DISPLACEMENT OF STREPTOCOCCUS-ZOOEPIDEMICUS FROM EQUINE UTERINE EPITHELIUM BY N-ACETYL-D-GALACTOSAMINE IN-VITRO

The capability of bacteria to adhere to host cells, such as the uterin e epithelium, is an essential step for the survival of the infectious agent and subsequent pathogenesis. Some bacteria, but not all, attach to specific sugars on the surface of mucosal cells. Lectins on the sur face of the bacteria mediate this type of binding to mucosal sugars by specific ''lock and key'' interactions. Streptococcus zooepidemicus i s one of the bacteria commonly associated with endometritis in suscept ible mares. The purpose of this study was to determine: 1) which sugar (s) competitively inhibit the attachment of S. zooepidemicus to the en dometrium in vitro; 2) whether the sugar attaches to S. zooepidemicus or to the epithelium; 3) if the sugar could displace S. zooepidemicus from the mare's mucosa in vitro. Fresh endometrial biopsies from diest rus uteri, were incubated with S. zooepidemicus (0.5 ml of 10(9) cells /ml suspension, O.D.= 0.9 at 640 nm) in the presence of no sugar (cont rol), N-acetyl-D-galactosamine (D-galNAc), D-(+)-mannose, a-D-(+)-gluc ose or N-acetyl-D-glucosamine (D-gluNAc)(sugar concentration=25 mg/ml) . Bacterial colonization was significantly reduced by D-galNAc and D-( +)-mannose when compared to controls (p<.05). However, the other sugar s were ineffective in decreasing the degree of attachment (P<.05). The number of bacteria attached to each colonized cell did not differ sig nificantly from control for any treatment. In the second experiment, i ncubation of D-galNAc with S. zooepidemicus prior to its contact with tissue, significantly inhibited bacterial colonization of the epitheli um. No significant decrease in bacterial attachment was observed when this sugar was incubated with the endometrium prior to the introductio n of the bacteria. These results indicate that this sugar acts upon th e bacteria and not the endometrium to prevent binding. In the third st udy, uterine tissue was incubated with S. zooepidemicus for 1 h to est ablish attachment of the bacteria. Then D-galNAc was added to the cult ure. This resulted in a significant displacement of the bacteria from the tissue.