Nontuberculous mycobacteria isolated from specimens of pulmonary tuberculosis suspects, Northern Tunisia: 2002–2016

Abstract

Background Reports on the worldwide ascending trend of pulmonary nontuberculous mycobacteria (NTM) isolation rates and their effective role in respiratory tract infections are compelling. However, as yet, there are no such data relating to Tunisia. Methods Here we carried out a retrospective review of mycobacterial cultures originating from Northern Tunisia, which have been processed in the laboratory of mycobacteria of the Institut Pasteur de Tunis, during the time period 2002–2016. All pulmonary NTM (PNTM) isolates available for culture were characterized phenotypically and their taxonomic status was further established based on polymorphisms in rpoB, 16S rRNA, hsp65, and sodA DNA gene sequences. Results Of the 10,466 specimens collected from HIV-negative Tunisian patients with presumptive clinical pulmonary TB, 60 (0.6%) yielded PNTM isolates. An overall annual PNTM isolation prevalence of 0.2/100,000 was estimated. As far as could be ascertained, this isolation rate accounts amongst the lowest reported hitherto throughout the world. Among the 30 NTM isolates that were available for culture, 27 (90.0%) have been identified to the species level. The most commonly encountered species was Mycobacterium kansasii (23.3%) subtype 1. Strikingly, all M. kansasii cases were male patients originating from Bizerte, an industrialized region particularly known for iron industry. The remaining NTM species were M. fortuitum (16.6%), M. novocastrense (16.6%), M. chelonae (10.0%), M. gordonae (6.6%), M. gadium (6.6%), M. peregrinum (3.3%), M. porcinum (3.3%), and M. flavescens (3.3%). There were no bacteria of the M. avium complex, the most frequently isolated NTM globally, and the main driver of the rise of NTM-lung diseases. Conclusions This study uncovered an exceptional low prevalence of PNTM isolation among HIV-negative TB suspects in Northern Tunisia, suggesting a very low burden of NTM pulmonary disease. However, the frequent isolation of M. kansasii subtype 1, the most pathogenic subtype, particularly from the industrialized region of Bizerte, strongly suggests its effective involvement in a typical pulmonary disease.

Phenotypic and genomic hallmarks of a novel, potentially pathogenic rapidly growing Mycobacterium species related to the Mycobacterium fortuitum complex

“…Previously, we have described a putative new RGM species, referred to as TNTM28, isolated from the sputum of an apparently immunocompetent young man presenting with an underlying pulmonary disease 20 . Based on sequence polymoprphisms in 16 rRNA, hsp65 , and rpoB gene sequences, this non photochromogenic RGM was found to be related to the M. fortuitum complex.…”

Identification and characterization of nontuberculous mycobacteria isolated from suspected pulmonary tuberculosis patients in eastern china from 2009 to 2019 using an identification array system

“…It is worth noting that M. kansasii is also commonly isolated in many countries or regions. Remarkably, the isolation rate of this pathogen from NTM pulmonary diseases in Norther Tunisia was particularly high, reaching 23.3% of total NTM isolations, 23 as compared with the observed rates in Japan (3.9%) 28 and USA (7.7%). 29 Pulmonary disease caused by M. kansasii tends to cluster in specific geographical locations, with Central Europe being one of the hotspots.…”

“… 22 However, the proportion of NTM in suspected pulmonary TB varies greatly between different countries or regions: 0.6% (60/10,466), 2.5% (43/2,036), 7.1% (68/958) and 15.1% (62/410) in Northern Tunisia, Ghana, Korea and Iran, respectively. 13 , 20 , 23 , 24 Thus, the species distribution of NTM isolates and the types of diseases caused by NTM species vary per region. 25 , 26 …”

“…Another NTM species that shows a remarkable difference in isolation frequency is MABC, which is common in Korea, 24 China, 21 , 22 , 27 Japan, 28 USA, 29 and Ghana 13 but less frequent Northern Tunisia 23 and Iran. 20 MABC is a RGM that is responsible for opportunistic pulmonary infections in patients with structural lung disorders, such as cystic fibrosis and bronchiectasis, as well as a wide range of skin and soft tissue infections in humans.…”

Nucleic acid amplification techniques for rapid diagnosis of nontuberculous mycobacteria: A protocol of systematic review and meta-analysis

“…Acid-fast bacilli (AFB) smear does not possess the ability to differentiate between NTM and MTB infections. Conventional diagnosis of NTM requires the results of Mycobacterium culture before species identification, and Mycobacterium culture takes several weeks and sensitivity is still at the low side [6]. Mycobacterium culture does not comply with the need for early and rapid diagnosis for NTM.…”