An 8-year-old boy presents with headaches, dizziness, and malaise approximately 2 weeks after a severe sore throat. His mother describes puffiness of his face and darkening of his urine. She also notes that her son is passing less urine and that he is becoming increasingly short of breath. On physical examination, there is anasarca, hypertension (190/130 mm Hg), and tachycardia. The urine is scanty and brownish red. Urinalysis shows 3+ proteinuria. Microscopic examination of the urine discloses numerous RBCs, as well as occasional granular and red cell casts. A renal biopsy is stained by direct immunofluorescence microscopy for complement C3, and the results are shown. Which of the following is the most likely cause of acute postinfectious glomerulonephritis in the patient?
Acute postinfectious glomerulonephritis is an immune complex disease of childhood, which occurs after an infection with group A (b -hemolytic) streptococci and is caused by the deposition of immune complexes in glomeruli. Occasional examples are caused by staphylococcal infection (e.g., acute staphylococcal endocarditis, staphylococcal abscess), and rare cases result from viral (e.g., hepatitis B) or parasitic (e.g., malaria) infections. The primary infection involves the pharynx or, in hot and humid environments, the skin. In recent years, the proportion of cases of acute postinfectious glomerulonephritis caused by staphylococcal infection (choice E) has been increasing.Diagnosis: Nephritic syndrome, acute postinfectious glomerulonephritis
Escherichia coli
Epstein-Barr virus
Group A (b-hemolytic) streptococci
Klebsiella sp.
Kidney