Translocation of Mycobacterium tuberculosis after experimental ingestion

Human tuberculosis is a life-threatening infection following the inhalation of Mycobacterium tuberculosis , while the closely related bacteria Mycobacterium bovis and Mycobacterium canettii are thought to be transmitted by ingestion. To explore whether M . tuberculosis could also infect individuals by ingestion, male BALBc mice were fed 2 x 10 6 CFUs of M . tuberculosis Beijing or phosphate-buffered saline as a negative control, over a 28-day experiment. While eight negative control mice remained disease-free, M . tuberculosis was identified in the lymph nodes and lungs of 8/14 mice and in the spleens of 4/14 mice by microscopy, PCR-based detection and culture. Whole-genome sequencing confirmed the identity of the inoculum and the tissue isolates. In these genetically identical mice, the dissemination of M . tuberculosis correlated with the results of the culture detection of four intestinal bacteria. These observations indicate that ingested M . tuberculosis mycobacteria can translocate, notably provoking lymphatic tuberculosis.