Improved detection of Cryptococcus neoformans in the BACTEC NR 660 blood culture system

To determine the impact of continuous agitation versus 24 hours agitation on the growth of Cryptococcus neoformans in the BACTEC NR 660 blood culture system, the authors compared recovery and detection time for 50 clinical isolates in Peds Plus, 26 Plus, and Fungal Medium bottles in paired simulated blood cultures. After 144 hours of continuous agitation, the Peds Plus bottle detected 96% of the isolates in an average of 82.5 hours, the 26 Plus bottle detected 96% in 79.5 hours, and the Fungal Medium detected 98% in 81.8 hours. For the bottles that were agitated only for the first 24 hours and incubated motionless for 120 hours (as recommended by the manufacturer), the Fungal Medium detected 82% of the isolates in 100.7 hours. However, the Peds Plus and 26 Plus bottles each detected only 38% of the isolates in an average of 112.4 hours and 109.9 hours, respectively. These results indicate that continuous agitation of BACTEC blood culture bottles for the full incubation time significantly improves (P < or = .0001) the detection and recovery of C neoformans.