Which organism is the causative agent of tularemia?

Which organism is the causative agent of tularemia?

• A. Francisella tularensis
• B. Mycobacterium tuberculosis
• C. Yersinia pestis
• D. Brucella melitensis

Answer: (D)

Tularemia is caused by Francisella tularensis, a small Gram-negative coccobacillus that often persists intracellularly within macrophages. It is a zoonotic infection carried by animals such as rabbits and rodents, and humans can acquire it through flea or tick bites, direct handling of infected animals, or inhalation/ingestion of contaminated material. The disease can present in multiple forms—ulceroglandular, pneumonic, and others—depending on the route of entry, reflecting how the organism interacts with the host. The other bacteria listed cause different diseases: Mycobacterium tuberculosis causes tuberculosis, Yersinia pestis causes plague, and Brucella melitensis causes brucellosis.

Tularemia is caused by Francisella tularensis, a small Gram-negative coccobacillus that often persists intracellularly within macrophages. It is a zoonotic infection carried by animals such as rabbits and rodents, and humans can acquire it through flea or tick bites, direct handling of infected animals, or inhalation/ingestion of contaminated material. The disease can present in multiple forms—ulceroglandular, pneumonic, and others—depending on the route of entry, reflecting how the organism interacts with the host.

The other bacteria listed cause different diseases: Mycobacterium tuberculosis causes tuberculosis, Yersinia pestis causes plague, and Brucella melitensis causes brucellosis.