1Department of Internal Medicine, Fukuwatari Municipal Hospital, 1000 Fukuwatari, Takebe-cho, Kitaku, Okayama, 709-3111 Japan
2Department of Gastroenterology and Hepatology, Kurashiki Central Hospital, 1-1-1 Miwa, Kurashiki, Okayama, 710-8602 Japan
3Department of Internal Medicine, Nippon Kokan Fukuyama Hospital, 1840 Tsunoshita, Daimon-cho, Fukuyama, 721-0927 Japan
4Department of Surgery, Nippon Kokan Fukuyama Hospital, 1840 Tsunoshita, Daimon-cho, Fukuyama, 721-0927 Japan
5Department of Bacteriology, Okayama University Graduate School of Medicine Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama, 700-8558 Japan
6Center for Innovative Clinical Medicine, Okayama University Hospital, 2-5-1 Shikata-cho, Okayama, 700-8558 Japan
7Department of Medicine and Medical Science, Okayama University Graduate School of Medicine Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama, 700-8558 Japan