Burden of potentially novel species of non tuberculosis mycobacteria in Iranian tuberculosis laboratories

AbstractAims and objectivesNontuberculous mycobacterium (NTM) infections are caused by mycobacteria that are found in water and soil. The chances of missing NTM species are higher in tuberculosis endemic countries like Iran, which are poorly equipped and overburdened with other diseases. The aim of this study is to access the diversity of rare, unusual and frequent species in Iranian tuberculosis laboratories.MethodsFrom 2012–2014 a total of 243 different clinical isolates of NTM were recovered from Mycobacteriology Reference Laboratories across Iran (Ahvaz, Esfahan, Tehran, Gorgan, Kermanshah). The isolates identified by rpoB gene sequencing are useful markers in mycobacterium identification.ResultsBased on rpoB gene sequencing, 20 groups do not belong to any of the officially recognized mycobacteria. A total of 210 isolates of NTM were identified to species level, including M. fortuitum (66), M. kansasii (20), M. simiae (20), M. conceptionense (10), M. peregrinum (9), M. thermoresistibile (9), M gordonae (8), M. lentiflavum (8), M. phlei (6), M. intracellulare (6), M. abscessus subsp. abscessus (5), M. chelonae (5), M. abscessus subsp. bolletii (4), M. avium (4), M. flavescents (4), M. nonchromogenicum (4), M. terrae (4), M. branderi (3), M. iranicum (3), M. mucogenicum (3), M. scrofulaceum (3), M. smegmatis (3) and M. triplex (2).Among all isolates, M. fortuitum was identified as the most frequent encounter (27%) of NTM, and M. kansasii and M. simiae were the second most dominant species (8.2%) among the isolates. A total of 33 isolates (13%) were unidentifiable to species level. M. fortutium was the most frequent species in Ahvaz, Esfahan, Tehran and Gorgan, but M. simiae was the most frequent species in Kermanshah. Thirty-three isolates (20 groups) presented unique genetic features. Further molecular tests should be carried out to reliable identification of these isolates to species level.ConclusionsThe present study provides evidence for the importance of NTM identification in the clinical setting and the presence of diverse species in clinical samples as a causative agent of disease.The presence of diverse species of NTM and unidentifiable strains in a clinical setting in Iran emphasizes the use of sequence analysis of genes for reliable identification

“Multidrug-resistant tuberculosis” may be nontuberculous mycobacteria

Multidrug resistant tuberculosis (MDR-TB) presents a great challenge to public health, especially for developing countries. Some nontuberculous mycobacteria (NTM) cause the similar clinical and radiological characteristics with tuberculosis. We aimed to identify the frequency of NTM infections among subjects who were suspected to have MDR-TB due to lack of response to anti-TB treatment. This retrospective study evaluated patients with suspected MDR-TB due to lack of sputum conversion after 2–3month therapy with first line anti-TB treatment from 2009 through 2014. Cultures for mycobacteria were performed and identification was done to species level by phenotypic and molecular tests. The outcome of the patients with NTM disease and related risk factors for poor outcome were evaluated. Out of 117 consecutive strains isolated from suspected MDR-TB subjects, 35 (30%) strains were identified as NTM by using conventional and molecular approaches. Of these patients with positive NTM cultures, 32 (27%) patients met ATS/IDSA diagnostic criteria. Out of 32, 29 (90%) individuals with confirmed NTM diseases had underlying disorders including 8 subjects with malignancy, 5 with organ transplantations, and 4 with the human immunodeficiency virus. No known underlying disorder was found in 3 (9%) subjects. Treatment outcomes were available for 27 subjects, 17 (63%) of whom were cured and 10 (37%) had poor outcome including 6 (60%) who failed and 4 (40%) who died during treatment. The high costs to the patient and society should lead health care providers to consider NTM in all patients suspected of having TB. •NTM may cause the similar presentation with tuberculosis.•NTM may misdiagnose with drug resistant tuberculosis (MDR-TB).•Universal mycobacterial culture and molecular identification is recommended