From the Research
Coxiella burnetii is typically cultured using cell culture systems, such as embryonated chicken eggs and cell lines like Vero cells, L929 mouse fibroblasts, or human monocytic cell lines, which provide the necessary acidic environment for its growth and replication 1.
Culture Requirements
The culture of Coxiella burnetii requires specialized techniques due to its highly infectious nature and obligate intracellular lifestyle.
- Cell culture systems are the primary method for cultivating this bacterium
- Biosafety Level 3 (BSL-3) containment facilities are mandatory for Coxiella cultivation due to its high infectivity and potential for aerosol transmission
- The bacterium exhibits a unique biphasic developmental cycle, transitioning between small cell variants (SCVs) and large cell variants (LCVs) within acidified phagolysosomes of host cells
Growth Conditions
- The acidic environment (pH 4.5-5.0) is essential for its metabolism and replication
- Growth is slow, typically requiring 2-6 weeks for visible infection
- Modern axenic (cell-free) media systems have been developed that mimic the acidic phagolysosomal environment, allowing cultivation without host cells, though these are primarily used in research settings rather than diagnostic laboratories
Diagnostic Preferences
- Due to culture difficulties and biosafety concerns, molecular methods like PCR are often preferred for diagnosis in clinical settings 2, 3
- The diagnosis of Q fever is mainly serological, and treatment is effective and well tolerated, but must be adapted to the acute or chronic pattern, the presence of a heart valve disease, an aneurysm or a vascular prosthesis, an immunodeficiency, and the specific problem of pregnancy 4, 5