Studies on Dissociation of Certain Paratyphoid Bacilli

Abstract

In the course of certain bacteriophage studies, cells, thought to be a type of variant, have been found which have the ability to precipitate calcium sulphite. The technique employed and the detailed results, together with a review of the literature, will appear in a forthcoming publication. Since these presumable variants gave rise to a daughter-colony-like structure, within which sulphite crystals were incorporated, they may be termed thiosomes. These sulphite-containing bodies have apparently not been reported previously nor has microchemical technique been resorted to in studies of this type.

On “Bacto-” agar plates, typical thiosomes are small (0.005-0.015 mm.), opaque bodies which are superimposed upon and at times in the medium surrounding ordinary colonies. They are black by transmitted light, white by reflected light, show extinction with crossed nicols and are iridescent with polarized light. Microchemical technique employed for the detection of cations and anions present revealed crystals typical of Ca⁺⁺ and SO₃ ^–. Thiosomes were originally observed associated with Salmonella schottmülleri colonies obtained from sealed filtrates which had become opalescent or slightly cloudy; from certain daily broth transfers, when no filtrations intervened, of Escherichia coli, Eberthella typhi, Salmonella paratyphi, Salmonella schottmülleri and Salmonella paratyphi, Type C; and in association with an atypical strain of E. coli obtained from a case of cervicitis. Under proper experimental conditions, thiosomes were produced at will from the above named cultures. Atypical thiosomes, which more closely simulated daughter-colony-like structures and which were devoid of blackness, were not polarized and never occurred outside the colonies, were found upon a synthetic medium and also upon ordinary fresh veal infusion agar plates. Media used contained several concentrations of NaCl and CaCl₂ and mammalian Ringer's; media to which no salts were added were also used.