P41

The gold standard for diagnosing of both Tuberculosis (TB) and non-tuberculous mycobacteria (NTM) infection is the culture of clinical samples, typically contaminated with normal flora that can overgrow and prevent the detection of mycobacteria. Therefore, the decontamination of specimens is a crucial step to maximize mycobacterial yield. However, the need to store samples after decontamination could decrease the viability of mycobacteria, resulting in a negative diagnostic result.

The study aims to evaluate the viability of Mycobacteria after the decontamination process,  stored up to 14 days, before culture.

For this purpose, we chose a toti-S MTBc and a M. gordonae clinical strain. Four mycobacteria sputum-negative samples were spiked with 1,500 CFU and 15,000 CFU of MTB and  M. gordonae, respectively. After decontamination step using the MycoTB™ kit (Copan Italia, Brescia), samples were resuspended in 4 mL of resuspension solution included in the kit and cultured in a liquid (MGIT) and in a solid media (Lowenstein-Jensen, LJ) at:  T0 –immediately after decontamination;  T1 – 48 hours after decontamination;  T2 – 7 days after decontamination;  T3 – 2 weeks after decontamination. Samples were stored at 4°C before culture.

Preliminary results show no differences between T0 and T1 in term of time-to-positivity (TTP) in MGIT and in the number of CFUs in LJ for both TB and NTM in all cultured samples (1,500 and 15,000 CFU respectively). Tests at T2 and T3 are currently ongoing. The final results will be illustrated in the poster.