We have reported a case of E sakazakii primary bacteremia in an elderly patient in whom evaluation failed to reveal a source of infection. This patient had an uneventful recovery after intravenous administration of a third-generation cephalosporin for 7 days followed by 1 week of oral ciprofloxacin. This excellent response supports the previous suggestion that agents more active against gram-negative bacilli should be considered, despite apparent susceptibility to less active agents. Since this case attests to the pathogenicity of this organism in adults, isolation of the organism from clinical specimens should not be dismissed as contamination.