Which statement best describes the etiologic agent of Q fever?

Which statement best describes the etiologic agent of Q fever?

• A. Coxiella burnetii
• B. Salmonella pullorum
• C. Escherichia coli
• D. Pasteurella multocida

Answer: (A)

Q fever is caused by Coxiella burnetii, a small Gram-negative bacterium that is an intracellular pathogen. It primarily infects livestock such as cattle, sheep, and goats, and humans usually contract it by inhaling contaminated aerosols from birth products, urine, milk, or dust. A notable feature is its environmental resilience and ability to exist in a spore-like form, with antigenic variation between phase I and phase II LPS that influences testing and disease course. Because it is an obligate intracellular organism and requires specialized biosafety conditions to culture, it is not something seen in routine labs. The other organisms listed are associated with different diseases or hosts, not Q fever, making Coxiella burnetii the correct etiologic agent.

Q fever is caused by Coxiella burnetii, a small Gram-negative bacterium that is an intracellular pathogen. It primarily infects livestock such as cattle, sheep, and goats, and humans usually contract it by inhaling contaminated aerosols from birth products, urine, milk, or dust. A notable feature is its environmental resilience and ability to exist in a spore-like form, with antigenic variation between phase I and phase II LPS that influences testing and disease course. Because it is an obligate intracellular organism and requires specialized biosafety conditions to culture, it is not something seen in routine labs. The other organisms listed are associated with different diseases or hosts, not Q fever, making Coxiella burnetii the correct etiologic agent.