Serious symptoms of bacterial infection vary according to the site of infection, with different clinical manifestations, such as respiratory tract, digestive tract, urinary tract, brain, blood system infections and so on. 1. Respiratory tract infection: severe manifestations include high fever or high fever that does not go away may be accompanied by chills, cold and clammy skin all over the body, shortness of breath, cyanosis, etc. On auscultation, the lungs may be full of wet rales, and CT of the lungs may show wet sounds. Auscultation is full of pulmonary wet rales, and CT of lungs may show multiple flaky hyperdense shadows in both lungs. 2. Bacterial infection of the digestive tract: blood in the stool, abdominal pain, or high fever, vomiting, inability to eat. 3. Urinary tract bacterial infection: a large number of white blood cells, pus cells, red blood cells, etc. can be seen in the urine, and symptoms of urinary tract infection such as frequent urination, urgency of urination, pain of urination, burning sensation of the urethra, etc., and at the same time, there can be a high fever or obvious percussive pain in the kidney area. 4. Bacterial infection of the brain: the performance may have severe headache, vomiting and neck straightening, and in severe cases, there may be consciousness disorder, coma and other symptoms. If lumbar puncture is performed to observe the cerebrospinal fluid, turbid cerebrospinal fluid with purulent changes will be seen. 5. Blood system infection: in severe cases, there will be sepsis, septicemia, etc., often accompanied by fever, decreased blood pressure, increased heart rate, circulatory failure, and so on. It can cause multi-organ failure such as liver and kidney insufficiency, hematopoietic dysfunction and so on. When bacterial infection occurs, patients should go to the hospital in time for relevant examinations such as blood routine, drug sensitivity test, etc., symptomatic treatment to prevent aggravation of the condition and life-threatening; during the period of bacterial infection, pay attention to rest, strengthen the nutrition, and improve the body’s resistance; do not smoke and drink, avoid exertion, and inform the doctor in time to receive systematic treatment when uncomfortable symptoms occur.