HP and gastroesophageal reflux disease: The abundance of Bifidobacterium in the CA/GU-Hp+ group was found to be significantly lower than the GERD-Hp− (p = 0.0181), NUD/GAS-Hp− (p = 0.0117), and NUD/GAS-Hp+ (p = 0.0229) groups (Figure 6C).