Survival of Environmental Microbial Agents in CD-1 Mice Following Oral Exposure

Abstract

Microbial agents have many applications in the environment and are replacing chemicals and engineering processes due to improved efficacy, reduced toxicity, and less cost. Typically, innocuous species are used, however, unless the products include genetically engineered microorganisms, potential health effects are not scrutinized. In order to investigate possible health concerns, four surrogate microbial agents were studied in 6i6o and in 6itro. Male CD-1 mice were treated perorally (p.o.) with average doses of 2.62 × 10 8 colony forming units (CFU) of Pseudomonas aureofaciens, 1.16 × 10 8 CFU of Burkholderia cepacia, 1.78× 10 8 CFU of P. fluorescens, or 1.86 ×10 8 CFU of P. putida. To determine clearance of the dosed strains from mice, lungs, intestinal tract (small, large, cecum), mesenteric lymph nodes (MLN), spleen, and liver were homogenized individually, and dilutions inoculated onto selective media for enumeration of intestinal populations. All strains were recovered in the intestinal tract 3 hours after treatment but P. fluorescens and P. aureofaciens were cleared after the first day. P. putida and B. cepacia survived for at least 2 days in the large intestine and B. cepacia was detected in the small intestine 7 days after treatment. P. aureofaciens and B. cepacia were isolated from the lungs for 2 and 7 days. All strains translocated to the MLN and were detected 3 hours after treatment. B. cepacia was isolated from the spleen and liver 3 hours post-treatment. P. aureofaciens and P. putida translocated to the liver within 3 hours of treatment and P. fluorescens translocated to the spleen. None of the dosed strains were detected extraintestinally after 3 hours. All strains were eliminated from in 6itro intestinal continuous cultures. The models described in this study facilitate the identification of potential human safety issues associated with biotechnology agents.