Identification of Kosakonia cowanii as a rare cause of acute cholecystitis:case report and review of the literature

BACKGROUND: Kosakonia cowanii, formerly known as Enterobacter cowanii, is a Gram-negative bacillus belonging to the order Enterobacterales. The species is usually recognized as a plant pathogen and has only anecdotally been encountered as a human pathogen. Here we describe the rare case of a K. cowanii infection presenting as an acute cholecystitis and provide a review of available literature. Evident difficulties in species identification by biochemical profiling suggests that potentially, K. cowanii might represent an underestimated human pathogen.

CASE PRESENTATION: A 61-year old immunocompromised man presented to the hospital with fever and pain in the upper right abdomen. Sonography revealed an inflamed gall bladder and several gall stones. A cholecystectomy proved diagnosis of an acute cholecystitis with a partial necrosis of the gall bladder. Surgical specimen grew pure cultures of Gram-negative rods unambiguously identified as K. cowanii by MALDI-TOF, 16S-rRNA analysis and whole genome sequencing.

CONCLUSIONS: Reporting cases of Kosakonia species can shed light on the prevalence and clinical importance of this rare cause of human infection. Our case is the first to describe an infection without prior traumatic inoculation of the pathogen from its usual habitat, a plant, to the patient. This raises the question of the route of infections as well as the pathogen's ability to colonize the human gut.