Weissella confusa bacteremia in a liver transplant patient with hepatic artery thrombosis

A 54-year-old man with a history of nonalcoholic steatohepatitis and hepatocellular carcinoma presented 2 months after an orthotopic liver transplant with fever and abdominal pain. Two weeks earlier, he had an hepatic artery thrombosis and a biliary stricture, for which an hepatic artery stent and a biliary stent were placed. Laboratory workup was significant for leukocyte count of 7800/mcL with 92% segmented neutrophils, hemoglobin 9.4 g/dL, alanine aminotransferase 98 U/L, aspartate aminotransferase 72 U/L, alkaline phosphatase 358 U/L, albumin 2.8 mg/dL, and total bilirubin 1.6 mg/dL. A computed tomography scan of the abdomen and pelvis revealed multiple small fluid collections in the liver consistent with bilomas, and an hepatic angiogram showed complete occlusion of the common hepatic artery. Two sets of blood cultures were positive for an organism initially identified by MicroScan(®) analysis as an α-hemolytic Streptococcus species that was resistant to vancomycin. Further testing confirmed the organism as Weissella confusa 2 days later. W. confusa is a gram-positive coccobacillus that may be misidentified as a Lactobacillus when cultured. It is commonly found in sewage, carrots, sugar cane, fermented foods, and intestinal flora. Although only 4 cases of clinical infection with W. confusa have been described previously, W. confusa has been isolated from the stool of liver transplant patients, and may be an underreported cause of infection owing to improper identification. As it can cause clinical infection in these immunosuppressed hosts, identification of this organism is paramount because it is vancomycin resistant, and incorrect identification could lead to improper antimicrobial selection and ultimately worsened patient morbidity or mortality.