A 10-month-old boy was brought to our hospital with fever, watery stool, and poor vitality. He developed fever from the 1st day, water stool (15-20 times a day) from the 2nd day, and poor vitality from the 7th day of illness. Vomiting occurred twice only on the 2nd day. He was hospitalized on the 7th day due to persistent symptoms and poor oral intake and vitality. He was previously healthy, with no recent history of travel, contact with sick individuals, or exposure to pets. His body temperature was 40.8 C; pulse, 184 bpm (normal); blood pressure, 121/66 mmHg; and respiratory rate, 36 breathes/min with an oxygen saturation of 99% on room air. On physical examination, he was nonresponsive and had cervical lymphadenopathy, increased bowel sounds, and peripheral cold sensation. No other lymph node swelling, rash, or edema was observed (Figure 1). Initial laboratory results revealed elevated inflammatory markers (white blood cell (WBC) count, 15,750/muL; C-reactive protein (CRP), 16.83 mg/dL; and procalcitonin, 8.4 ng/mL) and hyponatremia (130 mmol/L). Cervical ultrasonography revealed mild reactive lymphadenopathy (Figure 2). Abdominal ultrasonography (Figure 3) and computed tomography (CT) (Figure 4) revealed pitting-like wall thickness of the entire colon and an enlarged appendix.
Initially, estimating the pathogenic bacteria and infection route was difficult through interviews; therefore, a broad-spectrum antibiotic therapy was administered (ampicillin: ABPC, 200 mg/kg/day + ceftriaxone (CTRX), 100 mg/kg/day). On the same day, 2-3-min convulsions occurred with upturn of the eyeball and poor complexion. Convulsions were identified as systemic tonic, without left-right differences. Cranial CT revealed no abnormal findings such as cerebral edema or neoplastic lesions, and cerebrospinal fluid examination revealed normal leukocyte levels or hypoglycemia (cerebrospinal fluid (CSF): glucose level of 73 mg/dL as compared to simultaneous blood glucose level of 113 mg/dL, protein of 13 mg/dL, and cell count of 4 cells/muL with 58% cells being neutrophil).
On day 9 of illness, symmetrical pale erythema without blisters and bulges were observed on the patient's face and trunk. Follow-up laboratory results on the same day were as follows: WBC, 13290/muL and CRP, 23.3 mg/dL. The blood culture on the 7th day of the illness (hospitalization date) was reported to be positive for Gram-negative rod and was identified as Y. pseudotuberculosis. On the next day, the guardian was reinterviewed, revealing that they had been using spring water from nearby valleys for domestic purposes. The spring water was boiled and then used to melt the formula (artificial milk). Antibiotics were changed to meropenem (MEPM, 120 mg/kg/day), and intravenous immunoglobulin (IVIG, 500 mg/kg/day) was administered for hypogammaglobulinemia (443 mg/dL). On day 10 of illness, the fever subsided. On day 11, antibiotics were changed to ABPC (200 mg/kg/day) based on the antibiotic sensitivity to Y. pseudotuberculosis. Intravenous albumin (10 g/dose/day) was also administered because of body weight gain and edema associated with hypoalbuminemia. These treatments gradually improved his watery stool, rashes, and cervical lymphadenopathy. Oral intake became possible on day 12 of illness, antibiotics were continuously infused until day 18, and he was discharged on day 19. During the hospitalization, no symptoms of acute renal failure were suspected. Finally, Y. pseudotuberculosis was detected from the stool culture and loop-mediated isothermal amplification (LAMP), and Y. pseudotuberculosis-derived mitogen (YPM) antibody was also increased, resulting in the diagnosis of enteritis and bacteremia due to Y. pseudotuberculosis. After discharge, he presented desquamation of both hands on the 30th day of illness. He has been under follow-up care without coronary artery lesions.