EXPERIMENTAL STUDIES ON URINARY TRACT INFECTION

Bladder and Kidney Lodgements in Mice by Strains of Staphylococcus epidermidis

Abstract

Eight strains of Staphylococcus epidermidis were isolated from clinical specimens and were subjected to the tests for encapsulation, slime-production, mouse-virulence, capsular-typing and adherence to the plastic surface, the renal cells and the bladder epithelial cells.
With the intraperitoneal injection of these strains into mice, three encapsulated strains were observed in mouse-virulent, while two slime-producing and three unencapsulated strains were mouse-avirulent. In ultra-thin sections of mouse-virulent strains, capsules were demonstrated by electron microscopy, however no capsule was seen around the walls of mouse-avirulent strains. On the other hand, slime-producing strains were shown to have higher adherence rate to plastic surface, compared to encapsulated strains. The direct adherence rate to the bladder epithelial cells was greater in the encapsulated strains than the slime-producing strains, although there was no difference to the renal cells. Also, cell suspension containg 10⁷ colony forming units of these strains were injected intravenously or intravesically into mice. Of these encapsulated strains showed kidney and bladder lodgements with in 28 and 21 days after intravesical injection, respectively, although slime-producing and unencapsulated strains could only be obtained for 7 days in the kidney and 3 days in the bladder. However, there was no difference in the internal organs lodgements of the strains after intravenous injection into mice.
These experimental results suggested that the encapsulation of the strains would be an important factor for bladder lodgement, however, significant effects were not observed with the slime-producing and unencapsulated strains.