Crohn disease and mycobacterial infection in children: an intriguing relationship.

The relation between Crohn disease (CD) and mycobacterial infection is complex and intriguing. The 2 conditions share common immunopathogenic features, and the hypothesis that Mycobacterium avium subspecies paratuberculosis may cause CD is still under debate. Moreover, differential diagnosis between CD and intestinal tuberculosis (TB) may be challenging, especially in the growing proportion of children immigrating from countries with a high prevalence of TB. Thus, in Western countries, paediatricians who are involved in the diagnosis and management of children with CD are expected to face intestinal TB more frequently than in the past and should always consider the differential diagnosis between these 2 conditions. In addition, the use of biological agents in the treatment of CD, which may reactivate latent TB, requires the development of targeted diagnostic algorithms. Children with CD who are candidates for treatment with antitumour necrosis factor-alpha agents should be screened for latent or active TB and closely followed over time, also considering possible failure of antitubercular prophylaxis and the frequent uncharacteristic presentation of TB in children receiving antitumour necrosis factor-alpha agents. In the present review, the most recent literature findings on these topics are reported, focusing particularly on the paediatric age group.