What is the relationship between Streptococcus A (Strep A) infection and glomerulonephritis (post-streptococcal glomerulonephritis)?

From the Guidelines

Strep A glomerulonephritis, also known as post-streptococcal glomerulonephritis (PSGN), is an immune-mediated kidney inflammation that typically resolves on its own within weeks to months with supportive care. The treatment primarily involves supportive measures, including sodium restriction (less than 2 grams daily) and diuretics like furosemide (20-40 mg daily) if edema is present, as well as blood pressure control using ACE inhibitors like lisinopril (starting at 5-10 mg daily) 1. For the acute infection, antibiotics such as penicillin (500 mg orally twice daily for 10 days) or amoxicillin (500 mg three times daily for 10 days) are recommended to eradicate any remaining streptococcal bacteria, though they do not alter the course of the glomerulonephritis itself 1.

Key Considerations

• For penicillin-allergic patients, azithromycin (500 mg on day 1, then 250 mg daily for 4 more days) or clindamycin (300 mg three times daily for 10 days) are alternatives 1.
• Monitoring kidney function, blood pressure, and urinalysis for 6-12 months is recommended to ensure resolution 1.
• The condition results from immune complexes forming when antibodies against streptococcal antigens cross-react with kidney tissues, causing inflammation in the glomeruli.

Treatment Approach

• The primary goal is to provide supportive care and manage symptoms while the condition resolves on its own.
• Antibiotics are used to treat the underlying streptococcal infection, but they do not directly affect the glomerulonephritis.
• Blood pressure control and sodium restriction are crucial to manage the condition and prevent further kidney damage.

Recent Guidelines

• The KDIGO 2021 clinical practice guideline for the management of glomerular diseases provides an updated approach to managing glomerulonephritis, including post-streptococcal glomerulonephritis 1.
• The guideline emphasizes the importance of supportive care, blood pressure control, and monitoring kidney function in the management of glomerulonephritis.

From the Research

Definition and Causes of Strep A Glomerulonephritis

• Strep A glomerulonephritis, also known as post-streptococcal glomerulonephritis (PSGN), is an immune-complex mediated inflammation that occurs after an infection with group A beta-hemolytic streptococci (GABHS) 2.
• The infection can occur through the skin (impetigo) or throat (pharyngitis) and is characterized by the proliferation of cellular elements called nephritogenic M type 2.
• The formation of an immune complex of antigen-antibody and complement system takes place after the infection, which deposits in the glomeruli and leads to inflammation 2.

Diagnosis and Management of Strep A Glomerulonephritis

• PSGN is diagnosed by laboratory tests like microscopy and urinalysis, and imaging studies can be used to assess possible complications such as pulmonary congestion and chronic kidney disease 2.
• The management of PSGN is symptomatic, and if left untreated, the patient may develop chronic kidney disease 2.
• Timely antimicrobial treatment of GABHS tonsillopharyngitis can prevent suppurative complications and rheumatic fever, but it does not prevent acute poststreptococcal glomerulonephritis 3.

Prevention of Strep A Glomerulonephritis

• The main way to prevent PSGN is to treat GABHS infections with good coverage of antibiotic therapy to prevent the development of complications 2.
• Different antibiotic treatments, such as penicillin, cephalosporins, and macrolides, have been compared in terms of their efficacy in treating GABHS tonsillopharyngitis, but the evidence is uncertain regarding their effectiveness in preventing PSGN 4.
• Amoxicillin may be superior to penicillin for bacteriologic and clinical cure of GABHS tonsillopharyngitis, but the evidence is limited 5.

Epidemiology and Control of Group A Streptococcus Infection

• Group A Streptococcus (GAS) infection is a significant public health concern, with fluctuating global epidemiology characterized by the emergence of new GAS clones 6.
• The development of safe and effective GAS vaccines is a priority, and the World Health Organization (WHO) has outlined preferred vaccine characteristics 6.