Airway Microbiota in Bronchoalveolar Lavage Fluid from Clinically Well Infants with Cystic Fibrosis.

Background: Upper airway cultures guide the identification and treatment of lung pathogens in infants with cystic fibrosis (CF); however, this may not fully reflect the spectrum of bacteria present in the lower airway. Our objectives were to characterize the airway microbiota using bronchoalveolar lavage fluid (BALF) from asymptomatic CF infants during the first year of life and to investigate the relationship between BALF microbiota, standard culture and clinical characteristics.

Methods: BALF, nasopharyngeal (NP) culture and infant pulmonary function testing data were collected at 6 months and one year of age during periods of clinical stability from infants diagnosed with CF by newborn screening.

The arginine decarboxylase pathways of host and pathogen interact to impact inflammatory pathways in the lung.

The arginine decarboxylase pathway, which converts arginine to agmatine, is present in both humans and most bacterial pathogens. In humans agmatine is a neurotransmitter with affinities towards α2-adrenoreceptors, serotonin receptors, and may inhibit nitric oxide synthase. In bacteria agmatine serves as a precursor to polyamine synthesis and was recently shown to enhance biofilm development in some strains of the respiratory pathogen Pseudomonas aeruginosa.