Adherence of bacteria to heart valves in vitro.

Abstract

A B S T R A C T The abilities of 14 strains of aerobic gram-positive cocci and gram-negative bacilli to adhere in vitro to human or canine aortic valve leaflets were compared. 2-mm sections of excised valve leaflets were obtained by punch biopsy and were incubated under standardized conditions in suspensions of bacteria. Valve sections were subsequently waslhed and homiogeniized, and quantitative techniques were used to determine the proportions of bacteria from the initial suspensions that had adhered to the valve sections. Comparable results were obtained when these adherence ratios were determined by two independent methods based either on measurements of bacterial viability or of radioactivity in 5"Cr-labeled bacteria. For each bacterial strain, the adherence ratio was constant over a wide range of concentrations of bacteria in the incubation mediuiml. Strains of enterococci, viridans streptococci, coagulase-positive and coagulase-negative staphylococci and Pscudoim oinas aeruginosa (adherence ratios 0.003-0.017) were found to adhere more readily to valve sections than strains of Escherichia coli and Klbsiella pfeum;oniiac (adherence ratios 0.00002-0.00004). The organisms that most frequently cause bacterial endocarditis Nwere found to adhere best to heart valves in vitro, suggesting that the ability to adhere to valvular endothelium may be an important or essential characteristic of bacteria that cause endocarditis in man.

Fibrinogen acts as a bridging molecule in the adherence of Staphylococcus aureus to cultured human endothelial cells.

“…Previous in vitro studies have shown that S. aureus is more adherent than enteric gram-negative bacilli to the native endocardial surface (4,5,34). However, these studies are largely accomplished in systems where the assays were performed either in the presence of serum or devoid of plasma factors altogether.…”

“…In particular, S. aureus accounts for one-quarter to one-third ofthe episodes ofbacteremia associated with intravascular devices (3). One intriguing aspect of the pathogenesis of S. aureus bacteremic infections in a human host is the unique ability of the organism to adhere to and colonize the endothe-Receivedfor publication 4 June 1990 and in revisedform 25 January 1991. lium (4) during transient bacteremia (5,6). In the case ofcatheter-related bacteremia, the prevailing view is that bacterial colonization starts at the skin-catheter junction, advances down the fibrin-coated external surface of the device (7) and ultimately seeds the bloodstream (2).…”

Bacterial adherence in the pathogenesis of endocarditis. Interaction of bacterial dextran, platelets, and fibrin.

“…This difference is statistically significant (X2 = 4.78, 0.02 < P < 0.05). (32). These two studies suggest that bacterial adherence in vitro may correlate with the relative predilection of certain organisms to produce endocarditis in vivo and also with the relative frequency of the disease in man.…”

Periodontitis, Bacteremia and Infective Endocarditis: A Review Study

“…Adherence rates upon damaged aortic valve leaflets were measured from several species and it was found that Enterococcus spp. and viridans streptococci showed the highest rates of adherence than Escherichia coli (84). The ubiquitous presence of fibronectin on damaged tissue enables a surface binding protein, Fim A, to aid in colonization.…”