Features:
Description: Gram-positive rod, PAS-positive in biopsy, very slow-growing.
74
Organism: Tropheryma whipplei
Mode of Transmission/Source:
Details: Not clearly understood, likely fecal-oral transmission, possible GI tract colonizer.
75
Organism: Tropheryma whipplei
Clinical Presentation (C/P):
Conditions: Malabsorption syndrome (diarrhea, weight loss), arthritis, neurological symptoms (in advanced disease).
76
Organism: Tropheryma whipplei
Treatment:
Drugs: Prolonged antibiotic therapy (e.g., Ceftriaxone followed by Trimethoprim-Sulfamethoxazole).
77
Condition: Prosthetic Valve Endocarditis
Common Pathogens:
Details:
Early Infection (<2 months): Nosocomial pathogens such as Staphylococcus epidermidis, Staphylococcus aureus, Gram-negative bacilli, and Candida.
Late Infection (>2 months): Oral and skin flora such as Staphylococcus epidermidis, Viridans streptococci, and HACEK organisms.
78
Condition: Rheumatic Heart Disease
Pathogenesis:
Details: Cross-reactivity of antibodies against Group A Streptococcus (M protein) with host tissues (heart valves, myocardium) leads to chronic valve damage, particularly mitral valve stenosis and regurgitation.
79
Condition: Viral Myocarditis
Pathogenesis:
Details: Virus infects myocardiocytes, leading to direct cytotoxicity, immune-mediated damage, and inflammation. Can result in cardiac remodeling, dilated cardiomyopathy, and heart failure if chronic.
80
Condition: Pericarditis (Infectious Etiology)
Common Causes:
Details:
Viruses: Coxsackievirus, ECHOvirus, Influenza, Adenovirus, EBV.
Bacteria: Staphylococcus aureus, Streptococcus pneumoniae.
Chronic Causes: Mycobacterium tuberculosis, Fungal infections.
81
Condition: Pericarditis (Infectious Etiology)
Clinical Features:
Symptoms: Fever, sharp pleuritic chest pain, pain alleviated by sitting forward.
Physical Exam: Pericardial friction rub, muffled heart sounds in pericardial effusion, signs of tamponade (e.g., jugular venous distension).
82
Condition: Lyme Disease (Cardiac Involvement)
Stages:
Details:
Stage 1: Erythema migrans ("bullseye" rash), flu-like symptoms.
Stage 2: Carditis, AV block, facial nerve palsy, migratory arthritis.
Stage 3: Chronic arthritis, encephalopathy.
83
Condition: Diphtheria Myocarditis
Pathogenesis:
Details: Diphtheria toxin, produced by Corynebacterium diphtheriae, inhibits protein synthesis via ADP-ribosylation of elongation factor-2, leading to myocarditis, arrhythmias, and circulatory collapse.
84
Condition: Chagas Disease (Cardiac Manifestation)
Features:
Details:
Causative Agent: Trypanosoma cruzi
Vector: Reduviid bug (kissing bug)
Clinical Features: Cardiomegaly, apical left ventricular aneurysm, arrhythmias, right bundle branch block.
85
Laboratory Diagnosis: Infective Endocarditis
Blood Culture:
Details:
Procedure: 3 sets of blood cultures over 24 hours, with at least 1 hour between collections, prior to starting antibiotics.
Culture-Negative IE: Consider organisms like Coxiella burnettii, Bartonella spp., HACEK group, Tropheryma whipplei.
86
Laboratory Diagnosis: Infective Endocarditis
PCR for Diagnosis:
Details: PCR of 16S rRNA can aid in the diagnosis of culture-negative endocarditis, particularly for organisms that do not grow well in culture (e.g., Coxiella burnettii, Bartonella).
87
Condition: Syphilitic Heart Disease
Pathogenesis:
Details: Tertiary syphilis can cause aortitis due to vasculitis of the vasa vasorum, leading to aortic aneurysm and aortic valve regurgitation. The aortic root appears "tree bark" on gross examination.
88
pathogenesis of infective endocarditis (4 steps)
1. Dextran production
2. Surface adhesins-FimA
3. Adherence to specific components of NBTE
4. Glycocalyx & Slime layer
89
Pathogenesis of IE: Initial Trigger
What can lead to mucosal trauma?
Details: Dental manipulations, tonsillectomy, urethral procedures, pulmonary procedures, colon cancer, GI procedures.
90
Pathogenesis of IE: Mucosal Flora
Where does the flora come from that can enter the bloodstream during mucosal trauma?
Details: Flora on mucus membranes or other heavily colonized surfaces.
91
Pathogenesis of IE: Bacteremia
What event follows mucosal trauma and allows bacteria to enter the bloodstream?
Details: Bacteremia occurs when bacteria from the mucosal surfaces enter the bloodstream due to trauma.
92
Pathogenesis of IE: Adherence
How do bacteria adhere to the heart valves in infective endocarditis?
