International guidelines concerning the management of patients
with sepsis, septic shock and multiple organ failure make no
reference to the nature of the infecting organism. Indeed, most
clinical signs of sepsis are nonspecific. In contrast, in vitro data
suggest that there are mechanistic differences between bacterial,
viral and fungal sepsis, and imply that pathogenetic differences
may exist between subclasses such as Gram-negative and Grampositive
bacteria. These differences are reflected in different
cytokine profiles and mortality rates associated with Gram-positive
and Gram-negative sepsis in humans. They also suggest that
putative anti-mediator therapies may act differently according to
the nature of an infecting organism. Data from some clinical trials
conducted in severe sepsis support this hypothesis. It is likely that
potential new therapies targeting, for example, Toll-like receptor
pathways will require knowledge of the infecting organism. The
advent of new technologies that accelerate the identification of
infectious agents and their antimicrobial sensitivities may allow
better tailored anti-mediator therapies and administration of antibiotics
with narrow spectra and known efficacy.