Poststreptococcal Glomerulonephritis

Acute glomerulonephritis is a disease characterized by the sudden appearance of edema, hematuria, proteinuria, and hypertension. It is a representative disease of acute nephritic syndrome in which inflammation of the glomerulus is manifested by proliferation of cellular elements secondary to an immunologic mechanism (see the following image).

A schematic representation of the proposed mechanism for acute poststreptococcal glomerulonephritis (APSGN). C = Activated complement; Pl = Plasmin; NAPlr = Nephritis-associated plasmin receptor; SK = Streptokinase; CIC = Circulating immune complex.

Acute poststreptococcal glomerulonephritis (APSGN) results from an antecedent infection of the skin or throat caused by nephritogenic strains of group A beta-hemolytic streptococci. The concept of nephritogenic streptococci was initially advanced by Seegal and Earl in 1941, who noted that rheumatic fever and acute poststreptococcal glomerulonephritis (both nonsuppurative complications of streptococcal infections) did not simultaneously occur in the same patient and differ in geographic location. Acute poststreptococcal glomerulonephritis occurs predominantly in males and often completely heals, whereas patients with rheumatic fever often experience relapsing attacks.

The M and T proteins in the bacterial wall have been used for characterizing streptococci. Nephritogenicity is mainly restricted to certain M protein serotypes (ie, 1, 2, 4, 12, 18, 25, 49, 55, 57, and 60) that have shown nephritogenic potential. These may cause skin or throat infections, but specific M types, such as 49, 55, 57, and 60, are most commonly associated with skin infections. However, not all strains of a nephritis-associated M protein serotype are nephritogenic. In addition, many M protein serotypes do not confer lifetime immunity. Group C streptococci have been responsible for recent epidemics of APSGN (eg,Streptococcus zooepidemicus). Thus, it is possible that nephritogenic antigens are present and possibly shared by streptococci from several groups.

In addition, nontypeable group A streptococci are frequently isolated from the skin or throat of patients with glomerulonephritis, representing presumably unclassified nephritogenic strains.^[7] The overall risk of developing acute poststreptococcal glomerulonephritis after infection by these nephritogenic strains is about 15%. The risk of nephritis may also be related to the M type and the site of infection. The risk of developing nephritis infection by M type 49 is 5% if it is present in the throat. This risk increases to 25% if infection by the same organism in the skin is present.

Poststreptococcal GN (Introduction)

Usually occurs 10 days after pharyngitis and 14days after skin infection(not synpharyngitic)Fallen incidence in US, butcommon in some ruralareas, poor hygieneplaces, and tropical countries .Occurs more often in males and children


Poststreptoccal GN (nephritic strains)
>Known nephritic strainsinclude M types 1, 2, 4,12, 18, 25, 49, 55, 57, 60 Many proposed mechanisms: Molecular mimickry vs. autoimmunevs. polyclonal activation of B lymphocytesRepeat infections are not common as immunity is type specific and not usually transient


Clinical Presentation
Most patients have milder diseaseClassically, presents with overt nephritic syndrome and oliguric ARF. Symptoms can include gross hematuria(100% microscopic), HA, htn (60-80%),hypervolemia, and edema (80-90%)


Nephritic urinary sediment –dysmorphic RBCs, redcell casts, leukocytes,subnephrotic proteinuria . Nephrotic-range proteinuria not common.

Labs
Serum Cr can be commonly elevated at presentation, though
mildC3 and CH50 decreased w/in 2 weeks C4 usually normal (complement level usually normal within 6-
8 weeks)Most patients have directed Ab, such as ASO, anti-DNAse B,
etc,Serum IgG and IgM increased in 80% and returns to normal in 1-2 months
Polyclonal cryoglobulinemia in 75%.

Light Microscopy

On light microscopy,
usually see diffuse
proliferative GN











Course

>Irreversible Renal Failure rare – less than 1 % in
children, slightly higher in adults
>Resolution usually quick, plasma Cr usually
returns to previous levels by 3-4 weeks
>Hematuria resolves usually within 3-6 months,
proteinuria falls at a slower rate
>Some patients experience htn, recurrent
proteinuria, and renal insufficiency 10-40 yrs after
> 20% of adults may have some degree of
persistent proteinuria and or compromise of GFR
1 year out.


Treatment

>Eliminate strep infxn with abx
>Supportive therapy
>Diuretics and antihypertensives to control
bp and extracellular fluid volume

Rajendra Bhimma, MB, ChB, MD, DCH (SA), FCP (Paeds)(SA), MMed (Natal)  Associate Professor of Pediatrics, Principal Specialist, Department of Pediatrics and Child Health, Nelson R Mandela School of Medicine, University of KwaZulu-Natal, South Africa 

Rajendra Bhimma, MB, ChB, MD, DCH (SA), FCP (Paeds)(SA), MMed (Natal) is a member of the following medical societies: American Association for the Advancement of Science, International Pediatric Transplant Association, International Society of Nephrology, South African Medical Association, South African Paediatric Association, and South African Transplant Society 

Disclosure: Nothing to disclose.

A diet based on starchy foods such as rice and pasta; with plenty of fruit and vegetables; some protein-rich foods such as meat, fish and lentils; some milk and dairy foods; and not too much fat, salt or sugar, will give you all the nutrients you need.

When it comes to a healthy diet, balance is the key to getting it right. This means eating a wide variety of foods in the right proportions, and consuming the right amout of food and drink to achieve and maintain a healthy body weight.

Most adults in England are either overweight or obese. That means many of us are eating more than we need, and should eat less. And it's not just food: some drinks can also be high in calories. Most adults need to eat and drink fewer calories in order to lose weight, even if they already eat a balanced diet.

Food groups

• Fruit and vegetables.
• Starchy foods, such as rice, pasta, bread and potatoes. Choose wholegrain varieties whenever you can.
• Meat, fish, eggs and beans.
• Milk and dairy foods.
• Foods containing fat and sugar.