MCQ of the Day: 29 October 2026

Answer: B. Blood culture. Step-ladder fever, relative bradycardia, coated tongue and splenomegaly in the first week suggest enteric fever caused by Salmonella enterica serovar Typhi or Paratyphi. Bacteraemia is greatest in the first week, so blood culture is the investigation of choice, with a positive rate of roughly 70 to 90% if taken before antibiotics; a large blood volume improves yield. Bone marrow culture is even more sensitive and stays positive after antibiotics, but it is invasive and is not offered here.
A. Widal agglutinins usually rise only from the second week, and a single titre is hard to read in endemic areas because of past infection, vaccination and cross-reacting antibodies.
C. Stool culture becomes positive mostly from the second or third week and is also positive in chronic carriers, so it does not confirm acute disease.
D. Urine culture is positive in a minority of patients, mainly later in the illness, and has the lowest yield of these options.