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