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Non-tuberculous and tuberculous mycobacteria prevalence and drug susceptibility in Italian and foreign subjects: a monocentric observational study

S Caldrer(1) E Pomari(1) A Carrara(1) A Ragusa(1) L Nicolini(1) R Paola(1) P Cattaneo(1) N Ronzoni(1) A Angheben(1) A Angheben(1) F Gobbi(1,2) F Perandin(1)

1:IRCCS Sacro Cuore - Don Calabria Hospital, Negrar di Valpolicella (Verona), Italy; 2:Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy.

Mycobacterium tuberculosis (MTB) and non-tuberculous mycobacteria (NTM) can lead to both pulmonary and extra-pulmonary diseases. Despite the increasing identification of NTM, there is limited data on their circulation in Italy. This study aimed to determine the prevalence of mycobacterial infections among patients at Sacro Cuore - Don Calabria Hospital (Verona, Italy) from January 2020 to December 2023. Patients were categorized by geographic origin and age. Molecular methods were used for MTB and NTM identification, and drug susceptibility was evaluated by the minimum inhibitory concentrations (MICs) test.

Out of 2401 samples analyzed, 84% were from Italian individuals (median age 72 years) and 16% were from foreign individuals (median age 42 years). Real-time PCR revealed that 7.6% of samples tested positive for Mycobacteria: 93 for MTB and 91 for NTM. NTM species identified included: 43 M. avium, 14 M. intracellulare, 9 M. gordonae, 9 M. chimaera, 3 M. xenopi, 2 M. fortuitum, 2 M. abscessus, 2 M. kamsasii, and 1 each of M. celatum, M. chelonae, M. porcinum, M. mucogenicum, M. simiae, M. kumamotonensis, and M. malmoense. Notably, 35% of MTB and 88% of NTM-positive samples originated from Italian patients, whereas 65% of MTB and 12% of NTM-positive samples were from foreign individuals. The drug suscettibility were then analyzed on MTB and NTM coltures.

Due to the challenge of identifying and treating NTM infections owing to their intrinsic drug resistance, comprehensive monitoring of their epidemiology is crucial to update microbiological and clinical guidelines in our region.

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