Serum as an environment to live or not to live for Gram-negative bacteria: relationship between lysozyme and complement system in killing Salmonella O48 strain

The bactericidal effect of serum plays a key role in humoral defense against microbial pathogens. Lysozyme - cooperates with the complement system in the bactericidal action of serum. Serotype O48 Salmonella belongs to clinically important bacteria causing diarrhoea in infants and children. Our present results demonstrated that the most efficient killing of Salmonella O48 occurred when all components of normal bovine serum (NBS) cooperated with each other. It is very interesting that elimination of lysozyme from NBS by using bentonite significantly decreased the bactericidal activity of NBS against Salmonella O48 strain. The results of X-ray diffractometric studies suggested that apart from lysozyme, other components of serum were adsorbed on the bentonite particles.