The fate of S. typhi in blood clot in relation to the problem of isolation.

Bile salt broth containing streptokinase (100 units/ml.) has in our experience proved superior to ordinary bile broth as a culture medium for the isolation of S. typhi from blood clot (Thomas, Watson, and Hewstone, 1954). This superiority refers both to the total number of positive isolations and to the shorter duration of incubation required. In a series of 18 cases (16 typhoid and two paratyphoid A), where one half of each clot was incubated in 15 ml. of streptokinase'broth and the other half in 15 ml. of bile broth alone, six of the latter were negative after 14 days' incubation, but the corresponding halves in streptokinase broth produced a growth of S. typhi. In view of the failure of these six half-clots to produce a positive result a study was undertaken of the fate of S. typhi in blood clot.