Survey on the Phenotypic Variability of Pseudomonas aeruginosa in Cystic Fibrosis

Abstract

Cystic fibrosis (CF) is one of the most common autosomal recessive genetic disorders, resulting in faulty chloride ion channels in the lungs. As a result, the lungs are severely compromised with viscous secretions leading to chronic and repeated infections, and the colonization of a diverse microbial community. Pseudomonas aeruginosa is one of the primary pathogens in the CF lung and prior research has demonstrated a high degree of phenotypic heterogeneity among adult isolates in comparison to control strains. This study has two aims: First, the creation of an open repository of sputum and isolates collected from the Oklahoma Cystic Fibrosis clinic in Oklahoma City, OK to serve as a resource for research groups to use in polymicrobial studies. Second, the assay for a number of virulence factors using a subset of P. aeruginosa CF isolates recovered from two patients in each age category: children (under 13), adolescents (13-18), and adults (over 18). The collected repository includes sputum samples from 57 patients demonstrating a wide range of recoverable growth and a broad diversity of observed colony morphologies on nutrient and selective media. Thirty isolates per patient were assayed for surface motility (swim, swarm, and twitch) and production of hydrogen cyanide, biosurfactant, casein proteases, elastases, siderophores, and fluorescent pigments. P. aeruginosa isolates from most patients showed a high degree of consistency in producing hydrogen cyanide, fluorescent pigments, casein proteases, elastases, siderophores, and biosurfactant. There was, however, variability seen in the different surface motilities of isolates between the different age groups. These results provide insights to the variability of P. aeruginosa between age groups and confirm differences between P. aeruginosa isolated from newly infected CF patients and those chronically infected for many years. Further characterization and deeper understanding of the polymicrobial community in the CF lung are required to improve clinical diagnosis and treatment.