CURRENT PERSPECTIVES IN SALMONELLOSIS

Salmonellosis remains an important human and animal problem worldwide and, despite extensive research effort, many of the details of its pat hogenesis are not known. While there have been recent advances in some aspects of pathogenesis, other areas are not understood. The host ada ptation shown by several serotypes and the recent dramatic changes in the predominance of particular serotypes are examples. Molecular techn iques using in vit ro model systems ha-ve identified several genes inv olved in adhesion and invasion, though their function and even their r elevance to disease remain poorly defined. Similarly, several potentia l toxins have been identified and the genes cloned, although their sig nificance is far from clear. Some of the essential genes on the large virulence plasmids have been defined, and these are known to be necess ary for the establishment of systemic infection. Two of these genes ar e regulatory, but the function of the other genes is unknown. A genera l theme has been the identification of gene systems involved in regula tion of virulence. New vaccines, based on 'rational attenuation' are b eing designed, and these have also been used to carry heterologous ant igens; such vaccines are currently undergoing trials. The improved und erstanding of the pathogenesis of salmonellosis may also provide a mod el of wide applicability to a more general understanding of bacterial pathogenesis. New techniques, including the polymerase chain reaction, are being applied to diagnose salmonellosis.