**Question:** Drug of choice for typhoid fever:

A. Cotrimoxazole
B. Chloramphenicol
C. Ciprofloxacin
D. Amoxicillin

**Correct Answer:** Ciprofloxacin

**Core Concept:**
Typhoid fever is a severe bacterial infection caused by Salmonella enterica serovar Typhi, commonly known as Salmonella Typhi. Symptoms include fever, headache, abdominal pain, diarrhoea, and malaise. Typhoid fever is typically treated with antibiotics, specifically, those that are effective against Salmonella Typhi.

**Why the Correct Answer is Right:**
Ciprofloxacin is a broad-spectrum fluoroquinolone antibiotic that is highly effective against Gram-negative bacteria, including Salmonella Typhi. It penetrates the blood-brain barrier, ensuring adequate coverage in the central nervous system, where Salmonella Typhi can cause meningitis. Ciprofloxacin is highly bactericidal, meaning it rapidly reduces the number of bacteria in the body, making it a suitable choice for treating typhoid fever.

**Why Each Wrong Option is Incorrect:**

A. Cotrimoxazole (trimethoprim-sulfamethoxazole): This antibiotic has limited activity against Salmonella Typhi. It is primarily effective against Gram-positive and some Gram-negative bacteria but is less effective against Salmonella Typhi.

B. Chloramphenicol: Although Chloramphenicol is effective against Salmonella Typhi, it has a significant risk of severe side effects, particularly bone marrow suppression. These side effects can lead to agranulocytosis, a life-threatening condition. Ciprofloxacin is a safer alternative due to its lower risk of severe side effects.

C. Amoxicillin: Amoxicillin is a penicillin antibiotic that is not effective against Salmonella Typhi. Salmonella Typhi is a Gram-negative bacterium, and penicillins like amoxicillin are not active against these bacteria due to their cell wall structure.

D. Cotrimoxazole (trimethoprim-sulfamethoxazole): As explained above, Cotrimoxazole is less effective against Salmonella Typhi compared to Ciprofloxacin.

**Clinical Pearl:**
Ciprofloxacin is the preferred choice for treating typhoid fever due to its bactericidal activity against Salmonella Typhi, low risk of severe side effects, and better penetration into bone marrow, which is essential for treating meningitis caused by Salmonella Typhi. In contrast, the other options are either less effective against Salmonella Typhi or have significant side effects.