Prevalence and clinical outcomes of nontuberculous mycobacteria in a Brazilian cystic fibrosis reference center.

Nontuberculous mycobacteria (NTM) have been well established as an opportunistic pathogenic bacterial group for cystic fibrosis (CF) patients, with a prevalence ranging from 3% to 23% worldwide. A myriad of factors can bias the prevalence rate in different CF centers, especially misdiagnosis as systematic screening for NTM are still lacking in a number of centers. Here, we evaluated the presence and clinical outcomes of NTM isolation in microbiological respiratory cultures from CF patients attending a Brazilian reference center after setting up a systematic diagnostic protocol. Of 117 patients with respiratory samples cultured for NTM research, we found seven patients (6%) with at least one positive result for NTM [four males (57.1%), median age = 21 years (9-58)]. These cases are reported one-by-one. Median FEV1 was 40%, all patients showed signs of lung deterioration, with a median number of pulmonary exacerbations of three per patient/year. However, the impact of NTM isolation remains unclear in our center as all patients were coinfected with other CF respiratory pathogens. Our NTM prevalence assimilates to the lowest levels reported in literature, which is possibly influenced by the routinely applied Bacille Calmette-Guérin vaccine.

Secretory IgA response against Pseudomonas aeruginosa in the upper airways and the link with chronic lung infection in cystic fibrosis.

We assessed the diagnostic ability of an enzyme-linked immunosorbent assay test for measurement of specific secretory IgA (sIgA) in saliva to identify cystic fibrosis (CF) patients with Pseudomonas aeruginosa chronic lung infection and intermittent lung colonization. A total of 102 Brazilian CF patients and 53 healthy controls were included. Specific serum IgG response was used as a surrogate to distinguish CF patients according to their P. aeruginosa colonization/infection status. The rate of sIgA positivity was 87.1% in CF chronically infected patients (median value = 181.5 U/mL), 48.7% in intermittently colonized patients (median value = 45.8 U/mL) and 21.8% in free of infection patients (median value = 22.1 U/mL). sIgA levels in saliva were significantly associated with serum P. aeruginosa IgG and microbiological culture results. The sensitivity, specificity, PPV and NPV for differentiation between presence and absence of chronic lung infection were 87%, 63%, 51% and 92%, respectively. Measurement of sIgA in saliva may be used for screening patients in risk of developing P. aeruginosa chronic lung infection in CF and possibly also for paranasal sinusitis, and, most importantly, to efficiently rule out chronic P. aeruginosa lung infection.