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CVM Exam 2 > Lecture 1: Microbiology of the Cardiovascular System > Flashcards

Lecture 1: Microbiology of the Cardiovascular System Flashcards

1
Q

What are 6 differential diagnoses for Myocarditis?

A
  1. Acute MI
  2. Acute and/or chronic HF
  3. Atypical chest pain
  4. Pericarditis
  5. Cardiomyopathies
  6. Valvular disease
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2
Q

During PE/ausculation of patient with myocarditis what are 3 possible findings?

A
  1. Soft S3/S4 (impaired ventricular function)
  2. New murmur (2’ to valvular insufficiency - variable)
  3. Pericardial friction rub (if extension into pericardium)
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3
Q

With myocarditis the signs and sx’s will be similar to CHF of which part of h cardiac cycle?

What signs/sx’s?

A
  • Systolic CHF (decreased contractility)
  • Orthopnea, dyspnea on exertions, crackles, paroxysmal noctural dyspnea
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4
Q

Upon extra-workup for myocarditis utilizing an EKG what are you assessing for and what are the most common findings?

Which rhythm is most common?

A
  • A assess for arrhythmia (sinus TACHY most common)
  • Transient ST-T wave
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5
Q

What are 5 workups that should be considered to aid in your diangosis of myocarditis?

A
  1. EKG
  2. CXR
  3. Echocardiogram
  4. PCR - detection of viral genome
  5. Labs
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6
Q

What would an echocardiogram help you assess in a patients with suspected myocarditis?

A
  • Ventricular function and structure
  • Evaluation of ejection fraction, LV size, and wall abnormalities
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7
Q

Which 5 lab values would be helpful in the diagnosis of myocarditis?

A
  1. CBC (possible leukocytosis)
  2. Cardiac enzymes (likely ↑ 2’ to myocyte damage)
  3. BNP (signs/sx’s of HF)
  4. CPK (assesing muscle damage)
  5. ESR and CRP
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8
Q

Which invasive diagnostic study may aid in the definitive diagnosis of Myocarditis?

A

Endomyocardial biopsy

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9
Q

What are 3 possible complications of myocarditis?

A
  1. Dilated cardiomyopathy
  2. Myopericarditis
  3. Sudden cardiac death (20%)
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10
Q

Which 3 drug classes are feasible options for treating myocarditis?

A
  • Beta blockers
  • ACE-I
  • Diuretics
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11
Q

What are 3 things that need to be avoided or reduced in a patient with myocarditis?

A
  • NSAIDs and Alcohol
  • Exercise (restricted)
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12
Q

What are the 3 most common infectious etiologies of Myocarditis?

A
  • Coxsackie B
  • Trypanosoma cruzi
  • Trichinella spiralis
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13
Q

Which viral family does Coxsackie B virus belong to and what is it’s morphology?

A
  • Picornaviridae, Enterovirus
  • (+) ssRNA virus, small, naked, icosahedral
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14
Q

When is the peak incidence of Coxsackie B virus and it’s mode of transmission?

A
  • Summer and fall
  • Fecal-oral transmission
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15
Q

What are 4 clinical manifestations caused by Coxsackie B virus?

A
  • URI
  • Pleurodynia (Devil’s grip - severe intercostal pain and fever)
  • Myocarditis (most common infectious etiology)
  • Aseptic meningitis
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16
Q

Which parasitic cause of Myocarditis is described as a hemoflagellate (intracellular protozoa)?

A

Trypansoma cruzi

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17
Q

What are 2 diagnostic methods for Chagas disease (Trypanosoma cruzi)?

A
  • Peripheral smear for trypomastigotes
  • Xenodiagnosis
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18
Q

Signs/sx’s of acute phase Chagas Disease?

A
  • Chagoma, Romana sign
  • Fever, malaise, LAD
  • CV: myocarditis
  • CNS: severe meningoencephalitis (young pt’s)
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19
Q

What are the sign/sx’s of chronic Chagas Disease, both CV and GI?

