Determination of the optimum incubation period of blood culture broths for the detection of clinically significant septicemia

Abstract

The value of incubating blood culture broths for more than 7 days was analyzed. A total of 20,155 blood cultures, consisting of a vented Roche tryptic soy broth (R-TSB) bottle and an unvented Difco thiol broth bottle, was processed; 2,509 organisms were recovered in the R-TSB bottles, and 1,865 organisms in the thiol bottles. Only 32 organisms isolated in the R-TSB bottles and 10 organisms isolated in the thiol bottles were detected after incubation for more than 7 days; 15 of the 32 isolates in the R-TSB bottles and all 10 of the isolates in the thiol bottles were either recovered in blood cultures or were not considered to be clinically significant. Thus, incubation of the R-TSB bottles and unvented thiol bottles for more than 7 days is unnecessary for the detection of most clinically significant septicemias.