Study design
This was a retrospective case control study to assess the ultrasonic findings and clinical features in children with bacterial enteritis, including Ye infection.
Patients
This study was carried out as part of the "Technology development and examination of intestinal blood flow quantification in child abdominal ultrasonography" study at Juntendo University (approved by the institutional ethics committee, Faculty of Medicine, Juntendo University, Japan as No. 13-072). In this retrospective investigation, data for all patients aged between 3 to 18 years old at the time of treatment and who were eligible according to the inclusion criteria were obtained from the electronic medical records of pediatric outpatient and emergency room of the Department of Pediatrics, Faculty of Medicine, Juntendo University, Japan between 2014 and 2017. Detailed medical histories were obtained from the parents of all patients when ultrasonography was performed at the first visit. The inclusion criteria of this study were 1) suffering from fever and gastrointestinal symptoms such as abdominal pain, diarrhea, and vomiting; 2) detection of any pathogen from stool culture; and 3) performance of abdominal ultrasonography at the first visit. The exclusion criteria of this study were 1) previous abdominal surgery; 2) history of bacterial enteritis or other digestive diseases diagnosed by pediatricians; 3) chronic medical history of recurrent abdominal pain or diarrhea; 4) growth retardation on the growth curve; 5) administration of antibiotics or any other drugs at the first visit; or 6) cases with no clear ultrasonic images available for analysis.
Subject preparation
Patients were divided into two groups according to the results of stool cultures: a Ye group, in which Ye enteritis was detected; and a non-Ye group, in which enteritis was attributed to other pathogens such as Campylobacter jejuni, Salmonella, and Escherichia coli. Clinical features, inflammatory markers like WBC and C-reactive protein (CRP), and abdominal ultrasonic findings were compared between groups. Assessment of abdominal ultrasonography
Abdominal ultrasonography was performed in all children. All ultrasonic examinations were performed by two pediatricians (Jimbo K and Miyata E), with 14 and 8 years of experience in pediatric ultrasonic, respectively, using a HI VISION Preirus® system (Hitachi-Aloka Medical, Tokyo, Japan) and an 8- to 12-MHz high-frequency linear transducer (EUP-L54MA®; Hitachi-Aloka Medical). The ultrasonic findings were accepted when the interpretations of the two sonographers matched. Ultrasonic studies were performed when the patients were either not moving or sleeping, to minimize ultrasonic artifacts. Abdominal ultrasonic findings were assessed using the following three parameters (Fig. 1) and the results were recorded in a data sheet:
1) Measurement of maximum and minimum diameter in five randomly selected ileocecal lymph nodes (C-LNs) and calculation of mean major/minor axis ratio of the five C-LNs.
2) Measurement of wall thickness of the terminal ileum. The terminal ileum was defined as the ileum exiting within 5 cm from ileocecal valve on the oral side, and wall thickness of the ileum was defined as abnormal thickening for values >3.0 mm. Thickness was measured by placing a pointer between the mucosal surface and the serosa in the bowel loop [8].
3) Detection of the presence of a pericecal hyperechoic region. A pericecal hyperechoic lesion was defined as a cecal and terminal ileal extraluminal hyperechoic band thicker than 4.0 mm, which was defined from the bowel serosa to the edge of the hyperechoic band, and clearly distinguishable from the terminal ileum and thickened intestinal tract around the ileocecal region.
Statistical analysis
BellCurve for Excel software (Social Survey Research Information, Tokyo, Japan) was used to perform statistical analysis. Continuous variables are presented as mean value, standard deviation (SD) and range or median value, as appropriate. Categorical variables are expressed as counts (percentage). The chi-squared test was used for comparisons with more than five categorical variables. The nonparametric Mann-Whitney U test was used to compare data showing skewed distributions. Values of p < 0.05 were considered statistically significant for blood tests and abdominal ultrasonic findings between the Ye and non-Ye groups. Furthermore, receiver operating characteristic (ROC) analysis was performed for maximum diameter, mean long-short diameter ratio of C-LNs, and wall thickness of the terminal ileum, and significant differences between the respective areas under the curve (AUCs) were analyzed. The point closest to the point (0, 1) on the ROC curve was taken as the cut-off value, and sensitivity and specificity were calculated. The statistical methods of this study were reviewed by Nobuaki Matsunaga, MD, PhD, from the Antimicrobial Resistance Clinical Reference Center, National Center for Global Health and Medicine Hospital.