Poststreptococcal Glomerulonephritis

Post-streptococcal glomerulonephritis (PSGN) is a type of nephritis that is caused by a prior infection with group A beta-hemolytic Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus (GAS). The clinical presentation of PSGN can range from asymptomatic, microscopic hematuria to full-blown acute nephritic syndrome Nephritic syndrome Nephritic syndrome is a broad category of glomerular diseases characterized by glomerular hematuria, variable loss of renal function, and hypertension. These features are in contrast to those of nephrotic syndrome, which includes glomerular diseases characterized by severe proteinuria, although there is sometimes overlap of > 1 glomerular disease in the same individual. Nephritic Syndrome, which is characterized by red-to-brown urine, proteinuria, edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema, and acute kidney injury Acute Kidney Injury Acute kidney injury refers to sudden and often reversible loss of renal function, which develops over days or weeks. Azotemia refers to elevated levels of nitrogen-containing substances in the blood that accompany AKI, which include BUN and creatinine. Acute Kidney Injury. The diagnosis is made based on clinical findings in the setting of recent GAS infection. Management is supportive and involves treating the clinical manifestations. The prognosis is generally favorable, especially in children.

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Overview

Definition

Poststreptococcal glomerulonephritis (PSGN) is an immunologically mediated, delayed sequela to clinical pharyngitis Pharyngitis Pharyngitis is an inflammation of the back of the throat (pharynx). Pharyngitis is usually caused by an upper respiratory tract infection, which is viral in most cases. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, and hoarseness. Pharyngitis or skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin infections caused by group A Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus (GAS).

Epidemiology

  • Age at presentation
    • Children between ages 5 and 12
    • Adults over 60 years old
  • Most common cause of acute nephritis worldwide, especially in developing countries
  • 470,000 new cases yearly
  • Annual incidence of 9.5 to 28.5 per 100,000 individuals

Pathophysiology

  • Glomerular immune complex deposition induced by specific nephritogenic strains of group A beta-hemolytic Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus → triggers complement activation and inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body's defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation ( type III hypersensitivity reaction Type III hypersensitivity reaction Type III hypersensitivity, also known as immune complex-mediated hypersensitivity, occurs when antibodies and antigens form immune complexes (ICs) in circulation and deposit in susceptible tissues. The complement system triggers the immune response, leading to leukocyte recruitment and tissue injury. Type III Hypersensitivity Reaction)
  • Nephritogenic strains of GAS never cause rheumatic fever Rheumatic fever Acute rheumatic fever (ARF) is an autoimmune inflammatory process that usually follows Streptococcal pharyngitis. Acute rheumatic fever usually occurs 2-4 weeks after an untreated infection and affects the heart, skin, joints, and nervous system. Rheumatic Fever.

Clinical Presentation

  • Usually occurs more than 10 days after preceding infection by group A beta-hemolytic Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus
    • Strep pharyngitis Pharyngitis Pharyngitis is an inflammation of the back of the throat (pharynx). Pharyngitis is usually caused by an upper respiratory tract infection, which is viral in most cases. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, and hoarseness. Pharyngitis
    • Scarlet fever Scarlet fever Scarlet fever is a clinical syndrome consisting of streptococcal pharyngitis accompanied by fever and a characteristic rash caused by pyrogenic exotoxins. Scarlet fever is a non-suppurative complication of streptococcal infection that is more commonly seen in children. Incidence peaks during the winter and spring in temperate climates. Scarlet Fever
    • Impetigo Impetigo Impetigo is a highly contagious superficial bacterial infection typically caused by Staphylococcus aureus (most common) and Streptococcus pyogenes. Impetigo most commonly presents in children aged 2 to 5 years with lesions that evolve from papules to vesicles to pustules, which eventually break down to form characteristic "honey-colored" crusts. Impetigo 
  • Presentation varies:
    • Asymptomatic, microscopic hematuria (most common)
    • Acute nephritic syndrome Nephritic syndrome Nephritic syndrome is a broad category of glomerular diseases characterized by glomerular hematuria, variable loss of renal function, and hypertension. These features are in contrast to those of nephrotic syndrome, which includes glomerular diseases characterized by severe proteinuria, although there is sometimes overlap of > 1 glomerular disease in the same individual. Nephritic Syndrome
      • Hematuria
      • Proteinuria
      • Edema
      • Oliguria
      • Hypertension
      • Elevated serum creatinine
    • Rapidly progressive glomerulonephritis Rapidly Progressive Glomerulonephritis Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis seen In 0.5% of cases

Diagnosis

Patient’s history:

  • Recent pharyngitis Pharyngitis Pharyngitis is an inflammation of the back of the throat (pharynx). Pharyngitis is usually caused by an upper respiratory tract infection, which is viral in most cases. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, and hoarseness. Pharyngitis 
  • Recent skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin infection

