Isolation of Salmonella typhi from standard whole-blood culture vs blood-clot cultures.

The use of 10% oxgall and bile broth medium, both supplemented with freshly prepared 100 u/ml streptokinase, for isolating Salmonella typhi by clot culture technique was evaluated and compared against whole blood culture systems (3 ml blood in 9 ml media and 8 ml blood in 72 ml media). These gave a 1:4 and 1:10 blood to medium ratio, respectively. Clot cultures in 10% oxgall (CLOX) gave a 57% positive isolation rate for S. typhi. A similar result was obtained from clot cultures in bile broth medium (CLBB). A total of 184 samples identified as positive for S. typhi were tested. There was no significant difference between the use of 10% oxgall or bile broth medium when used for clot culture. The whole blood culture systems still showed a significantly better rate of isolation than the clot culture methods.