Pilot Study on non-tuberculous mycobacteria infections in Italy

Abstract

Abstract Background The rise in non-tuberculous mycobacteria (NTM) diseases has been reported worldwide, but no major information is known for Italy. The purpose of this pilot study is to release nationwide data on distribution of NTM in our country. Methods In 2016, the Istituto Superiore di Sanità (National Institute of Health) began to collect microbiological, clinical and minimum inhibitory concentration (MIC) data on NTM infections, in collaboration with hospital laboratories located in 15 out of 20 regions (Studio Multicentrico Italiano NTM, SMI-NTM), which routinely isolate and characterize NTM by commercial identification (Genotype) and MIC (Sensititre) assays. Results In 2016-2018, 32 labs reported data on 4169 NTM strains, including 644 rapid growers (15%) and 3525 slow growers (85%). The most frequent species were Mycobacterium avium (MA) (29.2%), M. intracellulare (MI) (21.5%), M. xenopi (MX) (10.6%), M. gordonae (10.6%), M. abscessus (5.9%), M. chimaera (MC) (5.1%). Overall, 88% NTM strains were isolated from pulmonary sites, 84% from Italians, 51% from men. NTM infections in Italians occurred in 75-84 years old patients, while in foreign-born people were observed in 15-44 years old patients. Strains from cystic fibrosis were 11.9%. The MICs of clarithromycin (CLA) for MA or MI peaked at 2 µg/ml, while for amikacin (AK) peaked at 16 µg/ml. When MICs were interpreted according to the 2018 Clinical and Laboratory Institute Standards (CLSI) breakpoints, MA or MI resistances for CLA were 2.6% and 2.6% respectively, while for AK they were 7.2% and 4.5%, respectively. Higher resistance rates for MA and MI were observed for moxifloxacin and linezolid. MICs of MC, MX, M. kansasii, M. marinum and rapid grower NTM were also determined and interpreted on the basis of CLSI breakpoints. Conclusions This 3-years pilot study is the basis for a future multiannual national strategic plan for surveillance of NTM infections in Italy (collection of 2019 data is in progress). Key messages This 3-years pilot study is the basis for a future multiannual national strategic plan for surveillance of NTM infections in Italy. The purpose of this pilot study is to release nationwide data on distribution of NTM in our country.