1. Gastroentero-Hepatology Division, Department of Internal Medicine, Faculty of Medicine–Dr. Soetomo Teaching Hospital, Universitas Airlangga, Surabaya 60286, Indonesia.
2. Helicobacter pylori and Microbiota Study Group, Institute of Tropical Disease, Universitas Airlangga, Surabaya 60115, Indonesia.
3. Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Yufu 879-5593, Japan.