A
  • CV: dilated cardiomyopathy, arrhythmias
  • Megalcolon and achalasia
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20
Q

What type of helminth is Trichinella spiralis**?

A

Invasive nematode

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21
Q

How is Trichinella spiralis transmitted?

A

Ingestions of cysts from raw pork (boars OR even horses)

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22
Q

Explain the life cyle of Trichinella spiralis upon ingestion of cysts, where do larvae mature and disseminate?

A
  • Develop in gut –> mate –> larvae disseminate hematogenously
  • Penetrate muscle tissue: skeletal, heart, and brain
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23
Q

What are the signs/sx’s Trichinella spiralis based on location in the body?

A
  • Abdominal pain, diarrhea, fever (small intestines)
  • Muscle aches (muscle invasion)
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24
Q

Periorbital edema, myositis, and eosinophilia should make you consider the diagnosis of which organism?

A

Trichinella spiralis

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25
Q

What are diagnostic techniques utilized for Trichinella Spiralis?

A
  • Serologic (ELISA, etc.)
  • Latex agglutination
  • CPK levels
  • Muscle biopsy
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26
Q

Extension of myocarditis into the pericardium is termed what?

A

Myopericarditis

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27
Q

What are the common presenting signs/sx’s of Pericarditis?

A
  • Chest pain that is sharp, often positional and pleuritic in nature
  • Often relieved by leaning forwards
  • Fever
  • Palpitations
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28
Q

What are the common PE findings associated with Pericarditis?

A
  • Friction rub upon auscultation
  • Rapid or irregular pulse
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29
Q

What is the hallmark EKG findings and in what leads for Pericarditis?

A

DIFFUSE ST elevations w/ RECIPROCAL dpressions in leads aVR and V1 w/ PR depression

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30
Q

Majority of CXRs with pericarditis show minimal abnormalities, what is the exception?

What characteristic findings?

A
  • Pericardial effusion >250 mL –> symmetrically enlarged cardiac silhoutte
  • “Water bottle sign”
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31
Q

Which imaging modality should be used in pericarditis to assess for pericardial effusion and/or tamponade, as it is more sensitive than CXR.

A

Transthoracic Echocardiogram

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32
Q

What would be a PE finding in pt with suspected Pericarditis that would warrant blood cultures?

A

Temp >38°C

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33
Q

What labs would be useful for diagnosing Pericarditis?

A
  • Cardiac enzymes (serial)
  • CBC w/ diff
  • ESR
  • CRP
  • Blood cultures if temp >38°C
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34
Q

What is a possible complication of Pericarditis and how is it treated?

A
  • Cardiac Tamponade
  • Tx w/ pericardiocentesis

*Counsel about activity restrictions*

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35
Q

Which drugs should be utilized in Pericarditis due to viral etiology?

What is contraindicated?

A
  • High dose ASPIRIN x3/day (ibuprofen, Indomethacin are options too)

AND

  • Colchicine
  • ANTICOAGULANTS ARE CONTRAINDICATED!!!!
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36
Q

Which infectious agent most often causes serous pericarditis and which most often causes causeous pericarditis?

A
  • Coxsackie B = serous pericarditis
  • Mycobacterium tuberculosis = caseous pericarditis
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37
Q

What is distinct morphology of Mycobacterium Tuberculosis?

Oxygen dependency and facultative intracellular in what?

A
  • Acid fast bacillus (weakly G +)
  • Obligate aerobes
  • Facultative intracellular in Macrophages
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38
Q

Due to the mycolic acid cell wall composition Mycobacterium tuberculosis is highly resistant to what?

A

Desiccation (drying out) including NaOH

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39
Q

The virulence of Mycobacterium Tuberculosis is related to what factors?

A
  • Facultative intracellular
  • Sulafatides
  • Cord factor
  • Surface protein can cause delayed hypersensitivity and cell mediated immune rxn
  • Wax D
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40
Q

Which 2 stains can be used for Mycobacterium Tuberculosis and the appearance of the organism with each?

