Risk of developing tuberculosis under anti-TNF treatment despite latent infection screening. 
In patients treated with TNF-antagonists, incident cases of tuberculosis (TB) after a negative screening have been reported, leading to the suggestion that improved TB testing is necessary.  The aim of the current study is to establish the incidence of TB and its characteristics in patients with inflammatory bowel disease (IBD) under TNF antagonists to design improved prevention strategies.  IBD patients from a single center treated with anti-TNF therapy between January 2000 and September 2011 were identified through a database that prospectively records clinical data, treatments and adverse events.  During the study period 423 patients received anti-TNF therapy.  Screening for latent TB infection (LTBI) previous to anti-TNF treatment was positive in 30 patients (6.96%).  Seven patients (1.65%) developed TB while under anti-TNF treatment.  Six patients (five under immunosuppressant treatment) had a negative LTBI screening.  TST was positive in one patient not receiving immunosuppressants, and was treated with isoniazid before starting anti-TNF therapy.  In 4 patients TB was diagnosed within the first 16 weeks after starting anti-TNF therapy.  Three cases had pulmonary TB and 4 extrapulmonary disease.  In the IBD population under study, incidence of TB infection associated with anti-TNF therapy is higher than that reported in controlled trials and occurs early after treatment initiation.  False negative results of LTBI despite appropriate measures may occur, suggesting that more effective screening strategies are needed.