Comparative study of three blood culture systems for isolation of enteric fever Salmonella.

ABSTRACT

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.