Acute glomerulonephritis caused by streptococcal infection

　　This disease is caused by infection with Streptococcus hemolyticus type A, and the strain of hemolytic streptococcus that causes glomerulonephritis often varies with the epidemiological situation. There is a so-called 'nephritogenic streptococcus', generally with type 12 of group A being the most common, other types such as 1, 4, 18, 25, 41, 49, etc., while types 2, 49, 55, 57, and 60 are often associated with skin abscesses and glomerulonephritis. Whether acute glomerulonephritis occurs and the severity of the lesion are not related to the severity of streptococcal infection. People who have had post-streptococcal glomerulonephritis have a type-specific, permanent, and protective immunity to M protein, so they rarely have a recurrence.

　　Common complications of post-streptococcal acute glomerulonephritis in children mainly include the following:

　　1. Acute congestive heart failure

　　Acute left heart failure can become the initial symptom of pediatric acute glomerulonephritis. If not diagnosed and treated in a timely and correct manner, it can lead to rapid death in children.

　　2. Hypertensive encephalopathy

　　Common symptoms of the disease include severe headache and喷射状呕吐 followed by visual impairment, confusion, drowsiness, and can occur paroxysmal convulsions or seizures such as convulsions and loss of consciousness.

　　3. Acute renal failure

　　During the acute phase of acute glomerulonephritis, there is a large amount of proliferation of glomerular mesangial cells and endothelial cells, narrowing of capillaries, and intravascular thrombosis. Patients may present with oliguria or anuria, with a large amount of renal toxic substances such as urea nitrogen retained in the blood, which can lead to acute renal failure or uremia.

　　4. Secondary bacterial infection

　　Due to reduced overall resistance, acute glomerulonephritis is prone to secondary infections, the most common being pulmonary and urinary tract infections. Once infection occurs, it should be actively treated; otherwise, it can lead to the aggravation of the original disease. At the same time, attention should be paid to the nephrotoxicity of the antibiotics used to be as small as possible to avoid increasing the burden on the kidneys.

　　Currently, it is believed that the disease is caused by an immune response after infection, and the pathological changes of acute glomerulonephritis vary with the course of the disease and the severity of the lesions. Typical cases may present with symptoms such as edema, hematuria, and proteinuria after streptococcal infection in the pharynx, skin, and other areas, and diagnosis is generally not difficult.

　　To prevent this disease, it is necessary to enhance physical fitness, improve the body's defense function, maintain environmental hygiene, and reduce upper respiratory tract infections, pharyngitis, tonsillitis, and other diseases. Attention should be paid to cleanliness and reduce the occurrence of pyoderma. In the event of the aforementioned diseases, active treatment should be sought, and measures such as clearing chronic infection foci such as recurrent tonsillitis and sinusitis should be adopted. Children living in collective settings can use antibiotics for prevention to reduce the incidence during outbreaks of streptococcal infection. In recent years, the incidence of acute glomerulonephritis has decreased significantly. 

　　Acute glomerulonephritis after streptococcal infection generally requires the following examinations for diagnosis:

　　1. Two to three weeks after upper respiratory or skin infection, hematuria, proteinuria, oliguria, edema, hypertension, and even azotemia may occur.

　　2. Complement C3 level decreases acutely and recovers within 6-8 weeks, the titer of streptococcal 'O' antibody (ASO) increases, blood sedimentation rate accelerates, and urine specific gravity increases.

　　3. Ultrasound shows uniform enlargement of both kidneys.

　　4. Renal biopsy shows diffuse mesangial proliferative glomerulonephritis.

　　A reasonable diet is necessary for better recovery from the disease. So, how should patients with this disease eat? The following will introduce this to everyone.

　　1. Limit protein intake

　　Acute glomerulonephritis due to streptococcal infection occurs 3 to 6 days after onset, with a decrease in glomerular filtration rate, which may cause transient azotemia. Therefore, protein intake should be restricted, and within the restricted range, efforts should be made to choose high-quality protein foods.

　　2. Low-Salt and Low-Sodium Diet

　　Patients with edema and hypertension should adopt a low-salt, salt-free, or low-sodium diet. Generally, less than 3 grams of salt or 10 to 15 milliliters of soy sauce should be used per day, and all foods containing a lot of salt should be avoided.

　　3. Limit High-Potassium Foods

　　When oliguria, anuria, or elevated blood potassium levels occur, the intake of vegetables and fruits rich in potassium should be limited.

　　4. Limit Fluid Intake

　　The intake of fluids should be controlled according to the amount of urine excreted each day. The general method of supplementation is to add an additional 500 to 1000 milliliters of fluid to the amount of urine excreted the previous day. If the urine output is low or accompanied by edema, the daily fluid intake should not exceed 1000 milliliters.

　　Most acute glomerulonephritis following streptococcal infection can be self-healing, therefore, for mild cases, it is not necessary to use too much medication. Generally, the following measures can be taken:

　　1. Rest

　　Rest is very important for preventing the aggravation of symptoms and promoting the improvement of the disease. There is no consensus on whether patients with significant edema and hypertension should rest in bed completely, but if slight activity causes symptoms and urine routine abnormalities to worsen, then bed rest is still recommended. It should be avoided to be exposed to cold and dampness, in order to prevent cold from causing spasm of renal arterioles, aggravating renal ischemia.

　　2. Diet

　　At the initial stage of the disease, dietary control is very important. In principle, a low-salt diet should be provided and water intake should be restricted. If the blood pressure is very high and edema is significant, a salt-free diet should be given, and the daily fluid intake should be limited to 1000ml or less. For those with anuria, treatment should be given according to acute renal failure. The daily protein intake for adults should be 30 to 40g, or calculated as 0.6g/kg/day, in order to avoid increasing the burden on the kidneys.

　　3. Control Infection

　　For precursors of infections that still exist in the body, such as pharyngitis, tonsillitis, impetigo, sinusitis, otitis media, and others, active treatment should be sought. Since the foci of precursor infections are sometimes hidden and difficult to detect, even if no clear focus of infection can be found, it is generally recommended to use penicillin (for those allergic to penicillin, use lincomycin or erythromycin) for routine treatment for 10 to 14 days to prevent antigens from continuing to invade the body, in order to prevent the recurrence or chronic development of glomerulonephritis. It should be avoided to use antibiotics that are harmful to the kidneys.