0%
Topic
Review Topic
0
0
Topic
Snapshot
  • A 50-year-old man presents to the emergency room for prolonged fever, shortness of breath, and chest pain. He is admitted for heart failure and suspected endocarditis. A cardiac echocardiogram shows vegetation on the valves. The initial blood cultures are negative. Upon further investigation, he works at a leather supplier and often visits farms to evaluate the cattle. He is treated for a suspected zoonotic endocarditis with doxycycline and hydrochloroquine.
Introduction
  • Classification
    • Coxiella burnetii
      • obligate intracellular gram-negative bacteria
      • Legionellales order
      • causes Q fever and culture-negative bacterial endocarditis
      • transmitted from farm animals (sheep, goat, and cattle amniotic fluid) via inhalation of aerosolized spores even at low doses
      • no arthropod vector
  • Epidemiology
    • incidence
      • found worldwide
    • risk factors
      • exposure to farm animals
      • occupational exposure to animal products (e.g., animal hides)
      • immunosuppression
  • Pathogenesis
    • C. burnetii is able to replicate in phagocytic vacuoles in low pH environments
    • can survive oxidative and osmotic stress
    • can survive in the environment for years
  • Prevention
    • Q fever vaccine is available in Australia for those with high occupational risk
  • Prognosis
    • may have prolonged course if untreated
    • most cases resolve with treatment
Presentation
  • Symptoms
    • fever and headaches
    • chronic infection
      • weight loss
      • night sweats
    • acute infection
      • pneumonia
        • cough
        • sore throat
  • Physical exam
    • acute infection
      • pneumonia
        • rhonchi on lung exam
        • shortness of breath
    • chronic infection
      • endocarditis
        • heart failure
        • shortness of breath
      • vascular infection
        • abdominal pain
        • infected aneurysm
        • vascular rupture
      • osteomyelitis
        • tenosynovitis
        • tenderness at the site of infection
      • hepatitis
        • jaundice
Imaging
  • Chest radiography
    • indication
      • suspected pneumonia from acute Q fever
    • findings
      • lobar opacities or patchy infiltrates
  • Echocardiography
    • indication
      • suspected endocarditis from chronic Q fever
    • findings
      • vegetation on valves, most commonly mitral valve
Studies
  • Labs
    • blood cultures are usually negative
    • transaminitis
    • elevated erythrocyte sedimentation rate or C-reactive protein
    • confirmatory testing
      • detection of immunoglobulin G (IgG) on serology
      • detection of DNA on polymerase chain reaction
  • Making the diagnosis
    • based on clinical presentation and laboratory studies
    • suspect Q fever in cases of culture-negative endocarditis
Differential
  • Tularemia
    • distinguishing factor
      • typically presents with a maculopapular rash that may ulcerate
  • Bacterial endocarditis
    • distinguishing factors
      • blood cultures are usually positive
      • other culture-negative endocarditis to consider are
        • Bartonella spp
        • HACEK (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, and Kingella)
Treatment
  • Medical
    • doxycycline
      • indication
        • all patients
    • hydroxychloroquine
      • indication
        • chronic Q fever
        • given with doxycycline
    • trimethoprim/sulfamethoxazole
      • indication
        • for pregnant women
      • outcome
        • may reduce fetal death
Complications
  • Adverse fetal outcomes in pregnant women

Please rate topic.

Average 5.0 of 1 Ratings

EXPERT COMMENTS (0)
Private Note