Cystitis is one of the most common urinary tract infections, both acute and chronic, caused by bacterial infections, with E. coli as the pathogenic bacteria. The pathway of bacterial invasion is an upstream infection, and the second is a bloodstream infection. Acute cystitis is mostly due to an upstream infection. The actual fact is that you can find a lot of people who are not able to get a good deal on a lot of things. 1, bad habits unclean sex or frequent sex, do not pay attention to personal hygiene, sharing towels, smoking and drinking, often eat spicy food, sedentary and other bad habits can lead to urinary tract infection, thus causing cystitis. 2, drink less water, hold urine more water, urinate regularly, is conducive to flush the male bladder, the bacteria out of the body, to reduce the chances of cystitis infection. The female urethra is shorter than the male, usually only about 4-6cm, even shorter after being propped up by urine, bacteria can easily enter, but also make the urethral mucosa secretion of bactericidal substances to reduce the function. Holding urine for a long time will allow bacteria to breed in the urethra, and without the flushing of urine, bacteria retrograde to the bladder causing acute inflammation. Especially people with colds or poor body resistance are more likely to be sick. 3, immunity decline In the decline of their immunity, bacterial virulence increases, and the possibility of bladder infection increases. The normal bladder has a strong resistance to bacteria, it is difficult for bacteria to invade the bladder wall through the uroepithelium, and bacteria in the distal urethra generally cannot enter the bladder, even if they enter the bladder, under normal circumstances, they are driven out of the body with the excretion of urine, resulting in bacteria in the bladder can not stay, reproduce and cause infection.