Non‐transferrin‐bound iron in platelet concentrates promotes the growth of Staphylococcus epidermidis

Abstract

PCs stored in plasma or AS contain a low level of NTBI because of the displacement of iron from plasma-derived transferrin by citrate. NTBI in the PC medium supports the growth of S. epidermidis.

Bicarbonate inhibits the growth of Staphylococcus epidermidis in platelet concentrates by lowering the level of non‐transferrin‐bound iron

“…Coagulase‐negative staphylococci do not grow in normal serum unless there is excess iron added 10 and the growth of Staphylococcus epidermidis in the presence of transferrin is critically dependent on NTBI 11,12 . In the previous study, we showed that NTBI in the PC medium promotes the growth of S. epidermidis and that the growth was inhibited by binding of NTBI with deferoxamine 7 …”

“…Less is known about the influence of the endogenous and exogenous constituents of the PC medium on bacterial growth. We have recently shown that PCs stored in plasma or additive solution (AS) contain non‐transferrin‐bound iron (NTBI) owing to the displacement of iron from plasma‐derived transferrin by citrate 7 . Transferrin is known to inhibit the growth of several opportunistic pathogens by keeping iron inaccessible to microorganisms 8,9 .…”

“…We have recently shown that PCs stored in plasma or additive solution (AS) contain non-transferrin-bound iron (NTBI) owing to the displacement of iron from plasma-derived transferrin by citrate. 7 Transferrin is known to inhibit the growth of several opportunistic pathogens by keeping iron inaccessible to microorgan-B isms. 8,9 Coagulase-negative staphylococci do not grow in normal serum unless there is excess iron added 10 and the growth of Staphylococcus epidermidis in the presence of transferrin is critically dependent on NTBI.…”

pH value promotes growth of Staphylococcus epidermidis in platelet concentrates

“…Therefore, the most common organisms involved in bacterial contamination of PCs are part of the normal skin flora that gain access to the PC unit during the collection process. Coagulase‐negative staphylococci (CoNS), especially Staphylococcus epidermidis, are documented to be the most commonly detected bacteria in routine sterility testing of blood components 20,21,23 . Although preliminary results from the US Bacterial Contamination of Blood (BaCon) study suggest that Gram‐negative organisms are the major cause of clinically significant septic reactions, at least 10 cases of severe sepsis due to S. epidermidis contamination of PLTs have been reported in the literature 21,24,25 .…”

“…Although preliminary results from the US Bacterial Contamination of Blood (BaCon) study suggest that Gram‐negative organisms are the major cause of clinically significant septic reactions, at least 10 cases of severe sepsis due to S. epidermidis contamination of PLTs have been reported in the literature 21,24,25 . S. epidermidis is well documented as a human‐opportunistic pathogen and capable of causing severe infections in neutropenic patients 23 . Pathogenesis of S. epidermidis infections mostly relies on adherence to polymer surfaces due to the formation of surface‐attached cellular agglomerations, called biofilms.…”