A patient develops diarrhea after treatment for pneumonia. What is the treatment of choice for suspected C. difficile colitis?

The treatment of choice for suspected C. difficile colitis is metronidazole. This antibiotic is effective against Clostridium difficile, the bacterium responsible for the infection, particularly in mild to moderate cases. It works by disrupting the DNA synthesis of the bacteria, which decreases their ability to multiply and produce toxins that lead to the symptoms of colitis.

Using metronidazole as the primary treatment is aligned with clinical guidelines, which recommend it for initial episodes of C. difficile infection. In cases where the infection is more severe or in patients who have not responded to metronidazole, vancomycin may be used as an alternative treatment, but metronidazole remains the first-line choice.

The other options listed are not appropriate treatments for C. difficile colitis. Diphenoxylate/atropine is an antidiarrheal medication that is contraindicated in this condition as it can worsen the engagement of the disease. Clindamycin is known to be one of the antibiotics that can cause C. difficile infections and is not used to treat it. Ciprofloxacin is a fluoroquinolone antibiotic but does not have the activity against C. difficile that metronidazole possesses, leading it to be an ineffective