Evaluation of four blood culture systems using parallel culture methods

Commercially prepared Vacutainer thioglycolate broth with SPS (TBSPS), the B-D Vacutainer culture tube with SPS (VCT), the Pfizer E-Vac hypertonic brucella broth with SPS (BBSPS), and our own Trypticase-soy hypertonic broth with SPS (TSBH) were studied by parallel culture methods for their ability to allow the survival of a wide spectrum of organisms, their ability to allow recovery of organisms, and the time required to obtain a recovery from clinical blood cultures. Organisms considered to be clinically significant were recovered from 176 blood cultures. The TSBH system produced all 176 recoveries, the BBSPS system allowed for 170 recoveries, the TBSPS recovered 131, and the VCT accounted for 106 recoveries. The time required to recover any given organism from both the BBSPS and the TSBH systems did not exceed 48 h, whereas 86 of the 131 recoveries from the TBSPS system required more than 72 h and 74 of the 106 VCT recoveries also required more than 72 h. A wide spectrum of organisms were recovered from both the BBSPS and the TSBH systems. The TBSPS system failed to allow the recovery of many streptococci and Pseudomonas spp. and the VCT system failed to recover many organisms.