Dysuria occurs each year in approximately 20 percent of women between 24 and 64 years of age, half of whom come to medical attention. Recurrence may be from relapse or reinfection. Relapse in either sex is caused by reappearance of the same organism from a sequestered focus, usually within the kidney or prostate, shortly after completion of therapy. In reinfection, the course of therapy has successfully eradicated the infection and there is no sequestered focus, but organisms are reintroduced from the fecal reservoir. At least 90 percent of all recurrences are from reinfection.
Some women are subject to recurrent urinary tract infection.
Antimicrobial prophylaxis for as long as five years is effective in preventing recurrence of infection in these patients. The incidence of bacteriuria in pregnant women is four to 10 percent, at least double that for similarly aged nonpregnant women. Bacteriuria during pregnancy appears to be approximately twice as common in women with a history of childhood urinary tract infection as in women without such a history. Premature births and perinatal mortality may increase in pregnancies complicated by urinary tract infection. Although about 30 percent will have definite abnormalities on intravenous pyelogram that suggest chronic pyelonephritis, bacteriuria is not the cause of these long-term sequelae.