Computed Tomography Findings of Pulmonary Mycobacterium simiae Infection

Abstract

Nontuberculous mycobacterial (NTM) pulmonary infections can be quite similar to tuberculosis, both clinically and radiologically. However, the treatment protocol is not similar. Mycobacterium simiae is a rare cause of NTM pulmonary infection. Herein, we aimed to evaluate and compare the computed tomography (CT) scan findings of M. simiae infection in lungs. For this reason, thirty-four patients (n = 34) with M. simiae lung infection were retrospectively evaluated. Diagnosis was confirmed by American Thoracic Society (ATS) guidelines and CT scans were reviewed in both lung and mediastinal windows. The average age of patients was 63 ± 14.54 years and 52.9% were male. The majority of patients had cough (91.2%) and sputum production (76.5%). Clinically, 41.2% of patients had previous history of TB (14/34), 38.2% had cardiac diseases (13/34), and 35.3% had diabetes mellitus (12/34). The most common CT findings in our study were nodular lesions (100%) and bronchiectasis (85.29%). Regarding the severity, grade I bronchiectasis was the most prevalent. Other prominent findings were tree-in-bud sign (88.2%), consolidation (52.94%), and lobar fibrosis and volume loss (67.6%). There was no significant zonal distribution of findings. In conclusion, nodular lesions and bronchiectasis are the most frequent features in CT scan of M. simiae pulmonary infection.

Clinical, Radiological, and Microbiological Characteristics of Mycobacterium simiae Infection in 97 Patients

“…As reported elsewhere (7,15), clinical signs of infection among our cohort patients were mostly respiratory symptoms such as productive cough. Our study confirms the findings of van Ingen et al 7, with patients who lost weight being significantly more likely to meet the ATS diagnostic criteria.…”

“…Micronodular lesions were the most common radiological findings and were associated with ATS criteria for M. simiae in the multivariate analysis. Cavitary lesions were present in 25.8% of our cohort patients, compared with studies that reported cavitary lesions in 3% to 15% of patients (11,15). Unlike in the study by van Ingen et al 7, cavitary lesions were not associated with ATS criteria for infection in our cohort.…”

“…To the best of our knowledge, this is the largest cohort of patients with clinical isolates of M. simiae reported in the literature to date (4,6,7,15). Reunion Island is a French overseas department located in the Indian Ocean, with a population estimated in 2016 to be more than 850,000 (Institut National de la Statistique et des Etudes Economiques, https://www.insee.fr/fr/statistiques/2018922).…”

Emergence of Mycobacterium simiae: A retrospective study from a tertiary care center in Lebanon

“…Baghaei et al showed that nodular lesions were found in 100% of patients, and bronchiectasis and cavities in 84% and 88%, respectively [ 15 ]. Furthermore, Baghizadeh et al showed that the most common findings were nodular lesions (100%), and bronchiectasis (85.29%), in addition to other findings such as para-tracheal and hilar lymphadenopathy (44%), pleural effusion (20.6%), and pleural thickening (58.8%) [ 21 ]. In the latter study, the right middle lobe was the most commonly involved (50%), followed by the lingula (47%), and the right upper lobe (41%) [ 21 ].…”

“…Furthermore, Baghizadeh et al showed that the most common findings were nodular lesions (100%), and bronchiectasis (85.29%), in addition to other findings such as para-tracheal and hilar lymphadenopathy (44%), pleural effusion (20.6%), and pleural thickening (58.8%) [ 21 ]. In the latter study, the right middle lobe was the most commonly involved (50%), followed by the lingula (47%), and the right upper lobe (41%) [ 21 ]. On the other hand, Shitrit et al noted cavitary disease in 3%, pulmonary infiltrates in 57%, and pleural effusion in 16%, along with involvement of the middle and lower lobes in 55% [ 1 ].…”