Our objectives were to develop an ovine model for Escherichia coli-induced preterm delivery, and monitor E. coli (lux modified for photonic detection) invasion of the fetal environment--ewes (124+/-18d of gestation) received intrauterine inoculations using E. coli-lux as follows: control (n = 5), 1.2 x 10(6) CFU/ml (n = 5), 5.6 x 10(6) CFU/ml (n = 5) E. coli-lux. Preterm delivery occurred between 48 and 120 h post-inoculation in 60%, 60% of ewes infected with 1.2, and 5.6 x 10(6) CFU/ml E. coli-lux, respectively, with presence of emitting bacteria confirmed by real-time imaging of lamb tissues. In summary, preterm delivery and/or fetal distress were observed in a majority of inoculated ewes. Finally, the use of photonic bacteria with imaging was a feasible means to monitor bacterial presence ex vivo.