Ulcerative colitis after Salmonella infection

An 11-year-old boy was referred to our hospital with intestinal salmonellosis (group O4), presenting with severe abdominal pain, diarrhea, hematochezia, and high fever. The symptoms promptly resolved with tosufloxacin, and the stool cultures became negative continuously. However, hematochezia persisted, and the fecal calprotectin (FCP) level was 2250 mg/kg. One month after the onset, total colonoscopy (TCS) revealed mucosal redness and edema with small aphthae in the sigmoid colon (Figure 1A), indicating pathologically nonspecific inflammation (Figure 1B). Conversely, no lesions were observed in the rectum (Figure 1C). Subsequently, the grossly bloody stool disappeared completely within 2 weeks after the first TCS; however, the fecal occult blood test (FOBT) remained positive, the FCP level remained high (2930 mg/kg) despite the absence of gastrointestinal symptoms, and only tenesmus appeared 1 year after the first TCS. A second TCS for the tenesmus revealed diffuse redness, erosions, and granular mucosa with a loss of vascular permeability from the sigmoid colon to the rectum (Figure 2A,B). Pathological examination revealed inflammatory cell infiltration, basal plasmacytosis, decreased goblet cells, and cryptitis, consistent with ulcerative colitis (UC) (Figure 2C). Based on these findings, oral intake of 5-aminosalicylate and topical steroids was started, which resolved the tenesmus immediately and normalized the FOBT and FCP levels promptly.

Salmonella infection can trigger UC development by causing permanent changes in the intestinal microbiota, disrupting the epithelial barrier, and altering the intestinal immune response.^{1, 2} Salmonella infection is associated with an 8–10-fold increase in the risk of UC development within the following year.³ In this case, the lesions skipped the rectum in the first TCS, which is a characteristic finding of Salmonella enteritis, in contrast to the lesions that continued from the rectum in UC. Subsequently, no gastrointestinal symptoms were observed; however, tenesmus was observed 1 year later, and UC was diagnosed endoscopically and pathologically in a second TCS. Although the onset time of UC is difficult to confirm, UC certainly developed after Salmonella enteritis. Therefore, when persistent intestinal symptoms occur after an episode of intestinal salmonellosis, the possibility of UC should always be considered.

Toshihiko Kakiuchi: Conceptualization; investigation; writing – original draft; methodology; validation; supervision. Masato Yoshiura: Investigation; writing – review and editing.

The authors did not receive support from any organization for the submitted work.

The authors declare no conflict of interest.

Ethics approval statement: We confirm that written informed consent was obtained from the patient's parents for publication of the clinical images and accompanying text. The patient's parents was informed that the images and text would be published in a journal accessible to the public, and anonymity was ensured by omitting identifiable information.

Patient consent statement: Written informed consent was obtained from the patient's parents. Since the patient was 11 years old, we received a consent form from her parents. The patient's parents gave informed consent, and patient anonymity was preserved.

Clinical trial registration: None.