Multicenter comparison of the high volume (10 ml) NR BACTEC PLUS system and the standard (5 ml) NR BACTEC system

Abstract

This multicenter study was designed to compare the new BACTEC PLUS system (nonradiometric), which utilizes an 8- to 10-ml blood inoculum in a resin-containing medium, to the standard BACTEC (nonradiometric) without resins and 5-ml blood inoculum. There were 12,341 compliant sets studied, yielding 1331 positives, with 1099 sets deemed clinically significant. Overall the BACTEC PLUS showed an enhanced recovery of 33% (p less than 0.001) over its standard counterpart, with significant yield increased in the staphylococci (p less than 0.001), streptococci (p less than 0.002), pseudomonads (p less than 0.002), Enterobacteriaceae (p less than 0.001), and other aerobic Gram negatives (p less than 0.02). The enhanced performance increased to 53% if the patient was receiving any antibiotics at the time the blood was cultured. In patients known to be free of antibiotics at the time of blood draw, there was still an increased yield of 18%. The new system detected positivity at least one reading sooner than twice as often as the converse, and confirmed septic episodes significantly more often (21% overall) (41% on antibiotics) (15% no antibiotics). The BACTEC PLUS has distinct advantages over its low blood volume, nonresin counterpart.