Answer :USMLE step 2 Mcq 341:An 8yr old child developed a throat infection which resolved without any treatment


Correct Answer: E

Treatment of established infection does not prevent the development of post-streptococcal glomerulonephritis, but may lessen its severity.  Early antimicrobial therapy in affected individuals and family members may prevent the spread of streptococcal infections.  Acute post-streptococcal glomerulonephritis though not very common nowadays is seen following a throat or skin infection by nephrogenic strains of group-A beta hemolytic streptococci.  This is an immunologically mediated disease. The latent period between the infection and onset of nephritis is compatible with the time required for building up of antibodies against the streptococcal products. Granular immune deposits are seen in the glomeruli on electron microscopy due to the deposition of the circulating immune complexes. These immune complexes cause a cellular reaction consisting of neutrophils and monocytes in the glomerular basement membrane. This ultimately leads to injury and dysfunction of the basement membrane.The injury to the basement membrane is responsible for the decreased urine output due to a decreased glomerular filtration rate and also hematuria manifested by the brown colored urine. Mild proteinuria ( <1gm/day) also occurs which is responsible for the periorbital edema


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