Infections of the CVS II

Question 1

describe the HACEK group

Answer 1

G-ve rods, slowly growing in chocolate agar

• Haemophilus species
• Aggregatibacter sp.
• Cardiobacterium
• Eikenella
• Kingella

Question 2

describe the epidemiology and clinical presentation of HACEK

Answer 2

• normal flora of the oropharynx
• most common G-ve isolated from subacute NIE and early onset PVIE
• clinical signs are non-specific:
  
  • long-term course (over 1 year)
  • large friable vegetations, frequent emboli
  • weeks of history of low-grade fever (50%)
  • night sweats, fatigue
  • tricuspid systolic murmur
  • splenomegaly

Question 3

Aggregatibacter sp. and Cardiobacterium sp. are part of the ____ family

describe lab diagnosis

Answer 3

Aggregatibacter sp. and Cardiobacterium sp. are part of the Pasteurellaceae family

G-ve facultative anaerobic rods

• no hemolysis on sheep blood agar
• ask for PCR or Maldi-Tof as a follow up of blood culture

Question 4

describe microbial characteristics of Aggregatibacter sp.

Answer 4

• catalase positive and oxidase negative
• cultures result in star-like colonies and G-ve “crossed cigars” cells
• adherent colonies with rough surface and after sub-culturing become mucoid and non-adherent

Question 5

describe the microbial pathogenesis of A. actinomycetemcomitans

Answer 5

• biofilm formers and invade tissues because they:
  
  • do not induce apoptosis
  • evade immune system
    
    • leukotoxin A
    • inhibit antibody production and activate T-suppressor cells
    • resistant to complement-mediated killing
• antimicrobial resistant
  
  • direct contact transmission:
    
    • exposure to human or canine saliva
    • wound and deeper-tissue infxns
    • dental or urologic infxn
    • IV drug abuse
    • eye or sinus infxns

Question 6

describe characteristics of Cardiobacterium sp .

Answer 6

• species: C. vulvarum, C. hominis
• G-ve or gram-variable rods
• catalase negative and oxidase positive

Question 7

describe the risks and epidemiology of Cardiobacterium sp.

Answer 7

• risks: history of dental treatment or oral disease exclusively
• epidemiology: normal flora of oropharynx in 2/3 of healthy individuals

Question 8

summarize the differences between Aggregatibacter and Cardiobacterium

Answer 8

Question 9

describe the G-ve rods that can cause endocarditis

Answer 9

• G-ve rods
  
  • HACEK group
  • E. coli, Klebsiella
  • Pseudomonas aeruginosa
    
    • IVDU rare
  • Neisseria gonorrhea

Question 10

describe Pseudomonas aeruginosa

Answer 10

• rare in IE, most cases in mixed microbial IVDU IE
• aerobic G-ve rod
• motile when sessile, an active biofilm former
• catalase-positive and oxidase-positive
• looks green on culture on Muller Hinton agar
• B-hemolytic, glucose and citrate-positive but indole-negative

Question 11

___ looks green on Mueller-Hinton

Answer 11

Pseudomonas aeruginosa looks green on Mueller-Hinton

Question 12

Pseudomonas aeruginosa is ____ & _____-positive but ____-negative

Answer 12

Pseudomonas aeruginosa is glucose & citrate-positive but indole-negative

Question 13

describe intracellular bacteria involved in IE

Answer 13

• G-ve bacteria:
  
  • Bartonella sp.: subacute, lice bite, animal contact
    
    • B. quintana or B. henselae, 95% of “culture negative” IE cases
    • B. elizabethae, B. vinsonii, B. koehlerae, B. alsatica
  • Borrelia burdoferi in tick-infested areas
  • Legionella longbeachae, 6 months past aortic valve replacement, lung infxns, pot plants
  • Coxiella burnetti transmitted via lice

Question 14

____ are the most common viruses involved in pericarditis

Answer 14

Coxsackie virus and echovirus are the most common viruses involved in pericarditis

HIV and CMV can cause pericarditis as well

Question 15

____ are the most common bacteria involved in pericarditis

Answer 15

S. aureus and S. pneumoniae are the most common bacteria involved in pericarditis

Mycobacterium tuberculosis is one of the most common infectious cause of pericarditis worldwide

