Two Cases of Enterobacter hormaechei Infection Misidentified as Cedecea davisae Infection

Enterobacteriaceae is a family of gram-negative, rod-shaped bacteria that consists of various species. Among these, members of the genus Cedecea has been reported as relatively rare causative pathogens of human infections. Commercially available automated identification systems that use biochemical reactions are known to accurately identify Enterobacteriaceae species. However, the accurate identification of some organisms with diverse biochemical profiles by these automated identification systems may be problematic. In this study, we report two cases of isolate misidentification, from patients with acute cholecystitis and deep vein thrombosis, as Cedecea davisae with VITEK II system. Both the isolates were correctly identified as Enterobacter hormaechei using gyrB gene sequence analysis. We also performed 16S rRNA sequence analyses and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analyses; however, indeterminate results were obtained from both the assays. Therefore, the sequence analysis of alternative genes, like gyrB, might be useful for accurate identification of species that belong to the family of Enterobacteriaceae.

A Case of Cedecea davisae Peritonitis in a Liver Cirrhosis Patient / 감염

Cedecea davisae is a motile, Gram-negative rod in the family Enterobacteriaceae which is positive for lipase, DNase and catalase, and negative for gelatinase and oxidase. This bacterium is rarely isolated in the clinical specimens. We isolated C. davisae from the ascitic fluid of a 49-year old male patient with liver cirrhosis who was diagnosed as acute bacterial peritonitis. Bacterial identification was performed by API 20E and VITEK. Antimicrobial susceptibility test showed that the isolate was susceptible to cefotaxime, piperacillin, and imipenem. Peritonitis of this patient was improved by imipenem therapy. This is the first reported case of peritonitis caused by this organism.