title: Is 60 days of ciprofloxacin administration necessary for postexposure prophylaxis for Bacillus anthracis?
abstract: Sixty days of ciprofloxacin administration at 500 mg every 12 h is currently recommended for the prophylaxis of inhalational exposure to Bacillus anthracis. We examined Bacillus anthracis (Delta-Sterne strain) in our hollow-fiber infection model. We measured the ciprofloxacin concentrations achieved and the number of organisms present before heat shock (total population) and after heat shock (spore population). We fit a mathematical model to these data. Monte Carlo simulation with differing initial spore burdens (3, 5, and 6.9 log(10) CFU/ml) demonstrated that 35 days of this regimen would completely clear the spore burden in 95% of patients. Durations of 110 days did not achieve 99.9% eradication, irrespective of initial burden, because of between-patient variance in drug pharmacokinetics. Given the absence of person-to-person transmission for Bacillus anthracis, adverse drug effects with long-term ciprofloxacin administration, and the possibility of engendering resistance in bodily flora, shorter prophylaxis duration should be given consideration, along with careful monitoring of all exposed individuals.
authors: Ordway Research Institute, Albany, New York 12208, USA. Gdrusano@ordwayresearch.org
authors: G L
authors: GL
authors: Drusano
authors: Olanrewaju O
authors: OO
authors: Okusanya
authors: Adedoyin
authors: A
authors: Okusanya
authors: Brian
authors: B
authors: Van Scoy
authors: D L
authors: DL
authors: Brown
authors: Robert
authors: R
authors: Kulawy
authors: Fritz
authors: F
authors: Sörgel
authors: Henry S
authors: HS
authors: Heine
authors: Arnold
authors: A
authors: Louie
mesh_terms: D000881:Anthrax / Q000382:microbiology / Q000517:prevention & control* / Q000635:transmission; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D001408:Bacillus anthracis / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D002939:Ciprofloxacin / Q000008:administration & dosage*; D015169:Colony Count, Microbial; D004334:Drug Administration Schedule; D024881:Drug Resistance, Bacterial / Q000235:genetics; D018869:Heat-Shock Response; D006801:Humans; D008954:Models, Biological; D015233:Models, Statistical; D009010:Monte Carlo Method; D009154:Mutation; D013171:Spores, Bacterial / Q000187:drug effects; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D002939:Ciprofloxacin