DurgicalDurgical
EN
Open the app

Microbiology · Intracellular and atypical bacteria

Coxiella burnetii !

  • Bacterium
  • Gram-negative
  • For completeness

A very hardy bacterium inhaled in dust from goat, sheep and cattle births; it causes Q fever and sometimes endocarditis.

Updated 2026-11-01

Also called: Q fever

At a glance

Gram
Gram-negative
Shape
Small coccobacillus
Oxygen
Obligate intracellular (lives in an acidic vacuole)
Family
Coxiellaceae
Stain
Stains poorly with Gram; Giménez

Morphology

  • A small, very hardy form (spore-like) that survives a long time in the environment
  • Multiplies inside a phagolysosome-like vacuole

Transmission

  • Inhalation of dust contaminated with placentas, birth fluids, urine or faeces of animals
  • Raw unpasteurised milk
  • No vector needed; almost never person-to-person

Reservoir: Goats, sheep and cattle; also other animals

Isolation precautions

What the care team adds to standard precautions.

  • Standard

Virulence factors

  • Survives and grows in the acidic phagolysosome
  • Phase variation (phase I and II) of its lipopolysaccharide
  • Persists on heart valves or vascular aneurysms in chronic disease

Diseases it causes

  • Acute Q fever (fever, pneumonia, hepatitis) and chronic Q fever (endocarditis) Q fever →

Clinical picture

  • Many infections cause no symptoms
  • Acute: flu-like illness with high fever, headache, pneumonia or hepatitis
  • Chronic: culture-negative endocarditis in people with valve disease
  • No rash, unlike rickettsiae

Diagnosis

  • Serology: phase II antibodies in acute disease; high phase I in chronic disease
  • PCR on blood early in illness
  • Liver biopsy: «doughnut» granulomas (fibrin ring)

Treatment

Doxycycline for symptomatic acute Q fever. Chronic disease is treated for many months with doxycycline combined with hydroxychloroquine, which alkalinises the vacuole where the bacterium lives.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

Prevention

  • Drink pasteurised milk
  • Safe handling of placentas and birth products on farms
  • Respiratory protection in high-risk jobs

Test yourself

Think of the answer, then tap the question to see it.

What is the main route of Coxiella burnetii infection?

Inhaling dust contaminated with birth products, urine or faeces of farm animals.

Which serious complication does chronic Q fever cause?

Culture-negative endocarditis, especially in people with valve disease.

Which drug is combined with doxycycline in chronic Q fever?

Hydroxychloroquine.

Add to my cards (3)

← Back to the group: Intracellular and atypical bacteria

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: About Q fever | Q Fever | CDC (Centers for Disease Control and Prevention (CDC), 2024).

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.