A
  • Acid Fast (Ziehl-Neelsen, Kinyon) = “red rods“
  • Auramin-rhodamine stain = fluorescent apple green color
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41
Q

Although, the main manifestation of mycobacteirum tuberculosis is pulmonary TB, how can it cause caseating pericarditis?

A

Direct lymphatic or hematogenous diseemination

42
Q

Infective endocarditis (IE) starts with what?

A

Bacteremia

43
Q

What are the constitutional sx’s associated with Infective Endocarditis (IE)?

A
  • Fever, chills
  • Weight loss
  • New/worsening murmur
  • Fatigue
  • Arthralgia and myalgia
44
Q

How do the signs and sx’s of Acute IE differ from Subacute IE?

A
  • Acute = RAPID progrssion of sx’s and cardiac damage –> high fever, chills, weakness SOB, pleuritic chest pain
  • Subacute = INDOLENT course w/ low grade fever, weight loss over time, fatigue, arthralgia/myalgia
45
Q

What are 5 possible complications of Infective Endocarditis (IE)?

A
  • Congestive heart failure
  • Abscess formation
  • Hematogenous spread
  • Embolism
  • Systemic immune rxn –> death
46
Q

Which side of the heart and valves are most often affected in acute vs. subacute IE?

A
  • Acute IE: R side > L side –> Tricuspid > aortic, especially w/ S. aureus
  • Subacute IE: L side > R side –> Mitral or aortic valve
47
Q

What are the diagnostic studies (imaging)/labs indicated for Infective Endocarditis?

Why is a UA indicated?

A
  • Blood culture x3 (ALWAYS prior to Abx)
  • CBC w/ diff + CMP + ESR and CRP
  • EKG and CXR and Transesophageal echocardiogram (US)
  • UA (assess for hematuria)
48
Q

Using the DUKE criteria for diagnosis of IE, what are the 4 major criteria?

A
  • Blood culture positive for IE
  • Evidence of endocardial involvement
  • Echocardiogram positive for IE
  • New valvular regurgitation (worsening or changing or preexisting murmur NOT sufficient)
49
Q

Using the DUKE criteria for diagnosis of IE, microorganisms consistent with IE from persistently (+) blood cultures is defined as what?

A
  • At least 2 positive blood cultures of blood samples draw >12 hr apart

OR

  • All of three or a majority of ≥4 seprate cultures of blood (w/ first and last sample drawn at least 1 hr apart)
50
Q

Transesophageal echocardiogram (TEE) is recommended in pt’s under what 3 conditions?

A
  • Pt’s with prosthetic valves
  • Rated at least “possible IE” by clinical criteria
  • Complicated IE (paravalvular abscess)
51
Q

What are the 6 minor criteria as defined by the DUKE criterias for diagnosis of IE?

A
  • Predisposition, predisposing heart condition of IV drug use
  • Fever, temp >38°C
  • Vascular phenomena
  • Immunologic phenomena
  • Microbiological evidence
  • Echocardiographic minor criteria eliminated
52
Q

Which microbiological evidence is considered minor using the DUKE criteria for IE?

A
  • Positive blood culture but does NOT meet a major criterion
  • Serological evidence of acute infection w/ organisms inconsistent w/ IE
53
Q

Using the DUKE criteria for diagnosis of IE how many major, minor, or combination needs to be met for definitive diagnosis?

A
  • 2 major criteria

OR

  • 1 major and 3 minor criteria

OR

  • 5 minor criteria
54
Q

What are the risk factors/considered high risk pt’s for Infective Endocarditis (including age, sex, and underlying conditions)?

A
  • Age >60 and M>F
  • Poor dentition
  • IV drug abuse
  • Structural, congenital or valvular HD
  • Prosthetic valve replacement
  • Rheumatic heart disease
55
Q

If pt with IE goes into cardiogenic shock, what is the treatment?

