1. Department of Gastroenterology, Sapporo City General Hospital, 1-1, N-11, W-13, Sapporo 0608604, Japan
2. Department of Clinical Laboratory Testing, Sapporo City General Hospital, 1-1, N-11, W-13, Sapporo 0608604, Japan
3. Department of Microbiology, Faculty of Pharmaceutical Science, Tokushima Bunri University, Yamashiro-cho, Tokushima 7708514, Japan
4. Department of Infectious Diseases, Sapporo City General Hospital, 1-1, N-11, W-13, Sapporo 0608604, Japan