An electron microscopic study of pathogenesis of urinary tract infection caused by Pseudomonas aeruginosa P 9 in mice.

Scanning and transmission electron microscopic examination of the kidney and bladder of mice infected transurethrally with Pseudomonas aeruginosa P 9 revealed that the pyelonephritis is established through two routes, after the organisms reach the pelvis of the kidney via the bladder and ureter. In one route, which appeared to be predominant, the inoculated bacteria invaded the renal parenchyma through exfoliation of the calyceal epithelial cells with subsequent destruction of the basement membrane. Alternatively, the inoculated bacteria retrograded in the collecting tubules and urineferous tubules and propagated in the lumina followed by invasion of the renal parenchyma. In the bladder, the inoculated bacteria increased in number then disappeared within 48 h after exhibiting morphological aberrations such as elongation, bulge and spheroplast formation.