Volume of blood submitted for culture from neonates

Abstract

We prospectively examined 298 sets (298 aerobic, 299 anaerobic, and 73 resin cultures) of blood cultures from 161 critically ill newborns. The attending physicians were unaware of the study. The mean blood volume per patient (aerobic and anaerobic) was 1.05 (range, 0.11 to 3.04) ml. The mean blood volume per aerobic bottle was 0.53 (range, 0.01 to 1.90) ml. Among aerobic samples 2.7% were .0.1 ml, 16% were s0.3 ml, 33% were s0.4 ml, and 55% were s0.5 ml. For anaerobic cultures the mean blood volume was 0.52 (range, 0.01 to 1.79) ml. Among anaerobic samples 2.7% were s0.1 ml, 15% were s0.3 ml, 35% were .0.4 ml, and 58% were .0.5 ml. Blood volume did not correlate with gestational age, chronologic age, or weight. The mean volume of blood submitted in positive cultures was not significantly greater than that in negative cultures. The blood volume used for culture from ill newborns may be inadequate for detecting sepsis, and the adequacy of currently available culture methods needs to be assessed for the small samples submitted from critically ill newborns.

New Approaches to Preventing, Diagnosing, and Treating Neonatal Sepsis

“…However, identification of pathogenic organisms in neonates with sepsis syndrome is fraught with difficulties. Bacterial load may be low due to mothers receiving antepartum or intrapartum antibiotics and because only small amounts of blood can often be taken from newborns [53]. Contamination rates may also be very high due to the technical difficulties of sterile venipuncture in small babies.…”

“…Automated blood culture systems have long been considered the gold standard for microbiological diagnosis. However, despite improvements in growth media and instrumentation, results of blood culture can be delayed by up to 48 hours [53,55]. The condition of a neonate with true sepsis can deteriorate quickly, thus the most common approach is to initiate empiric broad-spectrum antibiotic therapy in all young infants with suspected bacterial infection [49].…”

Incubation time required for neonatal blood cultures to become positive

“…5 Positive results can be influenced by a number of factors including: collection technique, volume of blood drawn, number of colony-forming units present in the blood at the time of collection and the use of intrapartum antibiotics. [5][6][7] Most infants who have a blood culture collected are commenced on antibiotics while results are awaited. Our current practice is to treat the infant with intravenous antibiotics for a minimum 48 h after the blood culture has been collected.…”

Frequency of Low-Level Bacteremia in Children from Birth to Fifteen Years of Age

“…Previous studies which have based a diagnosis on a single small-volume blood culture have underestimated the prevalence of bacteremia in children (15). Blood volumes traditionally used for cultures for infants and older children are frequently inadequate for the comprehensive and rapid detection of pathogens which may be present in relatively low concentrations in the blood (15,17,24,30). As little as 1 ml of blood has been routinely cultured for pediatric patients (8), and a recent report suggests that 0.2 ml of blood provided 95% sensitivity, compared to 2 ml of blood, for infants from birth to 12 months of age (32).…”

“…Reasons for culturing small volumes of blood from pediatric patients have included concern about the small blood volumes of younger patients (11,13,21,30,31), difficulties frequently encountered in obtaining blood from children (15,30), desires both to avoid the need for blood transfusions after repeated phlebotomies (24,30,31,39) and to start antibiotics without delay (10)(11)(12)(13)39), and the common belief throughout the 1990s that bacterial concentrations are often greater ("far greater" [32]) in the blood of younger patients than in that of adults (26,28,39,40). However, the advantages of culturing larger volumes of blood from children and inoculating two or more culture devices (bottles and/or Isolators) include an increase in the number of children from whom pathogens are detected (8,9,15,17,24,30,35,39), a decrease in detection times (15,35), an improved ability to differentiate pathogens from contaminants (1,5,25,34,37,39), assistance either with the selection of more specific antimicrobial agents when a pathogen is detected and identified or with the discontinuation of unnecessary therapy when a sensitive blood culture system remains negative for pathogens (2,6,…”