psk1 virulence gene-induced pulmonary and systemic tuberculosis in a young woman with normal immune function: A case report.

Abstract

Background: Tuberculosis is a chronic infectious disease and an important public health problem. Despite progress in controlling tuberculosis, the incidence of tuberculosis in China is still very high, with 895000 new cases annually. This case report describes the investigation of a case of severe disseminated tuberculosis in a young adult with normal immune function, conducted to ascertain why a Mycobacterium tuberculosis (M. tuberculosis) strain caused such severe disease.

Case summary: A previously healthy 28-year-old woman presented to our hospital with a 1-month history of fever and fatigue. She was diagnosed with severe disseminated pulmonary tuberculosis, spinal tuberculosis with paravertebral abscesses, and tuberculous meningitis. M. tuberculosis was isolated from bronchoalveolar lavage fluid. She was treated with standard antituberculous therapy and underwent debridement, bone graft, and internal fixation surgery for spinal tuberculosis. She responded to therapy and regained her ability to walk following the surgery. We analysed the whole-genome sequence of the strain and designated it BLM-A21. Additional M. tuberculosis genomes were selected from the Virulence Factor Database (http://www.mgc.ac.cn/cgi-bin/VFs/genus.cgi?Genus=Mycobacterium) for comparison. An evolutionary tree of the BLM-A21 strain was built using PhyML maximum likelihood software. Further gene analysis revealed that, except for the pks1 gene, BLM-A21 had similar virulence genes to the CDC 1551 and H37Rv strains, which have lower dissemination.

Conclusion: We speculate that the pks1 virulence gene in BLM-A21 may be the key virulence gene responsible for the widespread dissemination of M. tuberculosis infection in this previously healthy adult with normal immune function.