A

Surgery ASAP

56
Q

After obtaining blood cultures in pt with acute/toxic IE, you should start emperic Abx utilizing what 2 Abx?

A

Vancomycin +/- Gentamicin

57
Q

It may not be necessary to initiate empiric Abx for which type of IE and can be best to wait for culture and sensitivites to target a specific organim?

58
Q

Pt’s considered high risk for IE can be given prophylactic Abx prior to dental or respiratory procedures, what is given if they are able to take PO medication?

A

Amoxicillin

59
Q

Pt’s considered high risk for IE can be given prophylactic Abx prior to dental or respiratory procedures, what are 3 options if they are unable to take PO and need IV?

A

Ampicillin or Cefazolin or Ceftriaxone

60
Q

Pt’s considered high risk for IE can be given prophylactic Abx prior to dental or respiratory procedures, what are 4 options if they are allergic to penicillin (PCN)?

A

Desensitize v. Cephalexin v. Clindamycin v. Azithromycin

61
Q

What are the 4 most common infectious agents causing IE?

A
  • S. aureus
  • S. epidermidis
  • S. viridans
  • Enterococcus (Group D strep)
62
Q

What are the 4 rare etiologic agents that can cause of IE?

A
  • HACEK group
  • Coxiella burnetti
  • Brucella sp.
  • S. agalactiae
63
Q

A single positive blood culture for which agent is considered as meeting a major criteria when using DUKE for the dx of IE?

A

Coxiella burnetti

64
Q

What is the morphology and major characteristics of S. aureus?

A
  • Gram (+) cocci, clusters
  • Coagulase AND catalase (+)
  • Facultative anaerobe
65
Q

S. aureusis a normal component of which flora and colonizes where in humans?

A
  • Normal flora on skin (can breach)
  • Colonizes the nasopharynx
66
Q

A gram stain taken from a pt with Infective Endocarditis is shown, what organism is this most consistent with?

A

S. aureus = Gram (+) cocci in clusters

67
Q

Which 5 virulence factors of S. aureus allow for host cell evasion?

Function of each.

A
  • Protein A: prevents opsonization by binding Fc of IgG
  • Coagulase: forms fibrin clot around organism
  • Catalase: breaks down H2O2
  • Hemolysins: destroy RBC
  • Leukocydins: destroy WBC
68
Q

Which 3 virulence factors allow for invasion of tissue and bloodstream by S. aureus?

A
  • Hyaluronidase: breaks down CT
  • Staphylokinase: lyses formed clots
  • Lipase: breaks down fat
69
Q

What are the 3 toxin mediated manifestations caused by S. aureus?

A
  • Food poisoning
  • Scalded Skin Syndrome (SSS)
  • Toxic Shock Syndrome
70
Q

What are local manifestations of the skin and respiratory tract caused by S. aureus?

A
  • Skin: impetigo, cellulitis, folliculitis, furuncles, carbuncles
  • Respiratory: pneumonia (cavitary)
71
Q

What are the 4 systemic manifestations caused by S. aureus?

A
  • Acute endocarditis (Tricuspid valve)
  • Meningitis
  • Osteomyelitis (#1 cause in adults AND children)
  • Septic arthritis
72
Q

What are the signs/sx’s of acute endocarditis caused by S. aureus?

A
  • Fever and chills and night sweats
  • Fatigue, dyspnea
  • CHF
73
Q

For systemic disease caused by S. aureus what is an exception choice of Abx?

For MSSA?

A
  • Vancomycin is exceptional choice
  • For MSSA use Nafcillin
74
Q

What is the morphology of Streptococcus viridans and major characteristics (O2 dependence, catalase, optochin..)?

A
  • Gram (+) cocci in CHAINS
  • α-hemolytic (green zone) + catalase negative + Optochin resistant
  • Facultative anaerobe
75
Q

S. viridans is a normal inhabitant of where?

A

Normal oral flora, nasopharynx, and GI tract

76
Q

Which virulence factor of S. viridans allows for binding to heart valves?

