Quinolone therapy in the prevention of mortality after irradiation.

The effect of oral therapy with three quinolones (ofloxacin, ciprofloxacin, and pefloxacin) in the prevention of postirradiation bacteremia and mortality was tested in B6D2F1 mice given 9.5 Gy 60Co gamma radiation. Only 8 of 60 (13%) untreated mice survived for 30 days, compared to 47 of 60 (78%) mice treated with ofloxacin, 44 of 60 (74%) mice treated with ciprofloxacin, and 42 of 60 (70%) mice treated with pefloxacin (P less than 0.05). The organisms recovered from the mice were Streptococcus spp. and Enterobacteriaceae. More Enterobacteriaceae were recovered from the livers of untreated animals than from the mice treated with the quinolones. However, no reduction in the number of Streptococcus spp. was noted in the animals given quinolones when compared to controls. This study shows that quinolones prolonged survival and decreased systemic spread of Enterobacteriaceae up to 30 days after exposure of mice to lethal irradiation.