Lack of Mammalian Pathogenicity of Entomocidal Isolates of Bacillus sphaericus

Abstract

Bacillus sphaericus strains SSII-1, 1404-9, and 1593-4 were tested for mammalian pathogenicity and infectivity. Mice, rats, and rabbits were injected by various routes including intracerebral, intraocular, subcutaneous and intraperitoneal in order to maximize the opportunity for the bacteria to behave as mammalian pathogens. High doses of viable or autoclaved bacteria injected intracerebrally, intraocularly or subcutaneously produced mild lesions near the injection sites. No animals died and there were no disseminated lesions. Bacteria could be recovered 2 wk after intracerebral injection but quantitative recovery studies showed a precipitous decline in recoverable organisms by 5 days after injection. About 10 organisms/lOOmg of brain persisted for another 8–10 days after which the brains were sterile. The data show that all B. sphaericus strains tested were avirulent for the mammals tested. It is concluded that these organisms are highly unlikely to be hazardous for man.