Introduction:

Mycobacterium avium complex (MAC) is composed by a set of nontuberculous mycobacteria which are responsible for a growing number of pulmonary infections. This growth has paralelled their prevalence in household water sources, such as patient's showers.

Methodology:

Clinical records of Coimbra Hospital and University Centre patients with MAC isolates were reviewed regarding presence of infection and its clinical and prognostic features, over the course of 20 years.

Results:

A majority (76%) of MAC isolated were deemed infectious, the most commonly isolated mycobacteria being M. avium (78%). Microbiological diagnosis was invariably obtained by molecular testing and was cosubstantiated by culture in 38%. Sampling was obtained by bronchoalveolar lavage in 85% of cases.

Clinical presentation was dominated by bronchorrhoea, recurrent haemoptysis and B symptoms. A radiological nodular pattern occured in 69%, occasionally with cavitation. Bronchiectasis were found in a 25% and consolidation in 19%. A basal, bilateral distribution of radiological changes was observed. 

The entirety of patients were immunodeficient, either by comorbidity or immunosupression. End-stage HIV infection was the most common factor. Patients with lymphoproliferative disorders and auto-immune illness were also frequent. Half of the patients presented a form of parenchymal abnormality prior to infection, such as bronchiectasis.

Treatment was most frequently by rifampin, ethambutol and a macrolide. Relapse ocurred in 25%.

Discussion:

A growing burden of MAC infection, and its inerent morbidity in immunocompromised patients, may be in relation to an increase in its environmental prevalence.