ANTIBACTERIAL ACTIVITY OF BILE-SALTS AGAINST COMMON BILIARY PATHOGENS- EFFECTS OF HYDROPHOBICITY OF THE MOLECULE AND IN THE PRESENCE OF PHOSPHOLIPIDS

In vitro studies have demonstrated that bile salts have cytotoxic and bacteriostatic properties. The cytotoxic effect of bile salts is reduc ed when lecithin is added. The effect of lecithin on the bacteriostati c property of bile salts is not known. In this report, we test the hyp otheses that (1) the bacteriostatic activity of bile salts is a functi on of the hydrophobicity of the molecules, and (2) lecithin, by engagi ng the hydrophobic component of bile salts, attenuates the bacteriosta tic property of these molecules. Two common biliary pathogens, Escheri chia coli and Enterococcus fecalis, were tested in this experiment The results demonstrated that hydrophobic bile salts (sodium taurodeoxych olate, sodium deoxycholate) have more significant inhibition on the gr owth of bacteria when compared with the hydrophilic bile salts (sodium taurocholate, sodium chenodeoxycholate, and sodium tauroursodeoxychol ate). When lecithin is added, creating a mixed micellar solution and m imicking the in vivo conditions, the antibacterial activities of even the more potent bacteriostatic bile salts are significantly reduced. T he finding that lecithin significantly attenuates the bacteriostatic p roperty of even the hydrophobic bile salts raises questions about the clinical significance of such bacteriostatic effect in vivo; as bile s alts in the bile exist in mixed micellar solution.