CAUGHT BY CONFUSA: A RARE CASE OF WEISELLA CONFUSA IN A LIVER TRANSPLANT PATIENT

Abstract

TOPIC: Critical Care TYPE: Medical Student/Resident Case Reports INTRODUCTION: Weisella confusa is a gram-positive bacteria typically found in gut flora. It is a rare cause of bacteremia in immunocompromised patients, especially those with malignancy. When grown in blood culture isolates, it serves as a harbinger of polymicrobial infection. It is inherently vancomycin resistant and treatment is based on susceptibility panel. In this case, we demonstrate W. confusa bacteremia in the setting of broad-spectrum antibiotic prophylaxis but no immunosuppressive therapy. CASE PRESENTATION: A 57-year-old woman with ulcerative colitis and autoimmune hepatitis and primary sclerosing cholangitis (PSC) overlap requiring liver transplant complicated by recurrent PSC was admitted for odynophagia due to a tongue lesion. She developed progressive synthetic liver dysfunction resulting in altered mental status, oliguric renal failure, and Klebsiella bacteremia with concurrent C. difficile colitis. Triple immunosuppressive therapy was halted and linezolid, aztreonam and oral vancomycin were initiated. Though she completed an antibiotic course with rapid clearance of bacteremia, prophylactic meropenem, micafungin, and oral vancomycin were administered and weekly surveillance cultures were drawn in anticipation of repeat transplant.One month later, four of four blood cultures grew W. confusa, followed by Lactobacillus rhamnosus, Enterococcus faecalis, and Candida krusei soon thereafter. Antimicrobials were escalated to amphotericin B, daptomycin, aztreonam, linezolid, and metronidazole, though she developed shock requiring multiple vasopressors. Computed tomography was obtained for source identification and demonstrated a right upper lobe pulmonary abscess and multiple hepatic abscesses. Upon discussions with the patient's family, care was withdrawn and she died soon after. DISCUSSION: W. confusa is a rare isolate from blood cultures and is generally associated with polymicrobial infections. Previous studies have shown that the majority of cases occur in the setting of malignancy, though there has been one other documented case in a liver transplant patient. In addition, a study conducted in pediatric liver transplant patients demonstrated Weisella isolates in stool samples, reflecting increased gut colonization with this organism. It is a naturally vancomycin resistant organism and misidentification as Lactobacillus by traditional speciation methods often results in inappropriate therapy. Here we demonstrate a case of Weisella bacteremia likely secondary to gut translocation. Given its natural vancomycin resistance, it is likely that prophylactic oral vancomycin for C. difficile resulted in W. confusa overgrowth and facilitated her decompensation via pre-existing defects to the gut mucosal barrier from ulcerative colitis. CONCLUSIONS: W. confusa should be considered an opportunistic bacteria warranting infectious disease specialist consultation to assist in management. REFERENCE #1: 1. Kamboj, K., Vasquez, A., & Balada-Llasat, J. M. (2015). Identification and significance of Weissella species infections. Frontiers in microbiology, 6, 1204. https://doi.org/10.3389/fmicb.2015.012042. Kumar, A., Augustine, D., Sudhindran, S., et. al. (2011). Weisella confusa: a rare cause of vancomycin-resistant Gram-positive bacteremia. Journal of Medical Microbiology, 60(10), 1538-41.3. Spiegelhauer, M. R., Yusibova, M., Rasmussen, I., Fuglsang, K. A., Thomsen, K., & Andersen, L. P. (2020). A case report of polymicrobial bacteremia with Weissella confusa and comparison of previous treatment for successful recovery with a review of the literature. Access microbiology, 2(5), acmi000119. https://doi.org/10.1099/acmi.0.0001194. Green, M., Barbadora, K., & Michaels, M. (1991). Recovery of vancomycin-resistant gram-positive cocci from pediatric liver transplant recipients. Journal of clinical microbiology, 29(11), 2503–2506. https://doi.org/10.1128/JCM.29.11.2503-2506.19915. Salimnia, H., Alangaden, G. J., Bharadwaj, R., Painter, T. M., Chandrasekar, P. H., & Fairfax, M. R. (2011). Weissella confusa: an unexpected cause of vancomycin-resistant gram-positive bacteremia in immunocompromised hosts. Transplant infectious disease : an official journal of the Transplantation Society, 13(3), 294–298. https://doi.org/10.1111/j.1399-3062.2010.00586.x6. Fairfax, M. R., Lephart, P. R., & Salimnia, H. (2014). Weissella confusa: problems with identification of an opportunistic pathogen that has been found in fermented foods and proposed as a probiotic. Frontiers in microbiology, 5, 254. https://doi.org/10.3389/fmicb.2014.00254 DISCLOSURES: No relevant relationships by Samuel Chung, source=Web Response No relevant relationships by Ashwin Kelkar, source=Web Response No relevant relationships by Joseph Mailman, source=Web Response