The patient is a 50-year-old white male, previous smoker (he smoked for 30 years, 45 pack-years, quitting 8 years ago), who worked in an underground emerald mine for 20 years, until 9 years ago, without proper use of personal protective equipment. He had a history of pulmonary tuberculosis treated with rifampin, isoniazid, and pyrazinamide for 2 months, followed by rifampin and isoniazid for 4 months, 11 years ago.
He attends a pneumology outpatient clinic due to silicosis and, as of 2013, a high-resolution computed tomography of the thorax already showed structural lung sequelae.
During follow-up, he developed a worsening of cough and expectoration pattern. Two sputum samples were positive for acid-fast bacilli [(+) and (++), resp.], and presumptive treatment for pulmonary tuberculosis was initiated with rifampin, isoniazid, pyrazinamide, and ethambutol. Mycobacteria culture was not performed at this moment. However, at month 5 of treatment, already in the continuation phase with rifampin and isoniazid, and despite correct medication intake and a slight improvement of symptoms, sputum bacilloscopy remained positive. A thorax computed tomography revealed large pulmonary opacities in the upper lobes of both lungs, with intermingled air bronchograms and calcifications, bilateral diffuse nodular infiltrates with areas of pleural thickening, and nodular interstitial infiltrate associated with ground glass opacities in the posterior segment of the inferior right lobe, as well as cavitations with thick walls, suggesting an active inflammatory process (Figure 1). Blood tests revealed a normal hemogram and renal and liver functions, and HIV, hepatitis B, and hepatitis C serologies were negative.
Sputum cultures were then performed and two were positive for NTM; while awaiting the identification of the species, empiric treatment with streptomycin, ethambutol, clarithromycin, and rifampin was instituted for Mycobacterium avium, the most frequently NTM isolated in our community. The patient had a greater improvement of his symptoms.
The species identification was performed by the Tuberculosis Bacteriology Laboratory from the Professor Helio Fraga Reference Center (Rio de Janeiro), the National Mycobacterium Reference Laboratory, using genetic sequencing of the 16S rRNA gene. The NTM species isolated was Mycobacterium sherrisii. The treatment regimen was once again adjusted, with the replacement of rifampin with rifabutin, inclusion of trimethoprim-sulfamethoxazole (TMP-SMX), and suspension of streptomycin after 2 months. A sensitivity test was not performed.
Currently, the patient is at month 9 of treatment, with only an occasional nonproductive cough, and with negative sputum bacilloscopies and cultures, which have been performed monthly, since month 2 of treatment.
It is our plan to complete 12 months of treatment with rifabutin, clarithromycin, ethambutol, and TMP-SMX, as of the first negative culture.