Authors : Nayana Thankam Binu, Nayana Thankam Binu, Anitha G, Anitha G, Deepashree , Deepashree , Subhashree Samantaray, Subhashree Samantaray, Apurba Sankar Sastry, Apurba Sankar Sastry
DOI : 10.18231/j.ijmmtd.2019.040
Volume : 5
Issue : 4
Year : 2019
Page No : 176-180
Aim: To determine the appropriateness of blood volume in automated blood culture bottles of the
BACT/ALERT 3D system, its effect on isolation rate and time to positivity of pathogens.
Materials and Methods: The study was carried out in a tertiary care hospital in South India from 1st
March 2018 to 31st August 2018. Automated blood culture bottles sent to Microbiology laboratory for
blood culture were included in the study. The bottles were weighted by electronic weighing balance.
The filled blood culture bottles received at microbiology laboratory were re-weighed and was categorized
into appropriately filled and inappropriately filled bottles. Frequency of appropriately filled bottles and
inappropriately filled bottles was expressed in percentage.
Result: A total of 8740 blood culture bottles were included in the study, out of which the blood volume was
found to be suboptimum in 3978 bottles (45.5%), optimum in 3498 bottles (40%) and overfilled in 1264
bottles (14.5%). There was an increase in the number of blood culture bottles with optimum blood volume
from 35.1% in March to 58.12% in August. The average TTP for true pathogens was found to be 16.72
hrs. with optimum blood volume, 17 hrs. with overfilled blood volume and 21.5 hrs. with sub-optimum
blood volume. The isolation rate for true pathogens was found to be 88.62% with optimum blood volume,
86.43% with overfilled blood volume and 70.01% with sub-optimum. The false positive rate was found to
be 4.1% with overfilled blood volume, 1.6%with sub-optimum and 1.4%with optimum blood volume.
Conclusion: Through this study, the correlation between the blood volume with the isolation rate, time to
positivity and false positivity of blood culture isolates was established.
Keywords: Blood culture, Blood volume, BACT/ALERT 3D, Time to positivity, Isolation rate.