Walsh & Hoyt: Gram-Negative Bacilli

Gram-negative bacilli produce a variety of severe systemic infections, most of which can be associated with neurologic and ophthalmologic manifestations. Because gram-negative bacilli are a major component of the abundant native microbial flora in humans, it may seem paradoxic that these organisms so often produce severe infectious disease. In most cases, the major factor seems to be microbial opportunism in the setting of significant depression of host defenses. In addition, as noted previously, gram-negative bacteria contain endotoxin, the lipopolysaccharide component of the cell wall. This material triggers many of the adverse systemic reactions and serious sequelae in patients with sepsis and gram-negative bacteremia. Unfortunately, many patients withgram-negative bacteremia who are not overtly septic develop significant neurologic disturbances before their bacteremia is discovered and adequately treated.