What causes cystitis?

Cystitis is a bacterial infection of the bladder. It starts when bacteria called Escherichia coli (E. coli) attach successfully to the mucosal surface of the bladder lining. This is not the mutant E. coli that causes potentially lethal gastrointestinal infections, but one found in small quantities in a normal intestinal tract. Although it is harmless in these small quantities in the intestinal tract, it gets out of control if it moves to the bladder and urinary tract, multiplying and becoming an undesirable infection.

The attachment of these bacteria to the bladder lining is made easier by fibres on the wall of the bacteria, which can grab onto the cells lining the urinary tract. One of the reasons that it is thought that cranberry reduces the chances of developing a urinary tract infection is that it makes it harder for these fibres to adhere to the urinary tract surfaces.

There can be other factors behind recurrent infections. One factor is that bacteria find it harder to infect the bladder when urine is a little acidic rather than alkaline. Having plenty of fresh fruit and vegetables in the diet and avoiding caffeine, highly processed foods (or junk food) and refined sugar reduces the likelihood of overly alkaline urine. Drinking plenty of water daily also helps, as very concentrated urine is far more irritating to the wall of the bladder, which is then less able to resist infection.

Another factor that can contribute to recurrent cystitis is poor immune function, as the immune system should ideally be able to counter bacteria before they cause infections.