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Epidemiology of infections caused by Tuberculous and Non-Tuberculous Mycobacteria in the province of Pavia: a 12-year comparative analysis

M Siciliano(1) V Monzillo(2) J Bagnarino(1) G Petazzoni(1) P Cambieri(1) F Baldanti(1)

1: U.O.C. Microbiologia e Virologia, Dipartimento Medicina Diagnostica, Fondazione IRCCS Policlinico San Matteo, Pavia, 27100, Italy; 2:Dipartimento di Medicina Interna e Terapia Medica, Università degli Studi di Pavia, Pavia, 27100, Italy

Mycobacteria pulmonary diseases cause significant morbidity and mortality to human health. Although Tuberculosis (TB) remains a serious public health problem, the prevalence of lung diseases caused by Non-Tuberculous Mycobacteria (NTM) is increasing worldwide. Our study aims to illustrate the 12-year epidemiological changes of NTM and Mycobacterium tuberculosis complex (MTC) infection in the province of Pavia. The study was performed on 437 biological samples positives for MTC and 345 positives for NTMs, from 2011 to 2022. All samples were decontaminated with MycoTB™, according to current guidelines. Isolation and identification of strains were carried out with BACTEC MGIT™ 960 and GenoType AS/CM/NTM-DR/MTBC/GeneXpert, respectively. Patients were considered incident in the year in which they became culture positive. Our data showed a sharply increasing trend over the years of NTMs compared to MTC, which have declined, both for pulmonary and extra-pulmonary diseases. As regard pulmonary disease, MTC were isolated in 56% of cases, while NTM most frequent isolates were Mycobacterium avium complex (MAC) (n=152; 25,7%), M. abscessus complex (n=22; 3,7%) M. xenopi (n=23; 3,9%), M. fortuitum (n=8; 1,4%), M. chelonae (n=8; 1,4%) and M. kansasii (n=8; 1,4%). We also evaluated the distribution by age groups (0-18, 19-64, >65 years). MTC pulmonary infections were more frequent in 19–64-year-old, while those sustained by NTM were more widespread in over 65 year-patient. The increased trend for NTM could in part be explained by the rise of aged population with lung diseases such as BPCO and bronchiectasis, the employment of immunosuppressive drugs and the development of diagnostic techniques.

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