Antibiotics combined with antigen-based vaccine protects guinea pigs against anthrax.

2003 JAN 8 - (NewsRx.com & NewsRx.net) -- by Maria G. Essig, MS, ELS, senior medical writer - Almost all of the guinea pigs treated with a regimen of antibiotics and a protective-antigen vaccine survived a challenge with a lethal dose of anthrax spores, according to researchers in Israel.

Zeev Altboum and colleagues at the Israel Institute for Biological Research in Ness-Ziona, Israel, exposed guinea pigs intranasally to 75 times the LD[subscript]50 of Vollum anthrax spores or 87 times the LD[subscript]50 of ATCC 6605 spores. Twenty-four hours later, the animals were given 14 days of antibiotic treatment with ciprofloxacin, tetracycline, erythromycin, cefazolin, or trimethoprim-sulfamethoxazole (TMP-SMX).

The animals treated with ciprofloxacin, tetracycline, and erythromycin were protected, but those given cefazolin or TMP-SMX died of the anthrax infection. The protective ability of erythromycin ended when the treatment period ended and all of the erythromycin-treated animals died.

Two of eight Vollum-infected animals and one of the nine ATCC 6605-infected animals given tetracycline survived. Ten of the 14 guinea pigs treated with ciprofloxacin survived after treatment ended, with survival higher in the group of animals that received higher ciprofloxacin doses.

When animals infected with 46 times the LD[subscript]50 of Vollum spores were treated for 30 days with ciprofloxacin or tetracycline, survival rates during the treatment period were 89% (8/9) and 100% (9/9), respectively. However, once treatment ceased, 50% of the surviving ciprofloxacin-treated animals lived and 56% of the tetracycline-treated animals survived.

Survival rates of 88% (7/8) and 100% (8/8) after cessation of treatment were achieved when Vollum-infected ...