Severe gastroenteritis caused by Vibrio cholerae serogroup O24 in an immunocompromised patient: A case report.

Non-O1 and non-O139 Vibrio cholerae (NOVC) strains rarely harbor the cholera toxin gene and are typically associated with mild, self-limiting gastroenteritis. However, an increasing number of reports in recent years have described severe gastroenteritis or extraintestinal infections with fatal outcomes, particularly in immunocompromised individuals, such as those with underlying conditions including cirrhosis. Here, we describe a case of severe gastroenteritis caused by V. cholerae serogroup O24, following the consumption of seafood during prolong prednisolone treatment for systemic lupus erythematosus. Stool culture upon admission yielded yellow colonies on thiosulfate-citrate-bile salt-sucrose agar, and Gram staining of the colonies revealed Gram-negative, curved, comma-shaped rods, suggestive of Vibrio species. Although matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) yielded low-confidence identifications, suggesting either Vibrio mimicus or Vibrio albensis, the isolate was ultimately identified as NOVC based on its biochemical characteristics and salt tolerance. Subsequent genetic analysis confirmed the isolate as V. cholerae serogroup O24, a strain not included in the MALDI-TOF MS identification database. This case underscores the diagnostic value of conventional methods, such as biochemical profiling, in identifying V. cholerae strains not detectable by current mass spectrometry-based systems.