Evaluating differences in tuberculosis and nontuberculous mycobacterial lung disease in Florida

Currently, very little data exists that compare the features of pulmonary nontuberculous mycobacteria (NTM) and Mycobacterium tuberculosis (TB). Both have similar symptomology and analogous preliminary laboratory results, as both present with positive acid-fast bacilli stains. The objective of this study was to provide data that would help guide clinicians in their decision making regarding isolation precautions for patients, with a preliminary positive result for mycobacteria, prior to species identification.

We conducted queries for patients who had positive respiratory cultures for mycobacteria via our electronic medical record system, between January 1, 2011, and December 31, 2017. Additionally, we collected demographic and medical history, clinical presentation, and radiographic findings. The 2-sample unpaired Student t test, the Χ² test, and logistic regression were used to compare each group.

Through logistic regression, 8 variables were significantly associated with patients who grew either TB or NTM. History of incarceration, born outside of the United States, cavitation, and lymphadenopathy were associated with TB; tobacco smoke exposure, pre-existing lung disease, immunosuppression, and bronchiectasis were associated with NTM. Incidence of HIV and hemoptysis was not significantly different between the 2 groups.

Through the use of our study findings, improper use of airborne isolation precautions may be reduced or avoided.