True bacteriuria is defined as quantitative culture of bacteria ≥10^5/ml in the middle segment of urine or qualitative culture of bacteria in suprapubic cystocentesis urine on both occasions. The primary etiology of true bacteriuria is urinary tract infection. Clinical examination of true bacteriuria due to urinary tract infection: 1. Acute simple cystitis The onset is sudden and the onset is mostly associated with sexual activity in female patients. The main manifestations are bladder irritation signs, namely urinary frequency, urinary urgency, painful urination, discomfort in the bladder area or perineum and burning sensation in the urethra; urinary frequency varies in degree, and in severe cases, urge incontinence can occur; cloudy urine, white blood cells in the urine, terminal hematuria is common, sometimes the whole hematuria, and even see blood clots discharged. There are usually no obvious symptoms of systemic infection, and the body temperature is normal or there is low fever. 2. Acute simple pyelonephritis (1) Urinary symptoms include bladder irritation such as urinary frequency, urinary urgency and pain; hematuria; back pain on the affected side or bilaterally; significant pressure pain or percussion pain on the affected spinal rib angle, etc. (2) Symptoms of systemic infection such as chills, high fever, headache, nausea, vomiting, loss of appetite, etc., often accompanied by elevated blood white blood cell count and increased blood sedimentation. 3, asymptomatic bacteriuria asymptomatic bacteriuria is an insidious urinary tract infection, mostly seen in elderly women and pregnant women, patients do not have any symptoms of urinary tract infection, the incidence increases with age. 4.Complex urinary tract infection The clinical manifestations of complex urinary tract infection vary greatly, often accompanied by other diseases that increase the risk of acquiring infection or treatment failure, which may or may not be accompanied by clinical symptoms (such as urinary frequency, urgency, painful urination, difficulty in urination, pain in the low back, pressure pain in the spinal rib angle, pain in the suprapubic area and fever). Complex urinary tract infections are often accompanied by other diseases, such as diabetes mellitus and renal failure; they also lead to more sequelae, the most serious and fatal conditions including urinary sepsis and renal failure, which can be classified as acute and chronic, reversible and irreversible.