Urinary tract infection (UTI) is a common condition, accounting for 1 to 3% of all primary care consultations in the United Kingdom. It affects patients of both sexes and all ages. The commonest organism causing uncomplicated community-acquired bacterial UTI is Escherichia coli.
The occurrence and course of a UTI is influenced by the integrity of the host defence and by bacterial virulence factors. Disruption of the highly specialized transitional cell epithelium which lines the urinary tract, incomplete bladder emptying, anatomical abnormalities, and the presence of a foreign body, such as a urinary catheter, can all contribute to disruption of the host defence and increase the likelihood of infection. Sexual intercourse, use of condoms, and use of spermicides all increase the risk, and genetic factors influence the susceptibility of some people, e.g. girls with the P1 blood group are at increased risk of acute pyelonephritis. Bacterial characteristics that determine their ability to cause infection include specific mechanisms to adhere to the uroepithelium (‘pili’ or ‘fimbrias’ in the case of certain ...