Nontuberculous Mycobacteria in Portugal: Trends from the last decade

Introduction and objectives: Nontuberculous mycobacteria (NTM) are opportunistic human pathogens found in the environment. The transmission seems to be associated with inhalation of aerosol droplets, ingestion or trauma events. Recent studies indicate that NTM disease is increasing worldwide, however, the true clinical impact of NTM infections is dif ficult to determine due to challenges in discriminating between disease and colonization as they are ubiquitous in the environment. In addition, understanding the epidemiology of NTM is dif ficult and has not yet been established. In this work, we used a country NTM representative collection from the National Reference Laboratory for Tuberculosis (NRL-TB) of the National Institute of Health (INSA), to characterize the circulation trends of NTM species in Portugal and the most affected regions, contributing to a better understanding of the NTM epidemiology. Material and methods: We conducted a nationwide retrospective study where all individuals with positive NTM cultures at the NRL-TB of the INSA from 2014 to December 2020 were included. Positive cultures were identi fied using GenoType Mycobacterium CM/AS (R) (Hain Lifescience) according to manufacturer 's instructions, or hsp65 DNA sequencing as previously described. Social-demographic data from patients were also analyzed and patients classi fied into 3 groups according only to microbiological data, "de finite NTM disease ", "NTM colonization " and, "possible NTM disease ". Results: In the period 2014-2020, the NRL-TB performed 50397 cultures. Among these, 1118 cultures were NTM positive retrieved from 944. Most of our cases were in patients whose mean age was 64 15.9 years, and no signi ficant differences between gender was observed, although more frequent in male patients. Overall, from the 944 cases, we were able to identi fied 93 "de finite NTM disease " cases and 79 "possible NTM disease ". Mycobacterium avium complex (MAC) (40,8%), Mycobacterium abscessus-chelonae complex (MABC) (9,6%) and Mycobacterium fortuitum (6,3%) were responsible for most of the infections. The geographical distribution of NTM cases varied signi ficantly and was possible to observe that was independent of population den- sity. The region were most cases occurred was Lisbon Metropolitan Area (31,9%), followed by North (25,3%) and Centre (24,4%), however North region has the highest number of "de finite NTM disease " cases (n=33). Conclusions: This is the first national wide epidemiological study on this subject, contributing to a better understanding of NTM dynamics in Portugal. MAC was the NTM species responsible for the majority of infections and, LMA the region with the highest number of cases. It was also possible to conclude that the number of NTM isolates is independent of the demography of the region. (c) 2022 Sociedade Portuguesa de Pneumologia. Published by Elsevier Espa & ntilde;a, S.L.U. This is an open access article under the CC BY -NC -ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).