A Bone marrow transplant recipient patient developed chest infection. On HRCT 'Tree in bud appearance' is seen. Most likely causative agent is -
The 'tree-in-bud' sign is visible in high-resolution computed tomography (HRCT) and it is characterized by small centrilobular nodules of soft-tissue attenuation, connected to multiple branching linear structures of a similar caliber, originating from a single stalk.this is the main feature of pneumocystis jerovicii Ref Harrison20th edition pg 1079.
Klebsiella
Pneumocystis
TB
RSV
Infection