D

66 kDa Gp CD11/18 Gp CD 48Gpb Uroplakinc

Adapted from Ofek and Doyle, 1994. aA. Target host cell express one receptor molecule that contain three attachment sites fro three different adhesins produced by three clones of bacteria; B. Two bacterial species express two distinct adhesins that bind the bacteria to the same receptor molecule on target host cell; C. The same bacterial clone produce a fimbrial structure comprised of two subunits, each bind the bacteria to distinct receptor on host target cell; D. The same adhesin bind the bacteria to similar attachment sites contained in different receptor molecules (isoreceptors) expressed by various host target cells. bBaorto et al., 1997; cWu et al., 1996. Gp, Glycoprotein.

Erythrocytes Erythrocytes Erythrocytes

Epithelial cell

Uroepithelial cell

Dra fimbriae AFA II F 1845 fimb

Lipoteichoic acid Fibronectin binding protein

P fimbriae, FsoG P fimbriae, FsoF/H

S. pyogenes S. aureus

E. coli, (pyelonephritis)

Erythrocytes Neutrophils Macrophages Uroepithelial cell

Type 1 fimbriae Type 1 fimbriae Type 1 fimbriae Type 1 fimbriae

E. coli, (mannose sensitive)

toire of its target tissues and perhaps also acquire antigenic variability that will enhance its ability to withstand the multifaceted defenses of the host (Ofek and Doyle, 1994b). This notion is exemplified by pyelonephritic isolates of E. coli which express either P fimbrial or type-1 fimbrial adhesin at any given time. Because transmission from one host to another is via the feacal-oral route, it was postulated that the pyelonephrito-genic isolates may need the type 1 fimbriae mainly to transiently colonize the upper respiratory tract. Such colonies might then provide a constant source of bacteria entering the stomach and thus increase the chances for the incoming bacteria to colonize the intestine (Bloch et al., 1992). Once in the urinary tract, the bacteria seem to need the P fimbrial adhesins to adhere to the urinary tissues (Roberts et al., 1994; Win-

berg et al., 1995). In fact, the diverse types of fimbrial adhesins carried by various enterobacte-ria may determine by virtue of their distinct receptor specificity which of the unique niches along the intestine are colonized (Edwards and Puente, 1998).

In those instances where multiple adhesins are expressed simultaneously on the same organism, each adhesin appears to complement the other functionally. For instance, the cell surface LTA and the M protein co-expressed on the surface of Streptococcus pyogenes have both been implicated in mediating bacterial binding to Hep-2 cells (Hasty et al., 1992; Courtney et al., 1997). Adhesion of S. pyogenes appears to involve a two-step process. The first step is mediated by the interaction of LTA with fibronectin molecules on the host cells (Hasty et al., 1992) and the second

Table 4. Selected bacterial clones expressing multiple adhesins.

Bacterial clone

Source of isolation

Adhesin

Characteristics

E. coli

Pyelonephritis

Type P

Fimbrial lectin

0 0

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