**Question:** Drug of choice in pneumonia is:

A. Amoxicillin
B. Azithromycin
C. Ceftriaxone
D. Metronidazole

**Core Concept:**
Pneumonia is a respiratory infection that can be caused by various pathogens, including bacteria, viruses, and fungi. Treatment selection depends on the identified causative agent and the patient's clinical condition. Antibiotics are the primary treatment for bacterial pneumonia.

**Why the Correct Answer is Right:**
Ceftriaxone (option C) is a broad-spectrum third-generation cephalosporin, which has activity against a wide range of Gram-positive and Gram-negative bacteria, including Streptococcus pneumoniae and Haemophilus influenzae. It is often used for treating pneumonia due to its efficacy and once-daily dosing, which makes it a convenient choice for managing this condition.

**Why Each Wrong Option is Incorrect:**

A. Amoxicillin (option A) is a penicillin antibiotic that primarily targets Gram-negative bacteria. Though effective against some Gram-positive organisms, it is less effective against S. pneumoniae and H. influenzae compared to ceftriaxone.

B. Azithromycin (option B) is a macrolide antibiotic, which is effective against some Gram-positive and Gram-negative bacteria, but it has limited activity against S. pneumoniae.

D. Metronidazole (option D) is an antiprotozoal drug used for treating infections caused by anaerobic bacteria and protozoa. It is not a suitable choice for treating bacterial pneumonia due to its narrow spectrum of activity and the preference for ceftriaxone or other broad-spectrum antibiotics.

**Clinical Pearl:**
In cases of suspected pneumonia, it is essential to identify the causative agent to ensure appropriate treatment. Ceftriaxone is a broad-spectrum antibiotic suitable for treating bacterial pneumonia, especially when considering the patient's condition and the need for once-daily dosing.

**Correct Answer:**
Ceftriaxone (option C) is the correct choice among the given options for the treatment of pneumonia due to its broad spectrum of action, once-daily dosing, and the ability to cover common causative organisms like S. pneumoniae and H. influenzae.