Physical exam findings:

  • Hypertension
  • Edema
  • Oliguria

Lab findings:

  • Recent positive throat or skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin culture for GAS infection
  • Serology tests for:
    • Antistreptolysin-O after pharyngeal infection
    • Antihyaluronidase (AHase)
    • Antinicotinamide-adenine dinucleotidase (Anti-NAD)
    • Antistreptokinase (ASKase) after skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin infection
    • Anti-DNase B after skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin infection
  • If only the antistreptolysin-O titer is used to screen for GAS, it may be falsely negative.
  • Urinalysis
    • Hematuria with RBC casts
    • +/- Proteinuria
  • Other tests
    • ↑ BUN and creatinine
    • ↓ C3 and CH50
    • C2 and C4 usually normal, may be decreased in some cases

Renal biopsy:

  • Indicated if there is significant renal impairment that requires dialysis Dialysis Renal replacement therapy refers to dialysis and/or kidney transplantation. Dialysis is a procedure by which toxins and excess water are removed from the circulation. Hemodialysis and peritoneal dialysis (PD) are the two types of dialysis, and their primary difference is the location of the filtration process (external to the body in hemodialysis versus inside the body for PD). Overview and Types of Dialysis
  • Findings:
    • Light microscopy
      • Diffuse endocapillary proliferation
      • Leukocytic (neutrophilic) infiltration
    • Electron microscopy
      • Primarily subepithelial immune complex deposits
      • Subendothelial deposits in early disease stages
    • Fluorescence microscopy
      • Granular IgG, complement component 3 (C3), glomerular basement membrane (GBM), and mesangium
      • Granular IgA in rare cases
Acute poststreptococcal glomerulonephritis

Acute poststreptococcal glomerulonephritis:
An enlarged glomerulus with global closure of the capillary lumina caused by endogenous predominantly mesangial cell proliferation, infiltrating bloodborne monocytes, and polymorphonuclear leukocytes (H&E staining).

Image: “IgA-dominant acute poststreptococcal glomerulonephritis with concomitant rheumatic fever Rheumatic fever Acute rheumatic fever (ARF) is an autoimmune inflammatory process that usually follows Streptococcal pharyngitis. Acute rheumatic fever usually occurs 2-4 weeks after an untreated infection and affects the heart, skin, joints, and nervous system. Rheumatic Fever successfully treated with steroids: a case report” by Rus RR, Toplak N, Vizjak A, Mraz J, Ferluga D. License: CC BY 2.5

Management

Management

  • Supportive care
  • Antibiotics if the strep infection is still present at the time of diagnosis
    • Penicillin
    • Erythromycin if allergic to penicillin
  • Treat hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension and/or edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema
    • Loop diuretics Loop diuretics Loop diuretics are a group of diuretic medications primarily used to treat fluid overload in edematous conditions such as heart failure and cirrhosis. Loop diuretics also treat hypertension, but not as a 1st-line agent. Loop Diuretics (e.g., furosemide)
    • Sodium and water restriction
  • For hypertensive encephalopathy (rare)
    • Oral nifedipine
    • Parenteral nicardipine
  • Dialysis Indications:
    • Fluid overload that is unresponsive or slow to respond to supportive measures
    • Refractory hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension
    • Evidence of serious compromise of renal function (rapidly rising creatinine)
    • Hyperkalemia Hyperkalemia Hyperkalemia is defined as a serum potassium (K+) concentration >5.2 mEq/L. Homeostatic mechanisms maintain the serum K+ concentration between 3.5 and 5.2 mEq/L, despite marked variation in dietary intake. Hyperkalemia can be due to a variety of causes, which include transcellular shifts, tissue breakdown, inadequate renal excretion, and drugs. Hyperkalemia > 6.5 mEq/L
    • Uremia with BUN of 89–100 mg/dL

Prognosis

  • Usually, there is rapid resolution of symptoms.
    • Hematuria usually resolves in 3 to 6 months.
    • Proteinuria usually resolves in less than 3 months.
    • Children have 95% complete recovery.
    • Adults have 60% complete recovery.
  • Recurrent episodes are rare.
  • Some patients (usually adults) progress to rapidly progressive glomerulonephritis ( RPGN RPGN Rapidly progressive glomerulonephritis (RPGN) is a syndrome of severe glomerular disease with progressive loss of kidney function within weeks to months. Histologically, crescents (the proliferation of epithelial cells and the infiltration of monocytes/macrophages in the Bowman space) are found in the glomeruli and arise from immunologic injury. Rapidly Progressive Glomerulonephritis).
    • Develop hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension
    • Recurrent proteinuria
    • Renal insufficiency up to 10–40 years after diagnosis

