[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Intracellular and atypical bacteria](https://durgical.com/en/microbiology/groups/intracellular-and-atypical-bacteria/) › Coxiella burnetii

[Microbiology](https://durgical.com/en/microbiology/) · [Intracellular and atypical bacteria](https://durgical.com/en/microbiology/groups/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

## Key points

- Coxiella has no vector: it is inhaled
- Atypical pneumonia + hepatitis in a farm worker = Q fever
- Culture-negative endocarditis
- Rickettsia-like illness without rash and with negative Weil-Felix (classic exam point)

## 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 →](https://durgical.com/en/conditions/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:

- [Doxycycline](https://durgical.com/en/pharmacology/doxycycline/)
- [Hydroxychloroquine](https://durgical.com/en/pharmacology/hydroxychloroquine/)

## Prevention

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

## Memory aid

The «Q» looks like a dust speck with a tail: barn dust that is breathed in, with no tick involved.

## 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)](https://durgical.app/estudiar/?add=/en/microbiology/coxiella-burnetii/)

## Related

- [Rickettsia rickettsii / Rickettsia typhi](https://durgical.com/en/microbiology/rickettsia-rickettsii-rickettsia-typhi/)
- [Chlamydia pneumoniae / Chlamydia psittaci](https://durgical.com/en/microbiology/chlamydia-pneumoniae-chlamydia-psittaci/)

## Related conditions

- [Q fever](https://durgical.com/en/conditions/q-fever/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

[← Back to the group: Intracellular and atypical bacteria](https://durgical.com/en/microbiology/groups/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](https://www.cdc.gov/q-fever/about/index.html) (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.

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Source: https://durgical.com/en/microbiology/coxiella-burnetii/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/coxiella-burnetii/