The present case demonstrates an atypical pulmonary mycobacteriosis that mimicked classical symptoms and radiology findings for tuberculosis. While T-SPOT Test and PCR analyses proved negative for tuberculosis, microscopic sputum evaluation showed acid-fast bacilli and Mycobacterium celatum was found in culture. Uniquely, in our case M. celatum was resistant to rifabutin. Therefore, after not responding to combination treatment including rifabutin, our patient was treated with ethambutol, clarithromycin and protionamide. Classical risk factors for atypical mycobacteriosis such as immunodeficiency (including medication-induced), preexisting pulmonary disease or multimorbidity were not present. We conclude that the high age of the patient (92 y) may have been the main contributing factor for the infection.