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A total of 640 blood specimens from patients in an area endemic for enteric fever were cultured in parallel in tryptic soy broth with and without sodium polyanethanol sulfonate (SPS). A total of 95 specimens were positive for Salmonella spp., 54 for Salmonella typhi, and 41 for Salmonella paratyphi A in one or both bottles of a set. Significantly higher rates of recovery were obtained from the SPS-containing medium (P less than 0.01) upon subculturing blindly at 24 h and 3 days of incubation. Subcultures performed at 7, 14, and 21 days also yielded a greater number of positive cultures with SPS than without it, although the differences between the two media were not significant (P greater than 0.05). Neither of the media yielded 100% of the positive cultures. Moreover, even if the results of the two media were combined, 34 and 19% of the isolates would have been missed if the specimens had not been incubated to 14 and 21 days, respectively. The data indicate that SPS aids in early recovery of S. typhi and S. paratyphi A from blood cultures, and additionally, that under the conditions used in the study, incubation beyond a 1-week period is required for efficient isolation of these organisms from blood.

Eight hundred blood cultures were tested in parallel in three conventional systems: tryptic soy broth containing 0.05% sodium polyanethosulfonate (TSB-SPS), whole blood in bile (BILE-BLOOD), and blood clots in bile (BILE-CLOT). Sixty-eight cultures were Salmonella typhi positive and 29 were positive for S. paratyphi A in at least one of the systems. Analysis of the isolation rates of the 97 Salmonella-positive specimens showed that BILE-BLOOD was significantly more sensitive (p less than 0.05) than either TSB-SPS or BILE-CLOTS, and that the latter two were not significantly different. The time required for positive results was shortest in BLOOD-BILE which was significantly quicker than BILE-CLOTs (p less than 0.05), but not TSB-SPS (p greater than 0.05). Possible explanations for the observed, superior performance of the BILE-BLOOD system are discussed and recommendations for efficient recovery of enteric fever salmonellae from blood are presented.