Transfusion risk reduction: Testing for bacteria

Implementation of helicase-dependent amplification with SYBR Green I for prompt naked-eye detection of bacterial contaminants in platelet products

Platelet transfusions may lead to more significant risks of infection and septic transfusion reactions that can be fatal to the recipient. Platelet products should be screened to limit or detect bacterial contamination before application to patients to minimise any adverse reactions. This study aimed to develop a helicase-dependent amplification (HDA) technique targeting a universal highly conserved bacterial gene, 16S rRNA, in combination with naked-eye detection using SYBR Green I (HDA/SYBR Green I) to detect bacterial contamination in platelet products. Thirty positive samples were obtained from spiked platelet products by five transfusion-relevant bacterial strains and were screened for bacterial contamination by HDA/SYBR Green I. HDA/SYBR Green I showed an enhanced yield of bacterial contaminant detection when performed with medium to late shelf life, Day 2 of storage or later platelet products (98.67% sensitivity and 100% specificity compared to the BACT/ALERT culture system). The limit of detection of HDA/SYBR Green I was 1 ng, and there was no cross-reaction with other organisms that could likely contaminate platelet products. The developed HDA/SYBR Green I assay is rapid and simplistic and only requires an easy-to-find heat box, available in general blood bank laboratories, for the amplification step. This technique is suitable for further development as an alternative method to detect bacterial contamination in platelet products in the near future.

Development of Antifouling and Bactericidal Coatings for Platelet Storage Bags Using Dopamine Chemistry

Platelets have a limited shelf life, due to the risk of bacterial contamination and platelet quality loss. Most platelet storage bags are made of a mixture of polyvinyl chloride with a plasticizer, denoted as pPVC. To improve biocompatibility of pPVC with platelets and to inhibit bacterial biofilm formation, an antifouling polymer coating is developed using mussel-inspired chemistry. A copolymer of N,N-dimethylacrylamide and N-(3-aminopropyl)methacrylamide hydrochloride is synthesized and coupled with catechol groups, named DA51-cat. Under mild aqueous conditions, pPVC is first equilibrated with an anchoring polydopamine layer, followed by a DA51-cat layer. Measurements show this coating decreases fibrinogen adsorption to 5% of the control surfaces. One-step coating with DA51-cat does not coat pPVC efficiently although it is sufficient for coating silicon wafers and gold substrates. The dual layer coating on platelet bags resists bacterial biofilm formation and considerably decreases platelet adhesion. A cationic antimicrobial peptide, E6, is conjugated to DA51-cat then coated on silicon wafers and introduces bactericidal activity to these surfaces. Time-of-flight second ion-mass spectroscopy is successfully applied to characterize these surfaces. pPVC is widely used in medical devices; this method provides an approach to controlling biofouling and bacterial growth on it without elaborate surface modification procedures.