Antimicrobials in the Management of Post-Irradiation Infection
Abstract
Ionizing radiation depresses host defenses and enhances susceptibility to local and systemic infection due to endogenous or exogenous microorganisms. Giving mice a lethal dose of ionizing 60Co-gamma radiation induces a dose-related reduction in the number of both aerobic and anaerobic bacteria from 1010-12 to 104-6 per gram of stool within four days. Although the number of anaerobic bacteria remains low, measured by per gram of stool bacteria increases significantly, up to 109 per gram of stool by the twelfth day following irradiation. This increase is associated with the bacterial translocation of Enterobacteriaceae and fatal bacteremia. Treatment with metronidazole suppressed the anaerobic stool flora and facilitated the increase in the number of Enterobacteriaceae, thus promoting earlier fatal bacteremia. The use of quinolones in the animals was effective in controlling systemic endogenous Gram-negative infection following irradiation. Supplementation with penicillin prevented treatment failures caused by Streptococcus spp. and increased survival. Quinolones given for 21 consecutive days also was effective in managing systemic exogenous infections due to orally ingested Klebsiella pneumoniae and Pseudomonas aeruginosa. The effectiveness of quinolones may be attributed to the inhibition of exogenous microbial growth within the gut lumen while preserving the anaerobic gut flora, and to their systemic antibacterial activity. Based on these findings, the antimicrobial agents recommended for therapy of infection following radiation exposure are ciprofloxacin, levofloxacin, ceftriaxone, cefepime, or gentamicin with or without amoxicillin or vancomycin (to cover gram-positive bacteria), given for 21 days.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2005
- Accession Number
- ADA438718
Entities
People
- G. David Ledney
- I. Brook
- M. O. Shoemaker
- T. B. Elliott
Organizations
- Armed Forces Radiobiology Research Institute