Question 16

describe myocarditis and its etiology

Answer 16

myocarditis is inflammation of the heart muscle

• etiology:
  
  • USA: viral dominates
  • worldwide: parasitic

Question 17

describe the symptoms or myocarditis in adults

Answer 17

• acute, subacute (2 weeks) or chronic (more than 6 weeks)
• stabbing chest pain focal and often an acute heart failure
• diffuse pain, swellings, SOB
• CHF
• arrhythmia, fever, sweats, chills

Question 18

describe the presentation of myocarditis in young children

Answer 18

• less specific malaise, loss of appetite, abdominal pain and chronic cough
  
  • later difficulty breathing, mistaken for asthma

Question 19

describe symptoms of myocarditis if viral etiology

Answer 19

• if viral: fever, rash, diarrhea, joint pains, fatigue

Question 20

describe the pathogenesis of myocarditis

Answer 20

• acute injury leads to cardiac damage → exposure of intracellular antigens such as cardiac myosin → activation of the innate immune system
• over weeks, specific immunity that is mediated by T lymphocytes and antibodies directed against pathogens and similar endogenous heart epitopes cause robust inflammation

Question 21

describe diagnosis of myocarditis

Answer 21

• heart MRI or EKG (ST changes)
• heart failure, cardiac dysfunction on EKG and elevated cardiac enzymes (increased troponin)
• cardiac muscle biopsy for signs of inflammation and necrosis
• ultrasound to rule out heart valve problems

Question 22

describe the lab diagnosis of myocarditis

Answer 22

• complete blood count with differential
  
  • lymphocytosis or neutropenia supports diagnosis of a viral infxn
  • serum troponin, ESR, CRP
• blood culture of bacteria
• viral serology
  
  • a 4-fold increase in a specific titer from the acute to convalescent phase is strong evidence of infxn
• molecular tests:
  
  • in situ hybridization
  • PCR

Question 23

describe causative viruses of myocarditis

Answer 23

• viral infxns, most common in Europe and NA
  
  • adenovirus, coxsackie virus B, parvovirus B19, enterovirus, influenza A (H1N1), HIV, polio virus, rubella virus, HHV2, HHV6, CMV and hepatitis C

Question 24

list causative bacteria in myocarditis

Answer 24

• G+: Staphylococcus, Streptococcus, Mycobacterium
• G-: Chlamydophila psittaci, Borrelia burdorferi, Brucella, Tropheryma whipplei, Leptospirosis, Rickettsia, Treponema pallidum, Salmonella typhi, V. cholerae

Question 25

list the fungal causative agents of myocarditis

Answer 25

• fungal: Aspergillus sp., Blastomyces, Candida, Coccidiodes, Cryptococcus, Histoplasma, Sporothrix

Question 26

list the parasitic causative agents of myocarditis

Answer 26

• Paragonimus westermani, Baylisascarisprocyonis, Toxocara

Question 27

list the protozoal causative agents of myocarditis

Answer 27

• Trypanosoma cruzii, Toxoplasma gondii, Leishmania, Enteroamoeba

Question 28

describe Paragonimus westermani

Answer 28

• infectious myocarditis as a complication of lung infected with the parasitic trematode
• clinical and lab diagnosis:
  
  • x-ray
  • biopsy: leaf-shaped hermaphrodites
  • sputum: Giemsa or eosin stain
  • antigen or antibody detection in the serum
• epidemiology:
  
  • from freshwater crustaceans, snails and clam
  • prevalent in Asia, Japan, Korea and Latin America
  • infectious at Metacercaria stage

Question 29

describe the life cycle of P. westermani/lung fluke

Answer 29

Question 30

describe the lab diagnosis of Toxocara sp. and Bayliascaris sp.

Answer 30

Question 31

describe the pathogenesis of Toxocara sp. and Bayliascaris sp.

Answer 31

Question 32

describe the transmission of Toxocara sp.

Answer 32

Question 33

describe the clinical presentation of Toxocara sp. and Baylisascaris

Answer 33