Citrobacter freudii septicemia in a newborn stranded cuvier´s beaked whale (Ziphius cavirostris)

Abstract

Citrobacter freundii has infrequently been identified in cetaceans, and although not reported as a cause of death, its likely importance in relation to dolphin health has been hypothesized. Here we report a case of a stranded neonatal beaked whale showing a bacteremia-septicemia caused by a systemic infection of Citrobacter freundii. Subcutaneous hemorrhage of the musculature of the dorsal area was observed without corresponding externa! skin marks. Lungs and pulmonary lymph nades were edematous. The stomach was empty and meconium­like material was still present in the colorectal lumen. Microscopically, lungs showed diffuse marked congestion and alveolar proteinaceous edema. Diffuse subepithelial edema in the bronchial mucosa, epithelial cell debris, alveolar macrophages and squamous epithelial cells within the bronchial and bronchioalveolar spaces with numerous bacteria. Basophilic microorganisms with hematoxilin and eosin technique showed immunoreaction by using a serum anti-C. freundii. Microbiologic identification was done by morphologic and biochemical characterization of brain, lung, liver and kidney isolates. The isolates were identified definitively by molecular methods. The almost complete 165 rRNA gene of each isolate was sequenced. The 165 rRNA gene analyses revealed that the isolates were genotypically identical, and were 99.9% similar to the type strain of Citrobacter freundii DSM 30039T (NR_028894).