Unusual cause of appendiceal peritonitis: Comamonas kerstersii– A case report and literature review

Comamonas kerstersii is a non-fermentative Gram-negative bacterium recently described, and its role in serious human infections has been recognized since 2013. In this article, we report the case of a 53-year-old male admitted to the emergency room for acute abdominal pain in the right iliac fossa. Laboratory tests revealed an inflammatory syndrome with CRP at 399.02 mg/L and Procalcitonin at 5.21 ng/mL. An urgent abdominal computed tomography (CT) scan was realized, revealing appendiceal peritonitis. The patient underwent an appendectomy and fluid aspiration. The microbiological analysis of the peritoneal fluid led to the identification of Comamonas kerstersii by MALDI-TOF mass spectrometry. The recent discovery of C. kerstersii and the limits of classical phenotypic methods in its detection are probably leading to an underestimated prevalence. More recently, acquired resistance in this bacterium has been reported, requiring systematic susceptibility testing and the rapid adaptation of therapeutic strategies to improve patient outcomes.