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. 2019 Jul 3:12:1917-1927.
doi: 10.2147/IDR.S214181. eCollection 2019.

Evaluating the clinical significance of nontuberculous mycobacteria isolated from respiratory samples in Iran: an often overlooked disease

Zahra Mortazavi  1 , Ahmadreza Bahrmand  2 , Fatemeh Sakhaee  2 , Reza Hosseini Doust  1 , Farzam Vaziri  2   3 , Seyed Davar Siadat  2   3 , Abolfazl Fateh  2   3
Affiliations

Evaluating the clinical significance of nontuberculous mycobacteria isolated from respiratory samples in Iran: an often overlooked disease

Zahra Mortazavi et al. Infect Drug Resist. .

Abstract

Purpose: Nontuberculous mycobacteria (NTM) infection is an increasing problem worldwide whose clinical significance is still largely unknown. The aim of this study was to investigate the epidemiology of NTM infection from respiratory samples and to determine their clinical significance.

Patients and methods: This cross-sectional study was performed on 7,825 clinical samples from December 2015 to December 2017. Detection was conducted using phenotypic and genotypic (hsp65 PCR-RFLP, rpoB, and 16S rRNA genes sequencing) methods. All clinical information including symptoms and radiological findings was extracted from patients' records.

Results: A total of 478 were confirmed to have respiratory samples which were culture positive for mycobacteria, with the prevalence of NTM infection obtained as 53 (11.1%). Overall, Mycobacterium (M.) fortuitum was the most frequent NTM isolate, followed by M. simiae, M. kansasii, M. gordonae, and M. conceptionense. There was a relationship between NTM isolates and gender (P=0.039), symptoms (P=0.048), and radiographic findings (P=0.013). Bronchiectasis, infiltration, and cavitary lesion were the most frequent radiological findings in M. fortuitum, M. simiae, and M. kansasii, respectively, with cough being the most frequent symptom.

Conclusion: We reported five different NTM isolates in respiratory samples with a high frequency of M. fortuitum. NTM infections may play an important role in causing pulmonary disease and in tuberculosis management in endemic settings. Nevertheless, more studies are required to further examine the clinical significance of NTM isolates.

Keywords: Mycobacterium fortuitum; clinical significance; nontuberculous mycobacteria; respiratory samples.

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Conflict of interest statement

The authors report no conflicts of interest in this work.

Figures

Figure 1
Figure 1
Population study flowchart. Abbreviations: TB, tuberculosis; MTC, Mycobacterium tuberculosis complex; NTM-LD, nontuberculous mycobacteria lung disease; ATS, American Thoracic Society.
Figure 2
Figure 2
Symptoms of patients infected with nontuberculous mycobacteria (NTM) isolates.
See this image and copyright information in PMC

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