Carbohydrate sulfation effects on growth of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a key player in the pathology and morbidity of cystic fibrosis. Chronic obstructive pulmonary disease, which results from the most common and severe mutations in this genetic disorder, typically includes chronic infection with P. aeruginosa which, even with rugged antibiotic and physical therapy regimens, is rarely eradicated. It is not known whether the increased oligosaccharide sulfation characteristic of cystic fibrosis tracheobronchial mucins plays a role in the survival of P. aeruginosa in the airway. In this study, sulfated monosaccharides were synthesized and tested for their effects on the growth of clinical isolates and laboratory strains of this organism when supplied as the sole carbon source in vitro. Carbohydrate sulfation was observed to reduce, but not prohibit, growth of P. aeruginosa on carbohydrates normally utilized in their nonsulfated form. The various sulfated sugars employed as the sole carbon source gave characteristic and consistent growth profiles and maximum growth values across the strains tested. P. aeruginosa isolates from patients with cystic fibrosis often express a mucoid phenotype, which is thought to contribute to their ability to survive in harsh conditions. Carbohydrate sulfation effects on growth did not differ significantly between mucoid and nonmucoid strains. These results suggest that the additional sulfation of tracheobronchial mucin documented in cystic fibrosis may in fact contribute to the mucin's resistance to utilization by P. aeruginosa and potentially other pathogens, providing an additional level of host protection, and limiting the available nutrient pool and thereby bacterial growth.