Development of infection with Streptococcus bovis and Aspergillus sp. in irradiated mice after glycopeptide therapy

The use of ofloxacin and glycopeptides was evaluated for the treatment of infections arising in C3H/HeN female mice irradiated with 8.3 Gy from a 60Co source. The 21 day regimen began 72 h after irradiation when each of five sets of experimental animals received three antimicrobial therapy regimens and a saline-treated control group. With 40 mice in each group, 20 were used to monitor survival, 20 for the recovery of bacteria from the liver culture. Treatment groups were oral ofloxacin 20 mg/kg/day; oral or intramuscular vancomycin 50 mg/kg/day; oral teicoplanin 50 mg/kg/day; ofloxacin and vancomycin; ofloxacin and teicoplanin; or saline. Bacteria recovered from saline treated mice were Enterobacteriaceae and Streptococcus spp. By comparison, fewer Enterobacteriaceae were isolated from ofloxacin treated mice and fewer Streptococcus spp. in both vancomycin and teicoplanin treated mice. However, glycopeptide-treated mice developed infection with Aspergillus fumigatus and glycopeptide resistant Streptococcus bovis. Mortality rates within 60 days of irradiation were 100% in all treatment and control groups with the exception of ofloxacin which was 25%-35%. These data suggest that glycopeptide therapy increases rates of systemic infection with fungi and antibiotic resistant bacteria in irradiated mice.