ABSTRACT
It seems that rapid destruction of gram negative bacteria by antibiotics contributes to the clinical deterioration of some patients with gram negative infections. Antibiotics increase the concentration of lipopolysaccharide [LPS] in blood and cerebrospinal fluids. Released LPS can activate blood cells to produce tumor necrosis factor-alpha [TNF-alpha] and other cytokines. TNF-[alpha] appears to be a major mediator in development of fever, hypotension, multi-organ failure and death. In this research, standard Salmonella typhi Ty[2] -5536, a pathogenic Salmonella and standard Escherichia coli K12,QD5003 for comparing, were incubated in the presence of chloramphenicol, ampicillin and co-trimoxazole at concentrations that killed >99.9% of organisms as determined by quantitative culture techniques. The results obtained showed that chloramphenicol produced lower LPS levels and lower TNF-[alpha] levels from whole blood cells when compared with those of ampicillin and co-trimoxazole. Therefore chloramphenicol is the preferred antibiotic against S. typhi because it decreases the induced-pathological effect of TNF-[alpha] in gram negative infections