IgA Acute Glomerulonephritis Associated with S. Aureus



IgA Acute Glomerulonephritis Associated with S. Aureus


Robert B. Colvin, MD





Key Facts


Etiology/Pathogenesis



  • Staphylococcus aureus, coagulase positive, often MRSA


  • Increased risk with diabetes mellitus, neoplasia, old age


Clinical Issues



  • Infection, septicemia


  • Acute renal failure


  • Proteinuria, nephrotic range (20-80%)


  • Purpura


  • ˜ 25% of biopsies with acute postinfectious glomerulonephritis


Microscopic Pathology



  • Glomerular involvement varies from mild mesangial hypercellularity to marked acute inflammation with crescents


  • Red cell casts common


  • Focal interstitial nephritis


Ancillary Tests



  • IgA dominant or codominant immunoglobulin, mostly mesangial


  • EM deposits primarily mesangial and paramesangial



    • Occasional subepithelial “humps”


    • “Humps” sometimes have “cups” in contrast to poststreptococcal GN


    • Occasional subendothelial deposits


Top Differential Diagnoses



  • IgA nephropathy


  • Henoch-Schönlein purpura


  • Acute glomurelonephritis from other causes







Glomerulitis may be mild in cases of IgA positive acute glomerulitis associated with Staphylococcus aureus infection. Many mononuclear and a few polymorphonuclear leukocytes are present image.






Acute glomerulonephritis associated with Staphylococcal aureus infection typically has prominent mesangial IgA deposits, which resemble IgA nephropathy or HSP.


TERMINOLOGY


Definitions



  • Acute glomerulonephritis (GN) associated with Staphylococcus aureus infection with predominance of IgA deposition


ETIOLOGY/PATHOGENESIS


Infectious Agents



  • S. aureus, coagulase positive, often methicillin resistant (MRSA)



    • Osteomyelitis, pneumonia, septic arthritis, discitis, soft tissue abscess, empyema, sinusitis, endocarditis


    • Septicemia


    • Not usually postinfectious GN but occurs during chronic infection



      • Average duration of infection is 5 weeks


Host Factors



  • Diabetes mellitus, neoplasia, old age, alcoholism


Immune Response



  • IgA antibodies to S. aureus cell membrane antigen (GenBank BAB41819.1)


  • S. aureus enterotoxins may act as superantigens, stimulating T cells and leading to polyclonal B-cell activation


  • 1 superantigen-like protein (SSL7) binds to Fc of IgA, blocking FcR activity


CLINICAL ISSUES


Presentation



  • Persistent infection, septicemia


  • Acute renal failure


  • Hematuria


  • Proteinuria, nephrotic range (20-80%)


  • Hypertension


  • Hypocomplementemia (minority)


  • Purpura


Treatment



  • Antibiotics and renal support


  • Anecdotal reports of steroids/immunosuppression


Prognosis



  • Data limited



    • Range of outcomes from complete recovery to ESRD


    • Recovery possible if infection successfully treated


  • Underlying disease and age are important factors


Prevalence



  • ˜ 25% of renal biopsies with acute postinfectious glomerulonephritis


MICROSCOPIC PATHOLOGY


Histologic Features

Tags:
Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on IgA Acute Glomerulonephritis Associated with S. Aureus

Full access? Get Clinical Tree
Get Clinical Tree app for offline access