The role of periurethral colonization in the aetiology of recurrent urinary infection in women.

Periurethral bacterial colonization was studied in two groups of women by taking samples with a polystyrene sponge. Just over half (56 per cent) of 81 sexually-active women attending a family planning clinic were not colonized in the periurethral area; subjects who were colonized usually showed large numbers of a single bacterial species. On the other hand, all 38 patients who were attending a clinic because of recurrent urinary infections were colonized in the periurethral area; most of these yielded a heavy growth, and more than one bacterial species was usually isolated. Gram-positive cocci predominated as the colonizing flora in both groups, a finding which is in marked contrast to the predominant aetiological agents in urinary infections, namely Gram-negative bacilli. We therefore conclude that colonization of the periurethral area is not the decisive event in the initiation of a urinary infection.