PULMONARY EXPOSURE OF MICE TO ENGINEERED PSEUDOMONADS INFLUENCES INTESTINAL MICROBIOTA POPULATIONS

Microbial biotechnology applications have prompted research into their potential impacts on human health and the environment. In this study, a mouse model was used to evaluate indirect effects (e.g., alteration of the intestinal microbiota) of pulmonary exposure to representative biotechnology agents (Pseudomonas aeruginosa strain AC869 and Pseudom onas cepacia strain AC1100) selected for their ability to degrade haza rdous chemicals. CD-1(R) mice were challenged intranasally with approx imately 10(3) or 10(7) colony-forming units (cfu) of strain AC869 or 1 0(8) cfu of strain ACI 100. At time intervals, clearance of the microo rganisms and effects on resident microbiota were determined. When the low (10(3) cfu) dose was administered, strain AC869 was not recovered from the small intestine but was detectable in the cecum and lungs 3 h after treatment and persisted in the nasal cavity intermittently for 14 d. Treatment of animals with 10(7) CfU of strain AC869 resulted in detection 14 d following treatment. Strain AC869 challenge modified th e small intestinal anaerobe count and cecal obligately anaerobic gram- negative rods (OAGNR) and lactobacilli. Following exposure, Pseudomona s cepacia strain AC1100 persisted in the lungs for 7 d and was recover ed from the small intestine, cecum, and nasal cavity 2 d following tre atment. Strain AC1100 treatment impacted the small intestinal anaerobe count, OAGNR counts, and reduced lactobacilli numbers. Strain AC1100 also altered the cecal OAGNR and lactobacilli. Therefore, pulmonary tr eatment of mice with Pseudomonas aeruginosa or cepacia affects the bal ance of the protective intestinal microbiota, which may cause further negative health effects (e.g., harbored pathogen multiplication, oppor tunistic pathogen invasion, bacterial translocation).