Bacteriuria is a mid-urine specimen collected under aseptic technique after cleaning the vulva, such as smears where bacteria are seen in every high-powered field of view or culture colonies with counts exceeding 100,000 per milliliter. Usually the urine of normal people contains bacteria, mainly because the kidneys excrete toxins from the body. Therefore, in some patients with pyelonephritis, bacteriuria can occur because of impaired kidney function, so many patients with pyelonephritis are very worried. The possible causes of bacteriuria in patients with pyelonephritis are: 1. The most common etiology is the use of anti-inflammatory drugs and chemotherapy to inhibit the activity of bacteria. 2. Obstruction of the ureter on the affected side prevents the bacteria from being excreted with the urine. 3, Urine pH below 5.0 or highly diluted urine is not conducive to bacterial growth. 4, Rapid urine flow so that bacteria do not have the opportunity to multiply, or certain bacteria grow more slowly or are less likely to multiply. 5. Chronic pyelonephritis is a sterile disease that begins with bacterial infection and later the bacteria disappear while the infection is maintained by the persistence of bacterial toxins or by autoimmune mechanisms.