Studies on the susceptibility of Rickettsia burneti to chemical disinfectants, and on techniques for detecting small numbers of viable organisms

Abstract

Preliminary studies showed that, with single passage, guinea pigs, mice, and fertile hens'' eggs had similar susceptibility to small nos. of organisms. However, when repeated passage was made in eggs from apparently uninfected eggs which had received small inocula, rickettsia could be recovered. The use of eggs with subpassage from apparently normal eggs was, there fore, the method used in evaluating the action of disinfectants against the Henzerling strain of R. burnetii. Phenol, ether, Cetavlon, formalin, Dettol and Lysol were studied. Of these materials, 1% Lysol was the most active and destroyed infectivity in 3 hrs. at 37[degree]C. Phenol was the least active; a 0.5% soln. had no effect. Survival times were prolonged by treatment of rickettsia with Cetavlon; Dettol and formalin, but complete kill was not achieved. Increased temp. increased the disinfectant action. Rickettsia were recovered from all 2d subpassage eggs after overnight treatment of the original inoculum with ether; therefore a few organisms must have survived exposure. Misplaced reliance on phenol to destroy rickettsia in vaccine lymph is discussed.