Crohn's disease (CD) is a chronic relapsing-remitting systemic inflammatory disease, affecting any part of the gastrointestinal tract. Biological therapy with anti-tumor necrosis factor (TNF) alpha is the established treatment of choice for the management of moderate to severe Crohn's disease. However, its efficacy in an individual patient is the unpredictable and long-term outcome is still suboptimal. Identifying biomarkers which can predict treatment response is thus of utmost importance and can allow personalized management.||In inflammatory bowel disease (IBD), altered fecal microbiota signatures have been consistently reported. Moreover, overall bacterial diversity is consistently decreased during intestinal inflammation.||Fecal calprotectin (FC) is a calcium and zinc binding protein largely confined to the neutrophil granulocytes and macrophages and is a very sensitive marker for detection of inflammation in the gastrointestinal tract.||C reactive protein (CRP) is an acute phase reactant. CD Patients with elevated baseline CRP levels responded to infliximab treatment better and early normalisation of CRP correlated with sustained long-term response to infliximab therapy.||The investigators hypothesize that faecal microbial signatures in conjunction with faecal calprotectin and CRP may have a role in predicting response to biological therapy in CD patients.