Urinary tract infection is an inflammation of the urinary tract caused by the multiplication of a large number of bacteria and other microorganisms in the urinary tract, which may or may not have clinical symptoms such as frequent urination, urgency, painful urination, etc. In severe cases, chills and high fever may occur, even causing life-threatening sepsis, which is a common and frequent disease, and many patients have serious health and quality of life problems due to recurrent urinary tract infections. More than 95% of urinary tract infections are caused by a single bacterium. In 90% of outpatients and about 50% of inpatients, the pathogenic bacteria are Escherichia coli, mostly seen in asymptomatic bacteriuria or uncomplicated urinary tract infections; Aspergillus, Bacillus pneumoniae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Streptococcus faecalis, etc. are seen in re-infection, indwelling catheter, and urinary tract infections with complications; Candida albicans, new Cryptococcus infections are mostly seen in diabetes and patients using glucocorticoids and Although viral and mycoplasma infections are rare, they tend to increase gradually in recent years. Multiple bacterial infections are seen in indwelling catheters, neurogenic bladder, stones, congenital malformations and vaginal, intestinal and urethral fistulas. Although normal urine is sterile, the external urethra hosts normal flora, so the general urine pathogen examination has no clinical significance. A urinary tract infection can be diagnosed when the clean middle urine bacterial count exceeds 100,000 bacteria/ml. Infection is possible when the colony count is between 5×10,000-100,000. When the colony count is <5×10000, there is no infection. The main function of urine culture is to perform bacteriological culture of urine to clarify the type and number of bacteria causing urinary tract infection and to clarify which antibacterial drugs are effective against the bacteria through drug sensitivity testing. Based on the results of the urine culture and the patient's age, drug allergy, liver and kidney function, the doctor selects the appropriate drug, the appropriate dosage and medication method for treatment, so that the patient can recover as soon as possible. Many doctors and patients ignore the importance of urine culture and do not know what the causative bacteria are in different types of patients and what antibacterial drugs they are sensitive to, and often use drugs based on "experience", resulting in unsatisfactory treatment, increased patient suffering, and even threatening the lives of patients due to delayed treatment. Therefore, it is recommended that doctors and patients do not forget to do a urine culture before treating urinary tract infections. Bacteria are normally present around the urethral orifice, which must be washed clean, otherwise the bacteria cultured are not the pathogenic bacteria of infection in urine, but contaminated bacteria. Please follow the following principles when keeping urine: 1. It is best to take the first urine in the early morning; 2. Use a sterile covered container prepared by the hospital; 3. Wash the female vulva with soap and water first, then wash it with water, then urinate, discard the front part of the urine, keep about 10 ml of the middle part of the urine in the container, cover it immediately and send it for examination as soon as possible, do not exceed 1 hour, otherwise, store it temporarily in the refrigerator at 4°C. If Neisseria gonorrhoeae infection is suspected, it should be immediately Inoculation, can not be stored in the refrigerator. Men should flip the foreskin and wash, again with soap and water first, then with water; 4. If collection of the middle urine cannot avoid contamination, catheterization and cystocentesis can also be used, but they are more troublesome and prone to retrograde infection; 5. It is best to perform bacterial culture before medication or 1-2 days after stopping medication; 6. Do not mix antiseptic or disinfectant in the urine. False-positive or false-negative results in urine culture, generally accounting for 1/3-2/3. Factors affecting the results of urine culture are summarized as follows 10: 1, the collection of substandard urine in the middle, vulva disinfection has a great impact on urine culture, too much disinfectant and mixed into the urine specimen, which inhibits the growth of bacteria and false-negative results. 2, urine collection should be fresh and should not be left for more than 1 hour, otherwise bacteria will increase greatly and false positives will occur. 3, urine culture before the use of antibacterial drugs, urine bacterial development is inhibited, can appear false negative. 4, the short residence time of urine in the bladder less than 6 hours,, the bacteria do not have enough time to multiply, or drink too much water, diluting the bacteria in the urine, which affects the correctness of the results. 5, bacterial infection lesions and urinary tract is not accessible. For example, in the early stage of hemorrhagic pyelonephritis or urinary tract obstruction, the patient has obvious symptoms of urinary tract infection, but the urine bacterial culture is negative. 6, The acidity and alkalinity of urine are not suitable for bacterial growth. 7, Different strains of bacteria have an effect on the colony count. 8, high nutritional requirements of pathogenic bacteria, not easy to grow on the culture medium; errors in inoculation techniques, can also affect the results. 9, urinary tract infection of the discharge of bacteria can be intermittent, such as chronic pyelonephritis without acute symptoms, urine culture can be negative, but in its acute attack, urine culture is often positive. 10. L-type bacteria can only grow in hypertonic media and cannot be cultured in general media. It has been estimated that about 20% of negative urine cultures in patients with pyelonephritis are associated with L-type bacteria. It can be seen that a negative urine culture should be analyzed for its causes and should be combined with clinical diagnosis and treatment. A negative urine culture does not exclude urinary tract infections, which sometimes have to be repeated several times. Drug sensitivity test report S, I, R refers to what: Ssusceptible, refers to bacteria sensitive to antibacterial drugs, the use of conventional dose of the average blood concentration of more than 5 times the MIC, with conventional dose is usually effective; Iintermediate, refers to bacteria moderately sensitive to antibacterial drugs, the average blood concentration of conventional dose equal to or slightly higher than the MIC, need to use high dose or to Rresistance means that the bacteria are resistant to a certain antimicrobial drug, and the MIC of the drug against the bacteria is higher than the blood concentration when the conventional dose is applied, and treatment with conventional dose is usually ineffective.