Infections of the CVS II Flashcards
describe the HACEK group
G-ve rods, slowly growing in chocolate agar
- Haemophilus species
- Aggregatibacter sp.
- Cardiobacterium
- Eikenella
- Kingella
describe the epidemiology and clinical presentation of HACEK
- 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
Aggregatibacter sp. and Cardiobacterium sp. are part of the ____ family
describe lab diagnosis
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
describe microbial characteristics of Aggregatibacter sp.
- 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
describe the microbial pathogenesis of A. actinomycetemcomitans
- 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
- direct contact transmission:
describe characteristics of Cardiobacterium sp .
- species: C. vulvarum, C. hominis
- G-ve or gram-variable rods
- catalase negative and oxidase positive
describe the risks and epidemiology of Cardiobacterium sp.
- risks: history of dental treatment or oral disease exclusively
- epidemiology: normal flora of oropharynx in 2/3 of healthy individuals
summarize the differences between Aggregatibacter and Cardiobacterium
describe the G-ve rods that can cause endocarditis
- G-ve rods
- HACEK group
- E. coli, Klebsiella
- Pseudomonas aeruginosa
- IVDU rare
- Neisseria gonorrhea
describe Pseudomonas aeruginosa
- 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
___ looks green on Mueller-Hinton
Pseudomonas aeruginosa looks green on Mueller-Hinton
Pseudomonas aeruginosa is ____ & _____-positive but ____-negative
Pseudomonas aeruginosa is glucose & citrate-positive but indole-negative
describe intracellular bacteria involved in IE
- 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
- Bartonella sp.: subacute, lice bite, animal contact
____ are the most common viruses involved in pericarditis
Coxsackie virus and echovirus are the most common viruses involved in pericarditis
HIV and CMV can cause pericarditis as well
____ are the most common bacteria involved in pericarditis
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
describe myocarditis and its etiology
myocarditis is inflammation of the heart muscle
- etiology:
- USA: viral dominates
- worldwide: parasitic
describe the symptoms or myocarditis in adults
- 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
describe the presentation of myocarditis in young children
- less specific malaise, loss of appetite, abdominal pain and chronic cough
- later difficulty breathing, mistaken for asthma
describe symptoms of myocarditis if viral etiology
- if viral: fever, rash, diarrhea, joint pains, fatigue
describe the pathogenesis of myocarditis
- 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
describe diagnosis of myocarditis
- 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
describe the lab diagnosis of myocarditis
-
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
describe causative viruses of myocarditis
- 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
list causative bacteria in myocarditis
- G+: Staphylococcus, Streptococcus, Mycobacterium
- G-: Chlamydophila psittaci, Borrelia burdorferi, Brucella, Tropheryma whipplei, Leptospirosis, Rickettsia, Treponema pallidum, Salmonella typhi, V. cholerae
list the fungal causative agents of myocarditis
- fungal: Aspergillus sp., Blastomyces, Candida, Coccidiodes, Cryptococcus, Histoplasma, Sporothrix
list the parasitic causative agents of myocarditis
- Paragonimus westermani, Baylisascarisprocyonis, Toxocara
list the protozoal causative agents of myocarditis
- Trypanosoma cruzii, Toxoplasma gondii, Leishmania, Enteroamoeba
describe Paragonimus westermani
- 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
describe the life cycle of P. westermani/lung fluke
describe the lab diagnosis of Toxocara sp. and Bayliascaris sp.
describe the pathogenesis of Toxocara sp. and Bayliascaris sp.
describe the transmission of Toxocara sp.
describe the clinical presentation of Toxocara sp. and Baylisascaris
