Bacteremic cholangitis due to Raoultella planticola complicating intrahepatic bile duct stricture 5 years post-laparoscopic cholecystectomy: a case report.

BACKGROUND Raoultella Planticola is a facultative anaerobic, gram-negative, water- and soil-dwelling rod bacterium rarely reported as a cause of human disease. However, the number of reported R. planticola infections is growing, without a concomitant increase in research on the microbe or its pathogenesis. Previous genomic studies demonstrating genetic similarities between R. planticola and Klebsiella pneumoniae suggest that capsule biosynthesis, mucoid phenotype, biofilm production, and lipopolysaccharide (endotoxin) synthesis may all be potential virulence factors of R. planticola. We present a unique case of R. planticola infection of the biliary tract 5 years after biliary surgery in a patient with no previously documented risk factors. We also use in silico techniques to predict virulence factors of R. planticola. CASE PRESENTATION This case report is the first to discuss a R. planticola infection in the biliary tract of late onset post-surgery (5 years) in a Caucasian patient with no previously documented risk factors. CONCLUSIONS An in-depth search of the current literature did not yield other similar cases of R. planticola infections. Moreover, to the best of our knowledge, our case is the first case of R. planticola isolated from post-endoscopic retrograde cholangiopancreatography (ERCP) as part of biliary sepsis not associated with gastroenteritis. The late onset of the infection in our patient and the results of the in silico analysis suggest that R. planticola may have survived exposure to the host immune system through the creation of an intracellular biofilm or in a non-culturable but viable state (NCBV) for the 5-year period. The in silico analysis also suggests that biofilms, enterobactin, and mucoid phenotype may play a role in the pathogenesis of R. planticola. However, further research is needed to illuminate the significance of pili, capsule biosynthesis, and lipopolysaccharide (LPS) in the virulence of R. planticola. Lastly, as our patient did not have any risk factors previously associated with R. planticola, we suggest that biliary tract stricture, cholecystitis, and prior surgery may be possible novel risk factors.