RoleofAdherence inPathogenesis ofEnterococcus faecalis Urinary TractInfection andEndocarditis

Enterococcusfaecalis strains isolated fromurinary tract infections (UTIs) andendocarditis wereanalyzed for their ability toadhere tourinary tract epithelial cells (ECs)andGirardi heart(GH)andhumanembryonic kidney (HEK)cell cultures. UTIisolates adhered tourinary tract ECsmore efficiently thantothecultured cells, atthesame timeshowing theleast affinity forGH cells. Incontrast, endocarditis isolates adhered toGH cell cultures more readily thantourinary tractECs.Moreover, although strains isolated fromendocarditis adhered toGH cells more efficiently thanthose derived fromUTI,thelatter strains adhered tourinary tract cells better thantheformer. Studies oftheability ofGH andIEK cells tointernalize E.faecalis showedthat forUTIisolates, 9to74%ofadhered bacteria were internalized, while forendocarditis isolates, thepercentage varied from76to82%.Allstrains were abletoassociate withhumanneutrophils; endocarditis strains, however, associated less efficiently thanUTIisolates. Growthinserum raised theadherence ofalltested strains byatleast 1.5- to3-fold, withthegreatest increase being observed inUTIstrain adherence toGH cells (8-fold). Incontrast, theassociation ofserum-growncells withpolymorphonuclear leukocytes was reduced bytwo-to fivefold. Inboth cases,theobserved serum-dependent alterations werecancelled byafewsubcultures in' brain heart infusion broth. Theseresults indicate thatadhesive properties areimportant virulence'factors inthe pathogenesis ofUTIandendocarditis andalsosuggest thatUTIstrains showing thehighest invasion and adhesive potential invade thekidneys, causebacteremia, and,after having expressed theserum-dependent surface modification, colonize theheart.