A

Extracellular dextran

77
Q

What are 2 clinical manifestations caused by S. viridans?

A
  • Dental caries
  • Subacute endocarditis
78
Q

Which Abx is used for S. viridans?

A

Penicillin (PCN)

79
Q

Which cause of infectious endocarditis is novobicin sensitive?

A

Staphylococcus epidermidis

*Sketchy = naval exposed and plumber is sensitive

80
Q

What are morphological and major characteristics of Staphylococcus epidermidis (O2 dependence, coagulase/catalase)?

A
  • Gram (+) cocci in clusters
  • Coagulase negative AND catalase positive
  • Novobicin sensitive
  • Facultative anaerobe
81
Q

Staphylococcus epidermidis is a normal inhabitant of?

A

Normal flora of skin

82
Q

What are the 2 virulence factors of S. epidermidis and which allows it specifically to adhere to prosthetic devices/indwelling catheters?

A
  • Adhesion polysaccharide capsule –> prosthetic’s/catheters
  • Biofilm formation

*Gunk under sink, tubing under sink (cathether), plumber working on pipes (prosthetics)

83
Q

Which staphylococcus is coagulase negative staph (CoNS)?

A

S. epidermidis

84
Q

Staphylococcus epidermidis is extremely Abx resistant, so treat with which Abx?

A

Vancomycin

85
Q

Vegetations of a prosthetic device, including knees and valves of the heart should make you think of what organism?

A

S. epidermidis

86
Q

What are 2 systemic manifestations of S. epidermidis?

A
  • SUBacute endocarditis
  • Infection and bacteremia in neutropenic pt’s (susceptible)
87
Q

What are the morphological and major characteristics of Enterococcus faecalis (Group D strep)?

i.e., O2 dependence, catalase, and hemolytic nature

A
  • Gram (+) cocci
  • Catalase negative
  • Facultative anaerobe
  • Variable hemolytic nature (alpha or gamma)
88
Q

What is the virulence factor of Enterococcus faecalis (Group D strep), allows it to bind what?

A

Extracellular dextran helps bind heart valves

89
Q

What are 3 clinical manifestations caused by both Enterococcus faecalis or Streptococcus bovis (Group D strep)?

A
  • SUBacute endocarditis
  • UTI’s
  • Biliary tract infections
90
Q

Forms of Enterococcus faecalis resistant to what Abx are on the rise?

A

Vancomycin

91
Q

Which non-enterococci (group D strep) is associated with colon cancer and IBD?

A

Streptococcus bovis

92
Q

What are the morphological and major characteristics of Streptococcus bovis?

i.e., O2 dependence, catalase, hemolysis..

A
  • Gram (+) cocci in chains
  • Catalase negative
  • Facultative anaerobe
  • Variable hemolytic nature (α or γ)
93
Q

Which media can you grow the group D strep, E. faecalis and S. bovis on?

What is one major difference.

A
  • E. faecalis = 40% bile AND 6.5% NaCl or blood agar
    • S. bovis* = 40% bile and Blood agar
94
Q

What are the morphological characteristics of the HACEK group of organisms?

A

Gram (-) group of bacilli + fastidious

95
Q

Which agar can be used for the HACEK group of organisms?

A

Chocolate agar

96
Q

The HACEK group of organism are a part of which normal flora?

A

Oral flora

97
Q

Which type of Haemophilus sp is most likely to cause endocarditis?

A

H. parainfluenzae

98
Q

Haemophilus sp. typically cannot grow up blood agar unless placed on same place as S. aureus, will show what type of growth?

Why?

A
  • Stellate growth
  • Due to virulence factor of S. aureus, hemolysins, which will lyse the RBC’s
99
Q

What is the morphology and major characteristics of Coxiella burnetti?

A
  • Gram (-) and pleomorphic
  • Aerobic + zoonotic
  • Obligate intracellular
100
Q

What is the mode of transmission for Coxiella burnetti?

A

Aerosol transmission

CVM Exam 2 (15 decks)

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