Comparison of the Bactec 9240 and BacT/Alert Blood Culture Systems for Evaluation of Placental Cord Blood for Transfusion in Neonates

Abstract

The Bactec 9240 and the BacT/Alert blood culture systems were compared as a means for detection of bacterial contaminants in whole blood, concentrated red cells, and plasma preparations prepared from umbilical cord blood (UCB) samples. Ninety-two UCB units seeded with low levels of various bacteria were evaluated. In more than 50% of cases, growth was not detected in plasma using either system (P < 0.001). When concentrated red cells and whole blood were compared, the Bactec system detected bacterial growth consistently sooner than the BacT/Alert system in all seeded bacteria except Staphylococcus species in whole blood. The median lengths of time to detection (LTD) for whole blood and concentrated cells in BacT/Alert were 18.7 h and 18.5 h, respectively. The median LTD for the same blood fractions using the Bactec system were 16.05 h and 15.64 h. These differences in LTD by blood culture system and sample type were statistically significant (whole blood, P ‫؍‬ 0.0449; concentrated cells, P ‫؍‬ 0.0037). Based on the results of our study, we recommend the use of either concentrated red cells or whole blood for sterility testing in UCB samples. In our laboratory, the Bactec system compared to the BacT/Alert system was the superior method for rapid detection of bacterial contaminants in cord blood.While all neonates experience a decline in their circulating red blood cells immediately after birth, anemia is a more common complication for premature neonates (27,28). Annually in the United States, an estimated 130,000 anemic, critically ill infants receive approximately one million red blood cell transfusions (31). Autologous blood transfusions have been shown to be safe in both adult and pediatric patients (17,21,25). Umbilical/placental cord blood is autologous blood from a neonate (20), and the use of autologous umbilical cord blood (UCB) has long been discussed among neonatologists (5,6,9,10,29). Owing to the increasing utilization of UCB for the transplantation of hematopoietic stem cells, significant progress has been made in developing safer and more efficient collection techniques for UCB (12,14). In neonates, bacterial contamination has been described as the third most common cause of transfusion-related fatality, with most fatalities occurring in gram-negative sepsis (13). Unfortunately, many cases of transfusion-transmitted bacterial infection remain unrecognized and underreported (4, 18, 30). While much experience exists now regarding the efficacy, recovery, and safety of UCB, only few studies investigated the prevalence of bacterial contamination of cord blood. These studies report variable bacterial contamination rates of between 1.85 and 12% (3,7,8,10,14). Bacterial contamination consists predominantly of organisms known as typical skin contaminants similar to those described in adult blood culture collections. Organisms of the vaginal flora have been described as an additional and important component of contaminants in UCB. The American Association of Blood Banks (AABB) standards require that a small ...

Optimization of cord blood unit sterility testing: impact of dilution, analysis delay, and inhibitory substances

“…The present work also underlines the fact that the volume of plasma in the inoculum used for microbial detection should be minimized to ensure the survival of potential contaminating bacteria and to reduce the risk of false‐negative results. Riedel and colleagues have observed that bacterial contamination in spiked CB samples is more readily detected by automated systems when whole blood units or RBCs, rather than CB plasma, are used as inoculum . In addition, Clark and coworkers have demonstrated that screening CB for microbial contamination using the plasma fraction yielded a detection rate of 27%, which is consistent with our results; whereas inocula made with a mixture of plasma, RBCs, and FP led to a detection rate that reached 71% .…”

Is There a Role for Autologous/Placental Red Blood Cell Transfusions in the Anemia of Prematurity?

“…However, even in reports after 2000, bacterial contamination was detected in up to 13% of units (22-25). Thus, it is critically important to carefully consider the threat of bacterial contamination whenever transfusing placental blood/RBCs and to take appropriate steps for appropriate case selection and for quality assurance/control (e.g., surveillance cultures of collected units) (26). …”

Implementation of Bacterial Detection Methods into Blood Donor Screening – Overview of Different Technologies

“…If platelet concentrates were already transfused, physicians took special care of their patients due to suspected bacterial infection. Additional culture systems, such as the Bactec™ system (BD Diagnostics -Diagnostic Systems, Becton Dickinson GmbH, Heidelberg, Germany), were also available on the market and were implemented in some of the blood donor services with comparable data [19][20][21]. The Pall eBDS system [19,[22][23][24] (Pall GmbH, Dreieich, Germany) must be grouped between the culture methods and the rapid detection methods.…”