Controlled evaluation of 5 versus 10 milliliters of blood cultured in aerobic BacT/Alert blood culture bottles.
Bottles developed for use in the BacT/Alert automated blood culture system (Organon Teknika Corp., Durham, N.C.) can accept up to 10 ml of blood without falling below a 1:5 ratio of blood to broth. We compared the yield and speed of detection of microorganisms in 13,128 adequately filled, paired, aerobic bottles inoculated with 5 versus 10 ml of blood at three university hospitals. A total of 798 microorganisms causing sepsis grew in one or both bottles. The overall recovery of microorganisms from 10-ml samples exceeded that from 5-ml samples (P < 0.001); the increased yield attributed to the additional 5 ml in the samples was 7.2%. The increased yield from 10-ml inocula was most marked for Escherichia coli (P < 0.01) and other members of the family Enterobacteriaceae (P < 0.001). Ten-milliliter samples did not yield more gram-positive bacteria, nonfermentative gram-negative rods, or yeasts. When both bottles were positive, the bottles inoculated with 10 ml of blood showed growth sooner (P < 0.001). Earlier detection with 10-ml inocula was especially notable for coagulase-negative staphylococci (P < 0.001), streptococci (P < 0.001), E. coli (P < 0.025), and other members of the family Enterobacteriaceae (P < 0.025). We conclude that an increase in the volume of blood inoculated into BacT/Alert aerobic blood culture bottles from 5 to 10 ml will increase the overall yield and the speed of detection of clinically important blood pathogens.
Weinstein
M P
MP
Department of Medicine, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick 08901.
Mirrett
S
S
Wilson
M L
ML
Reimer
L G
LG
Reller
L B
LB
D000332:Aerobiosis; D016470:Bacteremia / Q000382:microbiology*; D001419:Bacteria / Q000254:growth & development / Q000302:isolation & purification*; D001431:Bacteriological Techniques / Q000295:instrumentation*; D001769:Blood / Q000382:microbiology*; D004755:Enterobacteriaceae / Q000254:growth & development / Q000302:isolation & purification; D004926:Escherichia coli / Q000254:growth & development / Q000302:isolation & purification; D005069:Evaluation Studies as Topic; D016469:Fungemia / Q000382:microbiology*; D005658:Fungi / Q000254:growth & development / Q000302:isolation & purification*; D006801:Humans; D009172:Mycology / Q000295:instrumentation / Q000379:methods*; D013211:Staphylococcus aureus / Q000254:growth & development / Q000302:isolation & purification