Question:medium
A patient presents with fever for 3 weeks. On examination he has splenomegaly. Ultrasonography reveals a hypoechoic shadow in the spleen near the hilum. Gram-negative bacilli are isolated on blood culture. Which of the following is the most likely causative organism?
A patient presents with fever for 3 weeks. On examination he has splenomegaly. Ultrasonography reveals a hypoechoic shadow in the spleen near the hilum. Gram-negative bacilli are isolated on blood culture. Which of the following is the most likely causative organism?
Show Hint
Only one of the four options is a Gram-negative bacillus, and it causes enteric fever.
Updated On: Jun 24, 2026
- Cytomegalovirus
- Toxoplasma
- Salmonella
- Lymphoma virus
Show Solution
The Correct Option is C
Solution and Explanation
Read the case as a matching problem. The lab gives you the single hardest constraint: the blood culture grew a Gram-negative bacillus. That immediately rules out three of the four options, because two of them are viruses and one is a protozoan, and none of those would ever be reported as a Gram-negative rod on a bacterial culture. Only $Salmonella$ is a Gram-negative bacillus. Now check that it also fits the story. Enteric (typhoid) fever caused by $Salmonella\ typhi$ produces a stepwise fever lasting weeks together with an enlarged spleen, and the spleen is the favourite organ for a typhoid abscess, which is exactly what the hypoechoic lesion near the hilum represents. Everything lines up, so the causative organism is Salmonella.\[\boxed{\text{Salmonella}}\]
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