[Prophylactic oral antibiotics in urethral instrumentation].

Between July 1990 and December 1992, the incidence of infection after 1,249 urethral manipulations on patients, who had no urinary infection before the manipulation, was studied. Infections developed in 21 patients (1.7%). The prophylactic 3-day antimicrobial medication reduced the development of infection to 5/790 (0.6%), in contrast to 16/459 (3.5%) among patients who did not take the prophylactic antimicrobial (P = 0.0004). Of the procedures studied, urethral dilation with sounds and retrograde urethrography were not so dangerous as cystoscopic examination. After cystoscopic examinations, 5 (1.4%) out of 347 males with prophylactic antimicrobial developed infection, although none of the prophylacted 135 females developed infection. Elderly persons had greater risk of developing the infection. The most disastrous bacteria was P. aeruginosa.