Fast detection of non-tuberculous mycobacteria in medical device-water samples: evaluation of the STANDARD™ M10 MTB/NTM cartridge.

INTRODUCTION

Non-tuberculous mycobacteria (NTM) are environmental pathogens increasingly being recognized as a source of healthcare-associated infections, particularly through contaminated medical water systems such as heater-cooler units and haemodialysis machines. The rising prevalence of NTM-related diseases underlines the urgent need for enhanced surveillance with more effective and rapid diagnostic tools. This study aimed to compare the performance of the STANDARD™ M10 MTB/NTM, a novel cartridge-based real-time PCR assay for detecting NTM in environmental water samples, with conventional mycobacteria growth indicator tube (MGIT) liquid culture.

METHODS

In accordance with the Emilia-Romagna surveillance programme, water samples from medical devices were processed using standard culture methods for NTM detection. The remaining decontaminated samples were stored at -20 °C. For this study, 150 stored aliquots were selected and tested with STANDARD™ M10 MTB/NTM assay.

FINDINGS: NTM were detected by culture in 37/150 (24.7%) samples, with Mycobacterium chimaera and Mycobacterium saskatchewanense being the most frequently isolated species. The STANDARD™ M10 MTB/NTM assay detected 32/37 culture-positive samples, and tested negative in all (N =113) culture-negative samples, corresponding to a sensitivity of 86.5% (95% CI: 0.72-0.94) and a specificity of 100% (95% CI: 0.97-1.00), with a strong concordance (κ = 0.90).

CONCLUSIONS

Compared with culture, STANDARD™ M10 MTB/NTM assay proved to be a reliable and rapid tool for detecting NTM in environmental water samples, demonstrating high specificity and predictive value. Its implementation could support more timely and comprehensive environmental monitoring, helping to prevent the spread of these pathogens and reducing the risk of nosocomial infections.