<prompt> After treatment of pneumonia, a child developed pseudomembranous colitis. Which of the following drug frequently causes pseudomembranous colitis?ClindamycinGararnycinErythromycinVancomycin  <response>: Alteration of the normal enterocolonic bacterial flora by prior antibiotic administration is required for the development of C difficile colitis in the large majority of those who develop the disease. Antibiotics most often associated with C difficile-induced disease include aminopenicillins, fluoroquinolones, cephalosporins, and clindamycin. Also cancer chemotherapy or preexisting IBD, especially with colonic involvement, appears to trigger C difficile colitis. Oral metronidazole or vancomycin should be given and fluids replaced. Ref: Trier J.S. 2012. Chapter 5. Acute Diarrheal Disorders. In N.J. Greenberger, R.S. Blumberg, R. Burakoff Eds, CURRENT Diagnosis Treatment: Gastroenterology, Hepatology, Endoscopy, 2e. 