<s>[INST] context: Various drugs can cause drug-induced interstitial nephritis, including sulfonamides, penicillin, cephalosporins, the fluoroquinolone antibiotics ciprofloxacin and norfloxacin, and the antituberculous drugs isoniazid and rifampin. Acute tubulointerstitial nephritis also can occur with the use of thiazide and loop diuretics, cimetidine, ranitidine, omeprazole, and nonsteroidal anti-inflammatory drugs. The disease manifests about 2 weeks after the patient begins to use the drug. Elements of type I (increased IgE) and type IV (skin test positivity to drug haptens) hypersensitivity are present. Congestive heart failure can lead to acute tubular injury, but it is not associated with a rash or proteinuria. The hemolytic uremic syndrome can occur after ingestion of strains of Escherichia coli that may be present in ground beef. Poststreptococcal glomerulonephritis (GN) could account for the proteinuria and hematuria seen in this patient, but not for the rash because the strains of group A p-hemolytic streptococci that cause a skin infection precede by weeks the development of GN. WBCs, but not eosinophils, may be present in the urine of a patient with a urinary tract infection. [/INST] question: A 32-year-old man developed a fever and rash over 3 days. Five days later, he has increasing malaise. On physical examination, the maculopapular erythematous rash on his trunk has nearly faded away. His temperature is 37.1degC, and his blood pressure is 135/85 mm Hg. Laboratory studies show a serum creatinine level of 2.8 mg/dL and blood urea nitrogen level of 29 mg/dL. Urinalysis shows 2+ proteinuria; 1+ hematuria; and no glucose, ketones, or nitrite. The leukocyte esterase result is positive. Microscopic examination of urine shows RBCs and WBCs, some of which are eosinophils. Which of the following most likely precipitated his renal disease? | options: A: Antibiotic ingestion B: Congestive heart failure C: Eating poorly cooked ground beef D: Streptococcal pharyngitis | answer: A </s>