Differential Diagnosis

  • C3 glomerulonephropathy: has a clinical presentation that may be indistinguishable from PSGN. The condition also presents with hematuria, hypertension Hypertension Hypertension, or high blood pressure, is a common disease that manifests as elevated systemic arterial pressures. Hypertension is most often asymptomatic and is found incidentally as part of a routine physical examination or during triage for an unrelated medical encounter. Hypertension, proteinuria, and hypocomplementemia, and it may be preceded by an upper respiratory infection. Unlike with PSGN, patients with C3 glomerulonephropathy have persistent urinary abnormalities and hypocomplementemia beyond 4–6 weeks, and they occasionally have a further elevation of serum creatinine.
  • IgA nephropathy IgA nephropathy IgA nephropathy (Berger's disease) is a renal disease characterized by IgA deposition in the mesangium. It is the most common cause of primary glomerulonephritis in most developed countries. Patients frequently present in the second and third decades of life and, historically, with a preceding upper respiratory or GI infection. IgA Nephropathy: presents with glomerulonephritis after a preceding upper respiratory infection, as PSGN can. However, there is usually a shorter time between the infection and nephritic syndrome Nephritic syndrome Nephritic syndrome is a broad category of glomerular diseases characterized by glomerular hematuria, variable loss of renal function, and hypertension. These features are in contrast to those of nephrotic syndrome, which includes glomerular diseases characterized by severe proteinuria, although there is sometimes overlap of > 1 glomerular disease in the same individual. Nephritic Syndrome (less than 5 days) than with PSGN. IgA nephropathy IgA nephropathy IgA nephropathy (Berger's disease) is a renal disease characterized by IgA deposition in the mesangium. It is the most common cause of primary glomerulonephritis in most developed countries. Patients frequently present in the second and third decades of life and, historically, with a preceding upper respiratory or GI infection. IgA Nephropathy can be recurrent, and patients can have preceding episodes of gross hematuria. Management is with ACE inhibitors or angiotensin II receptor blockers, statin therapy for hyperlipidemia, and immunosuppressive therapy. Patients who progress to end-stage renal disease can be treated with dialysis Dialysis Renal replacement therapy refers to dialysis and/or kidney transplantation. Dialysis is a procedure by which toxins and excess water are removed from the circulation. Hemodialysis and peritoneal dialysis (PD) are the two types of dialysis, and their primary difference is the location of the filtration process (external to the body in hemodialysis versus inside the body for PD). Overview and Types of Dialysis or transplantation. 
  • Secondary causes of glomerulonephritis: can be seen with lupus nephritis and Henoch-Schönlein purpura Henoch-Schönlein Purpura Henoch-Schönlein purpura (HSP), also known as immunoglobulin A vasculitis, is an autoimmune small-vessel vasculitis that typically presents as a tetrad of abdominal pain, arthralgia, hematuria, and purpuric rash. Henoch-Schönlein Purpura (HSP). These diseases have extrarenal manifestations specific to the disease process. Henoch-Schönlein purpura Henoch-Schönlein Purpura Henoch-Schönlein purpura (HSP), also known as immunoglobulin A vasculitis, is an autoimmune small-vessel vasculitis that typically presents as a tetrad of abdominal pain, arthralgia, hematuria, and purpuric rash. Henoch-Schönlein Purpura does not have hypocomplementemia. Lupus nephritis has reductions in both complement component 3 and 4, while the latter is usually normal in PSGN. Diagnosis is made by renal biopsy. Management is with ACE inhibitors or angiotensin II receptor blockers, statin therapy for hyperlipidemia, anticoagulation, and immunosuppressive therapy.

References

  1. Kumar V, Abbas AK AK Actinic keratosis (AK) is a precancerous skin lesion that affects sun-exposed areas. The condition presents as small, non-tender macules/papules with a characteristic sandpaper-like texture that can become erythematous scaly plaques. Actinic Keratosis (AK), Aster JC. (2015). Robbins & Cotran Pathologic Basis of Disease. Elsevier Saunders.
  2. Lewis JB & Neilson EG. (2018). Glomerular diseases. In Jameson J., et al. (Eds.). Harrison’s Principles of Internal Medicine, (20th ed.). https://accessmedicine-mhmedical-com.aucmed.idm.oclc.org/content.aspx?bookid=2129&sectionid=192281295
  3. Niaudet P. (2020). Poststreptococcal glomerulonephritis. UpToDate. Retrieved March 10, 2021, from https://www.uptodate.com/contents/poststreptococcal-glomerulonephritis
  4. Rodriguez-Iturbe B & Haas M. (2016). Post-streptococcal glomerulonephritis. https://www.ncbi.nlm.nih.gov/books/NBK333429/

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