Coinfections of Mycobacterium tuberculosis and Non-Tuberculous Mycobacteria species: perspective from a Reference Centre case series

Introduction In previous publications there are only a few case reports about co-infections between Non tubercular mycobacteria (NTM) and Mycobacterium tuberculosis (MT). This case series investigates the clinical presentation and outcome in patients with mycobacterial coinfections. Methods In this monocentric retrospective observational study we collected data on 21 patients coinfected with two different mycobacteria managed in our centre. Patients were divided in two cohorts: 8 patients with MT and NTM coinfection (MT cohort) and 13 coinfected with two species of NTM (NTM cohort). Results In the MT cohort, mostly was found M. abscessus(25%). After the end of MT therapy, 4 (50%) patients did not report any symptom and none showed signs of NTM related disease. Follow up CT scans showed only 2 patients (25%) with restitutio ad integrum. In the NTM cohort the most frequent pathogen was M. avium (84.6%). After the end of therapy 7 patients ended up with microbiological clearance while 4 patients experienced the recurrent isolation of 2 samples positive for previously treated NTM. Among them only 1 patient underwent a new treatment cycle. Radiological follow up showed 2 patients (15.3%) with restitutio ad integrum. The two different sub-groups differ in terms of compliance of therapy (100% completed the therapy for MT vs 53.8% for NTM), clinical status (50% without symptoms after therapy in MT group vs 23% in NTM group) and radiological outcome (15.3% with normal imaging in the NTM cohort vs 25% in the MT one). Our study underlines the need of consensus guidelines and that an expert consultation should be sought in formulating the treatment.