Nontuberculous Mycobacteria Isolates in Respiratory Samples and Mycobacterial Pulmonary Disease in an Area of Northern Spain

Introduction

The epidemiology of nontuberculous mycobacteria (NTM) is not well known. In this study, we aimed to determine the incidence of NTM isolates and nontuberculous mycobacterial pulmonary disease (NTM-PD) in five closely located hospitals in an area of northern Spain and analyse differences between them.

Material and methods

Demographic, microbiological, clinical and radiological data were collected retrospectively from all patients with a NTM isolated from respiratory specimens at five hospitals between 2012 and 2019. Mycobacterium gordonae isolates were excluded. Once the data was collected, it was determined which patients met the NMT-PD criteria.

Results

594 patients were included in the study. The mean incidence rate of NTM isolates across all five hospitals in the period studied was 4.15 per 100,000 person-year, while the rate of NTM-PD was 1.2. The annual number of isolates showed an upward trend over this period, but the same did not occur in the number of cases of NTM-PD. The species most frequently isolated were Mycobacterium avium complex (MAC) and Mycobacterium xenopi and those most frequently causing disease were MAC and Mycobacterium kansassi. There were significant differences between the five centres.

Conclusions

Our results are in line with similar studies in Europe in terms of NTM isolation and NTM-PD incidence and species isolated; however, we do not see the upward trend in NTM-PD rates described elsewhere. The great variability in isolation and disease rates, as well as in species isolated in geographically close areas, underlines, in our opinion, the importance of local environmental factors.