COLONIZATION AND CLEARANCE OF ENVIRONMENTAL MICROBIAL AGENTS UPON INTRANASAL EXPOSURE OF STRAIN C3H/HeJ MICE

Abstract

Environmental dissemination of biotechnology agents is becoming a common practice. Most applications use historically innocuous species; however, potential health effects of individual products are not scrutinized unless they contain genetically engineered microorganisms. In order to investigate possible health concerns, four surrogate microbial agents were studied in vivo. Male C3H/ HeJ (endotoxin-resistant) mice were administered intranasally (i.n.) with ~107 Pseudomonas aureofaciens, Burkholderia cepacia, P. fluorescens, or P. putida. To determine clearance of the dosed bacterial strains, lungs, small intestine, large intestine, cecum, mesenteric lymph nodes ( MLN) , spleen, and liver were homogenized individually, plated, and dilutions inoculated onto selective media. Pseudomonas fluorescens and P. putida were eliminated from the lungs by 2 d posttreatment, and P. aureofaciens was not detected in the lungs by 5 d posttreatment. Burkholderia cepacia was reisolated from the lungs and cecum for the experimental duration (14 d). Translocation to extraintestinal sites (MLN, spleen, and liver) also occurred. Burkholderia cepacia was recovered from the MLN for 10 d after treatment of mice. Pulmonary exposure to several bacterial strains resulted in unexpected mortality. Pseudomonas aureofaciens was lethal at the lowest dose (8.26 x 106 CFU/ mouse) , while P. fluorescens and B. cepacia were fatal at higher doses ( 6.15 x 108 CFU/mouse and 1.34 x 108 CFU/mouse, respectively). By using the model described in this study, human safety issues can be more easily addressed and evaluated.