Pediatric legionellosis nephritis

　　1. Etiology

　　Legionella is an aerobic Gram-negative bacillus, among which LD1, 4, and 6 types are more important. This bacterium can produce beta-lactamase, and Legionella can secrete zinc-containing metalloproteinases, causing tissue dissolution and destruction, which can form cavities. In addition, this bacterium can also release toxins with pathogenic effects.

　　2. Pathogenesis

　　The pathogenesis of renal damage is not yet fully understood and may be related to the direct invasion of the local area by endotoxins or bacteria, or to immune reaction injury. Coagulation factors, complement system, vasoactive amines, and glomerulonephritis are related to the onset of the disease. Some reports suggest that renal damage is related to DIC. Most authors believe that acute tubular necrosis and acute interstitial nephritis are the main reasons for acute renal failure in this disease. There are also reports of individual cases confirmed as rapidly progressive glomerulonephritis by histopathology, and autopsies of cases with pyelonephritis with abscess formation.

　　Serious cases of legionellosis can lead to symptoms such as lung abscess, pleurisy, pericarditis, respiratory failure, heart failure, shock, DIC, and others. Patients with renal legionellosis may present with oliguria or anuria, which can develop into acute renal failure.

　　23, General manifestations:The typical clinical manifestation of legionellosis is an acute pulmonary infection with symptoms such as fever, cough, and chest pain.

　　21, Other systems:Symptoms may include abdominal pain, diarrhea, gastrointestinal bleeding, and other symptoms of the digestive system. Some cases may have symptoms such as headache, irritability, drowsiness, and coma, which are neurological symptoms.

　　19, Renal damage:Half of the patients have proteinuria, some show nephrotic syndrome-like manifestations, some have microscopic hematuria, severe cases may present with oliguria or anuria, which can develop into acute renal failure and show corresponding clinical manifestations.

　　15, There are currently no effective preventive measures:

　　14, Drinking water disinfection by adding chlorine or boiling can kill this bacterium.

　　13, The air conditioning system should be closed and disinfected and cleaned; for the water supply system, wet equipment, sprayers, and other equipment should be managed for hygiene to control outbreaks.

　　12, Immune vaccines are under development.

　　9, General examination The peripheral blood leukocyte count can be within the normal range or slightly elevated, with moderate acceleration of erythrocyte sedimentation rate, and hyponatremia is relatively common.

　　8, Urinalysis examination Abnormalities in urinalysis are observed in this condition, including proteinuria and microscopic hematuria.

　　7, Renal failure patients may have azotemia and other indicators of renal function impairment, including reduced creatinine clearance and a filtration sodium excretion fraction higher than normal.

　　6, Respiratory secretions (sputum or bronchial aspirates) examination by Gram staining cannot detect a large number of dominant bacterial populations, only a small number of neutrophils.

　　5, Culturing legionella bacteria is not very significant for early diagnosis. Sputum, bronchial aspirates, bronchoscope lavage fluid, pleural effusion, or lung tissue homogenate can be inoculated into Mueller-Hinton medium, adding 0.025% ferric pyrophosphate and 0.04% L-cysteine, or inoculated into charcoal yeast extract agar medium. It is currently believed that the latter has a positive rate of 60% to 70%.

　　4, Serological tests using indirect immunofluorescence have high sensitivity and specificity. A fourfold increase in the titer of double serum samples or a titer of ≥1:256 in a single serum sample can be used for diagnosis.

　　Delicious foods are often high in protein, purines, potassium, and phosphorus, and these are precisely the types of foods that patients with various kidney diseases should consume as little as possible. It is well known that the kidneys are organs responsible for secreting metabolic waste, regulating water, electrolytes, and acid-base balance. Once the kidneys are affected by disease, these physiological functions will be weakened to varying degrees. If a large amount of high-protein, high-purine, high-potassium, and high-phosphorus foods are consumed, exceeding the secretion function of the kidneys, the kidneys will be overwhelmed, which is likely to trigger or exacerbate kidney damage, leading to increased blood creatinine, hyperuricemia, hyperkalemia, hyperphosphatemia, and a series of complications, harming physical health. In addition, excessive intake of water (such as various beverages, soups, and stews), exceeding the secretion function of the kidneys, is likely to trigger or exacerbate water and sodium retention, leading to edema and hypertension, which is almost due to increased cardiac workload leading to heart failure.

　　I. Treatment

　　1. Treatment for pathogenic bacteria:Erythromycin is the first choice, about 2g per day for adults, and children should be divided into 4 times according to the conventional dose. Oral administration is poor, and intravenous infusion should be given. The course of treatment is 3 weeks. Generally, the body temperature drops and the symptoms of the whole body and respiratory tract improve within 48 hours after treatment. If the course of treatment is less than 2 weeks, there is a possibility of recurrence or prolonged recovery period. If the efficacy of erythromycin is not satisfactory or the condition is severe, rifampicin and isoniazid can be added as adjuvant therapy. Rifampicin is taken in a single dose of 600-900mg per day, or divided into two doses for oral administration. Penicillins, aminoglycosides, and cephalosporins have no significant efficacy for this disease.

　　2. Symptomatic and supportive therapy:Cardiac strengthening, diuretics, protecting renal function, preventing and treating infection. In addition, general treatment is also very important for this disease. The application of artificial respiration in respiratory failure, vasoactive drugs and other antishock measures in shock, are all important treatment measures.

　　3. For kidney damage:Steroid corticosteroids and immunosuppressants should be given when necessary, and attention should be paid to maintaining water and electrolyte balance and correcting metabolic acidosis in patients with acute renal failure. Hemodialysis treatment is needed for severe patients with acute renal failure.

　　II. Prognosis

　　The mortality rate of legionnaires' disease is about 15%, which increases with age, and is also high in patients with underlying diseases or immune deficiencies. The cause of death is mostly respiratory failure, followed by shock and acute renal failure. The mortality rate of kidney disease in legionnaires' disease is high. Early diagnosis and active treatment can significantly reduce the mortality rate. If it occurs in patients with low immunity, such as in renal dialysis, renal transplantation, malignant tumors, and patients receiving immunosuppressants, the prognosis is poor. If early diagnosis and effective treatment are given, the mortality rate can be reduced.