What is bacterial contamination

Abstract

Placental blood can be used, among other things, for the autologous transfusion of premature babies. The contamination of placental blood is an important limiting factor for clinical use. In this study, the contamination rate of placental bleeding was investigated, with the contamination being determined separately for both vaginal and cesarean births. Furthermore, it should be found out whether there is a blood fraction that is most sensitive for the detection of contamination and whether all contaminations are recorded by a microbiological examination on day 1. In 117 births (89 vaginal births, 28 caesarean sections), the placental blood was obtained in utero by puncturing the umbilical vein after the umbilical cord had been severed with the placenta. The Cord Blood Set MXT 2206DC from Maco Pharma International GmbH was used for this. After centrifugation, the whole blood was separated into the components erythrocyte concentrate, buffy coat and plasma using the Müller-Krüssel system. These three fractions were examined for aerobic and anaerobic bacterial contamination on three days (1, 3, 35), with the whole blood also being examined on day 1. For this purpose, culture bottles were inoculated with 3 ml of the appropriate fraction each and monitored with the Bactec device for seven days at 35 ° C. A total contamination of 28.2% (33/117) was found, whereby vaginal births were contaminated by 33.7% and cesarean sections were contaminated by 10.7%. On the first day of the investigation, 28 contaminations could be recorded. The remaining five contaminations were only detected on control day 3. The Buffy coat differs significantly from the other fractions in terms of contamination detection. 63.6% of the total contamination could be recorded in it. The bacteria detected were germs of the normal skin flora and the vaginal or perineal region, with coagulase-negative staphylococci occurring most frequently. In addition, when comparing the contamination frequencies of the individual classes in this study, a practice effect could be determined. The partly recorded inflammation parameters did not allow any reliable conclusions to be drawn about possible contamination of the placental blood samples. The average volume of placental blood withdrawn was approx. 60 ml. The total contamination of 28.8% is high compared to other studies. This can partly be explained by the fact that in this study the detection possibilities were better exhausted through several examinations (day 1, 3, 35) and through the individually examined blood fractions. As this study shows, when using the Bactec system, not all contaminations could be recorded in just one examination. The results also show that the highest detection rate was achieved in the buffy coat. It is therefore best to always examine the end product used for bacterial contamination and, if possible, also to examine the buffy coat. When taking placental blood, at least the red cell concentrate should always be examined. It is also advisable to use a specially trained collection team to collect placental blood in order to reduce the contamination rate to a minimum.