HIV-negative pulmonary disease caused by nontuberculous mycobacteria in Southern Brazil: clinical and microbiological characterization

Abstract

Background: Nontuberculous mycobacteria (NTM) have been identified with increasing frequency in the clinical practice. The aim of this study was to characterize NTM isolates in respiratory specimens from patients with pulmonary disease and to correlate this with clinical/radiological findings, decision to start treatment and outcomes. Methods: A cross-sectional descriptive study was performed and included all patients who had at least one NTM isolated in respiratory specimens between 2011 and 2014. NTM culture was performed in liquid medium followed by immunochromatographic identification (anti-MPT64). Species identification was based on nucleic acid amplification followed by restriction analysis of a 441 bp fragment of the hsp65 gene (hsp65 PRA) and patients' records were reviewed. Results: From 14,394 cultures in 4 years, 590 (4.10%) grew NTM and 305 (51.7%) isolates were characterized till species level, representing 290 patients including those with and without human immunodeficiency virus (HIV) infection. Two hundred and eleven non-HIV patients had NTM isolated from respiratory specimens, 49 (23.2%) had criteria for active disease based on the American Thoracic Society (ATS) 2007. The majority was men above 51 years old and M. intracellulare was detected in 59.2% (29/49), followed by M. avium 14.3% (7/49), and M. abscessus 12.2% (6/49). Conclusions:Old age, nodular and nodular/bronchiectasis radiographic pattern, previous tuberculosis (TB) treatment and M. intracellulare were more frequent among NTM-disease patients compared to those only colonized. Positive culture and maintenance of clinical symptoms (poor outcome) was a rule when M. abscessus caused NTM-disease. Positive acid-fast smear in respiratory specimen is a strong predictor of disease.

Molecular characterization of nontuberculous Mycobacteria in a tuberculosis and HIV reference unit in the State of Amazonas, Brazil

“…In addition, species implicated in pulmonary disease were also identified: M. avium and M. abscessus 6 , 18 . With regard to the potentially pathogenic NTM species, the findings of this study are similar to that of clinical practice and other studies carried out worldwide, with the most common species being M. avium , M. intracellulare , M. kansasii , M. chelonae , M. abscessus , M. fortuitum , and M. peregrinum 19 - 21 .…”

“…Another important aspect with respect to the frequency of NTM in patients with HIV in this study was the fact that 16% of the NTMs isolated in these patients were identified as Mycobacterium sp, which highlights the need to validate the rapid laboratory methods, preferably molecular methods, which can identify NTM 8 , 19 .…”

Epidemiological profile and follow-up of patients with pulmonary disease by non-tuberculous mycobacteria in Baixada Santista area, São Paulo

“…Recently, studies have been frequent in non-HIV-infected patients with Mycobacterium intracellulare (59.1%) and M. avium (14.3%) species as the most isolated. (28) It is important to highlight that, among the potentially pathogenic species, those belonging to the M. avium and M. kansasii complex (slow-growing mycobacteria) are the most commonly isolated, and both cause mainly pulmonary infection, the former being frequently responsible for disseminated disease and death in HIV-positive patients. (18,23,29) By analyzing only patients with confirmed cases of NTMPD, our results showed that, if we evaluate the data independently of HIV serology, M. kansasii still remains the most commonly isolated species (37.5%), followed by MAC (20.8%) and M. fortuitum (12.5%).…”

Identification of nontuberculous mycobacteria species by multiplex real-time PCR with high-resolution melting

“…In Brazil, a country with high endemicity for TB (20 th position according to WHO classification), the prevalence and incidence of NTM infections are not well known since the disease does not require compulsory notification for the health system. The isolation of NTM species in Brazil differs according to the region; however, it is possible to observe a predominance of Mycobacterium avium complex (MAC), such as M. avium , and M. intracellulare , M. kansasii , and M. fortuitum , causing active NTM disease 1 , 9 , 10 .…”