LOWER URINARY TRACT INFECTION AND CYSTITIS

LOWER URINARY TRACT INFECTION AND CYSTITIS:

Isolated infection
A single episode of lower tract infection occurs frequently in females and is rarely complicated.
Recurrent infection
Recurrent infection may be associated with an underlying predisposing cause or may be a result of bacterial resistance.
Repeated attacks of UTI in women, or a single attack in a man or a child of either sex, should always be followed by investigation to discover and treat the cause; sometimes, however, no cause can be found. Asymptomatic bacteriuria is common and investigation may fail to demonstrate any underlying cause.

Predisposing causes of urinary tract infection
• Incomplete emptying of the bladder, secondary to bladder outflow obstruction, a bladder diverticulum, neurogenic bladder dysfunction or decompensation of the detrusor muscle.
• A calculus, foreign body or neoplasm.
• Incomplete emptying of the upper tract, dilatation of the ureters associated with pregnancy, or vesicoureteric reflux.
• Oestrogen deficiency, which may give rise to lowered local resistance.
• Colonisation of the perineal skin by strains of Escherichia coli expressing molecules that facilitate adherence to mucosa.
• Diabetes.
• Immunosuppression.
Avenues of infection
Ascending infection from the urethra is the most common route. The organisms originate in the bowel, contaminate the vulva and reach the bladder. The passage of urethral instruments may cause infection in either sex, especially when the bladder contains residual urine.
Other routes are less common and include descending infection from the kidney(tuberculosis), haematogenous spread, lymphogenous spread and spread from adjoining structures (fallopian tube, vagina or gut).