A previously undescribed gram-negative bacillus causing septicemia and meningitis

This report describes a case of septicemia and meningitis secondary to dog bites by two different dogs on two consecutive days. The case is noteworthy because of the unusual characteristics of the etiologic agent and the inability to place the etiologic agent into any currently defined genus or to identify it by the existing systems of classification. The organism is a small, thin, Gram-negative bacillus after 24 hours of incubation on blood agar; after prolonged incubation, it becomes filamentous. The organism is catalase- and oxidase-positive, hydrolyzes esculin, and forms acid in glucose, xylose, and maltose after 21 days' incubation. The organism does not manifest lysis on sheep blood agar, and does not grow on MacConkey, Salmonella-Shigella, Centrimide, nutrient, or Kligler iron agars. The tests for urea, nitrate reduction, and indol are negative. The unidentified Gram-negative bacillus showed susceptibility to all antimicrobials tested except gentamicin.