Combination antimicrobial therapyDownloads

A 72-year-old woman presents to the clinic complaining of diarrhea for the past week. She mentions intense fatigue and intermittent, cramping abdominal pain. She has not noticed any blood in her stool. She recalls an episode of pneumonia last month for which she was hospitalized and treated with antibiotics. She has traveled recently to Florida to visit her family and friends. Her past medical history is significant for hypertension, peptic ulcer disease, and hypercholesterolemia for which she takes losartan, esomeprazole, and atorvastatin. She also has osteoporosis, for which she takes calcium and vitamin D and occasional constipation for which she takes an over the counter laxative as needed. Physical examination shows lower abdominal tenderness but is otherwise insignificant. Blood pressure is 110/70 mm Hg, pulse is 80/min, and respiratory rate is 18/min. Stool testing is performed and reveals the presence of anaerobic, gram-positive bacilli. Which of the following increased this patient’s risk of developing this clinical presentation?

A 68-year-old man comes to the physician because of headache, fatigue, and nonproductive cough for 1 week. He appears pale. Pulmonary examination shows no abnormalities. Laboratory studies show a hemoglobin concentration of 9.5 g/dL and an elevated serum lactate dehydrogenase concentration. A peripheral blood smear shows normal red blood cells that are clumped together. Results of cold agglutinin titer testing show a 4-fold elevation above normal. An x-ray of the chest shows diffuse, patchy infiltrates bilaterally. Treatment is begun with an antibiotic that is also used to promote gut motility. Which of the following is the primary mechanism of action of this drug?