Sequential study of bacterial clearance in experimental cystitis.

Clearance of Escherichia coli in experimental cystitis was studied in the diuresing mouse model. Urine was collected daily; sediment was isolated by cytocentrifugation and either stained or treated with fluorescent antibodies directed against mouse immunoglobulins. During the initial phase of the infection the bacteria were either free and dispersed or adhering to epithelial cells but not generally to polymorphonuclear cells (PMNs). Subsequently, the bacteria adhered to each other, to epithelial cells and to PMNs, were phagocytosed by the latter and showed strong fluorescence. It is postulated that the appearance of opsonising and agglutinating antibodies in conjunction with activity of the PMNs is involved in bacterial clearance.