Routine evaluation of the nonradiometric BACTEC NR 660 system

The present study compares the sensitivity, accuracy, and practicability of a nonradiometric blood culture system with those of the standard blood culture system in use in our laboratory. A total of 1,080 sets of four blood cultures bottles were compared, giving 143 positive aerobic-medium associations and 139 positive anaerobic-medium associations. The conventional system recovered 171 isolates, whereas the BACTEC NR 660 system (Johnston Laboratories, Towson, Md.) recovered 155 isolated. There were no significant differences in total isolates with either system (P more than 0.05). The BACTEC NR 660 system recovered a slightly lower number of Serratia marcescens and Streptococcus faecalis but a higher number of Pneumococcus spp. The mean detection times were 55.9 h with the conventional system and 31.6 h with the BACTEC NR 660 system (P less than 0.001). Our results demonstrate that the BACTEC NR 660 system is suitable for routine use.