Details: Bacteria adhere to Non-Bacterial Thrombotic Endocarditis (NBTE) via bacterial virulence factors like adhesins (dextran, FimA), fibrin-binding proteins, coagulase, glycocalyx, capsule, enzymes, and toxins.
93
Pathogenesis of IE: Non-Bacterial Thrombotic Endocarditis (NBTE)
What role does NBTE play in the pathogenesis of IE?
Details: NBTE provides a surface on which bacteria can adhere and initiate the infection process, leading to the formation of vegetations on the heart valves.
94
Pathogenesis of IE: Vegetation Formation
What composes the mature vegetation in infective endocarditis?
Details: Mature vegetation consists of platelet-fibrin-bacterial aggregates, formed on the valvular lesion, leading to bacterial division, fibrin deposition, platelet aggregation, extracellular protease production, and protection from neutrophils.
95
Pathogenesis of IE: Valvular Endothelial Injury
What conditions predispose a patient to valvular endothelial injury in IE?
Details: Congenital or acquired heart disease, turbulent blood flow, and other factors can lead to valvular endothelial injury, exposing collagen and tissue factors, which further promotes platelet and fibrin deposition.
96
Pathogenesis of IE: Role of Bacterial Virulence Factors
Which bacterial virulence factors are critical in the pathogenesis of infective endocarditis?
Details: Key virulence factors include adhesins (e.g., dextran, FimA), fibrin-binding proteins, coagulase, glycocalyx, capsule, enzymes, and toxins that promote adherence and vegetation formation.
97
Pathogenesis of IE: Collagen and Tissue Factor Exposure
What triggers platelet and fibrin deposition on heart valves?
Details: Collagen and tissue factor exposure due to valvular endothelial injury leads to platelet and fibrin deposition, forming the basis for vegetation in IE.
98
Pathogenesis of IE: Vegetation Consequences
What are the consequences of vegetation formation in infective endocarditis?
Details: Vegetations can lead to persistent infection, embolic events, and destruction of heart valve structures, contributing to the clinical manifestations of infective endocarditis.
99
frequency of valve involvement in order from greatest to least
mitral > aortic > tricuspid > pulmonary
100
101
Viridans Streptococci is resistant to _____ and ____
bile salts (not lysed by them) and optochin (compared to strep pneumoniae which is sensitive)
102
Enterococcus grows in presence of ____ but tolderates 40% of _____
6.5% sodium chloride; bile
103
enterococcus hydrolyzes ________
esculin
104
how can you differentiate staph from strep
staph is catalase-+ve and strep is catalase -ve
105
how do gram-positive bacteria differ from negative as far as bacterial wall goes
gram-positive has lipoteichoic acid and gram-negative has LPS
106
what is the typical duration of therapy for the treatment of IE
4-8 weeks
107
treatment for acute bacterial endocarditis (NATIVE valve IE)
Vancomycin + cefepime
108
Treatment for subacute bacterial endocarditis (NATIVE valve IE)
vancomycin + ampicillin-sulbactam
109
Treatment for prosthetic valve IE <1 year after valve placement
Vanc + gentamicin +rifampin + cefepime
110
treatment of prosthetic valve IE >1 year after valve placement
Vanc + ceftriaxone
111
streptococcus pyogenes (group A strep) can lead to ______ whereas Streptococcus viridians can lead to _______
RHD/rheumatic fever; IE
112
what kind of disease is RHD
Immune; type II hypersensitivity disease; it will not grow on valves!!!!
113
What is meant by molecular mimicry as it relates to S. pyogens (M protein)
molecular similarity to human myocardium
114
what is the MOA of group A strep (pyogenes) leading to RHD
Person develops sore throat/pharyngitis and due to molecular mimicry of m protein, it can lead to RHD
115
Acute Rheumatic fever vs. Rheumatic heart disease
ARF starts first and can precipitate it's chronic form, RHD as well as mitral stenosis
116
define type II hypersensitivity
Mechanism: IgG or IgM antibodies target antigens on cell surfaces or extracellular matrix, leading to cell destruction via complement activation or antibody-dependent cell-mediated cytotoxicity (ADCC).
Examples: Hemolytic anemia, Goodpasture syndrome, Rh incompatibility.
117
Why can't you culture Strep pyogenes
Its purely immunological and doesn't grow directly on the heart valves
118
diagnostic blood/serum markers for rheumatic fever
anti-DNAse B positive; ASO titer >200 (grown from throat cultures)
119
what is the treatment for acute Rheumatic fever
penicillin (may need prophylaxis to prevent RHD)
120
viruses primarily recruit _______ not _______
lymphocytes not neutrophils
121
__________ are frequent findings in myocarditis
arrhythmias
122
what is the drug of choice for chagas
benznidazole
123
what is the antibiotic to treat lyme disease
doxycycline
124
Rx for pericarditis
aspirin, colchicine
