A group of 53 normal human plasma samples showed variable staphylococcal anti-delta-hemolysin activity. Albumin and globulin in low concentrations did not interfere with the hemolytic activity of delta lysin. Rabbit and guinea pig sera contained anti-delta lysin in low titer. Staphylococcus aureus 209 produced equal zones of hemolysis when grown on washed erythrocyte agar plates prepared from 16 different human blood samples while whole blood agar plates prepared from the same blood gave variable and smaller zones under similar conditions.
This paper consists of an epidemiological study of 52 cases of Q fever occurring in metropolitan Adelaide in 1957 and also a description of the results of a survey of 516 sera obtained from abattoir workers.The only case occurring outside the abattoirs was a dairy farmer who probably became infected while visiting the abattoirs. If this were so the incubation period (35 days) of his disease would have been exceptionally long.The general features of the outbreak, which lasted several months, differed from those on the North American continent in that the latter occurred explosively within a few days with very high attack rates. The situation in the Adelaide abattoirs is similar to that in Brisbane, where the disease appears to be endemic. However, unlike in Adelaide, cases are commonly recognized outside the abattoirs in Brisbane.In the abattoirs the disease affected mainly inspectors, those working on killing beef, and those working on offal. Mutton workers were not so severely affected. However, all these groups had similar incidences of low titre antibodies suggesting that in the past Q fever spread equally in all killing departments. In departments not directly associated with slaughtering the incidence both of cases in 1957 and low titre antibodies was relatively small.It was suggested that the epidemiological features of Q fever in Adelaide could be explained by the irregular appearance of animals from infected herds situated perhaps in Queensland—a known endemic area. Perhaps the appearance of such animals in the Adelaide abattoirs might be governed by meteorological conditions such that they were prevented from going to the ordinarily most convenient slaughterhouse.
A precise method of assaving viruIence of Sfaphylo~occmis a u r a s for mice by intraperitmml injection with mucin is described; the resuIts indicated that most bacteriophage types of S. aprreus possessed similar virulence, an LDgo consisting of millions of orga~lisms. The variability in results of similar tests by previo~is authors i s thought to reside in the use of techniques allowing excessive variability.The Smith strain of S. alcreus is shown to be exceptionally virulent, requiring only one colony-form in^ unit to kill a mouse. However, the survival time of mice after inoculation with the Smith strain i s longcr than that of other strains giving equivalent mortality. An esplanation is suggested for this latter phenomenon, and the manner in which the Smith strain causes death is considered.
IntroductionThe purpose of the work described in this paper was to inject strains of Staphylococcus aureus into mice in an attempt to obtain a reproducibIe test of virulence. When the work was started, certain bacteriophage types, notably 80/81, seemed to be more frequentlv associated with outbreaks of infection in hospitals OVilliams 1959) and, since no tests comparing the virulence of different bacteriophage types had been reported, we thought it of importance to investigate this. A preliminary review of the Iiterature revealed a
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