Abstract
A previously healthy 23-year-old woman presented with acute diarrhea, abdominal pain, and bloody mucoid stool following raw beef consumption, with a fever of 37.8 °C. On admission, her vital signs were unremarkable. Blood tests revealed elevated C-reactive protein, hypokalemia, and hypoproteinemia. Abdominal ultrasonography clearly demonstrated severe right-sided colitis characterized by marked circumferential bowel-wall thickening (~2 cm), loss of normal wall stratification, and continuous involvement from the ascending to proximal transverse colon. To avoid unnecessary radiation exposure in this young, clinically stable patient, computed tomography (CT) was omitted. Stool culture yielded enterohemorrhagic Escherichia coli (EHEC) O157 and Campylobacter jejuni. While ultrasonography effectively delineated the severity and continuous extent of colitis, imaging alone could not differentiate between these pathogens or identify the concurrent coinfection. Furthermore, this dual infection presented a major therapeutic challenge: guidelines suggest macrolides for severe Campylobacter enteritis, but antimicrobials are strictly discouraged in EHEC O157 infection due to the risk of hemolytic uremic syndrome (HUS). Managed conservatively with fluid replacement and probiotics without antimicrobial therapy, she recovered uneventfully and was discharged on hospital day 9. This case highlights the primary diagnostic utility and safety of ultrasonography in evaluating acute right-sided colitis and underscores the importance of cautious supportive care when navigating conflicting therapeutic guidelines in rare gastrointestinal coinfections.