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Updated: Jul 14, 2026
Microtiter Dish Biofilm Formation Assay
Published on: January 30, 2011
Staphylococcus epidermidis forms biofilms under simulated platelet storage conditions
Carey Greco1, Irene Martincic, Arjeta Gusinjac
1Canadian Blood Services, Ottawa, Ontario, Canada.
Background:
Staphylococcus epidermidis grows slowly in platelet (PLT) preparations compared to other bacteria, presenting the possibility of missed detection by routine screening. S. epidermidis is a leading cause of nosocomial sepsis, with virulence residing in its ability to establish chronic infections through production of slime layers, or biofilms, on biomedical devices. This study aims to establish biofilm formation (BF) as a mode of growth by S. epidermidis in PLT preparations.
Study Design And Methods:
Biofilm-positive (BFpos) and -negative (BFneg) S. epidermidis strains were grown in whole blood-derived PLTs (WBDPs) and in glucose-rich medium (TSBg). An assay for BF was adapted for cultures grown in WBDPs or filtered WBDPs in polystyrene culture plates. Bacterial attachment to polyvinylchloride PLT bags and PLTs was examined by scanning electron microscopy.
Results:
Both strains display similar growth profiles in WBDPs and TSBg. Unexpectedly, evidence of BF was observed on PLT bags and on PLTs directly, not only by the BFpos strain but also by the BFneg strain. The BFpos strain displayed greater plastic adherence than the BFneg strain in WBDPs (p < 0.05). BF by the BFneg strain was approximately 10-fold greater in WBDPs compared to TSBg (p < 0.05), likely by use of PLTs as a scaffold. Furthermore, BF by S. epidermidis was significantly decreased when PLT concentration was reduced 1000-fold.
Conclusions:
S. epidermidis forms biofilms on PLT aggregates and on PLT bags under PLT storage conditions. Our results demonstrate that the PLT storage environment can promote a BF growth mechanism for contaminant bacteria.
Insights
Staphylococcus epidermidis can form biofilms in platelet preparations, potentially leading to missed detection. Platelets act as a scaffold, promoting bacterial biofilm formation in storage conditions.
Area of Science:
- Microbiology
- Hematology
- Infectious Diseases
Background:
- Staphylococcus epidermidis exhibits slow growth in platelet preparations, risking detection failure.
- This bacterium is a primary cause of nosocomial sepsis, known for forming biofilms on medical devices.
Purpose of the Study:
- To investigate biofilm formation (BF) by Staphylococcus epidermidis within platelet (PLT) preparations.
- To determine if PLT storage conditions promote bacterial biofilm development.
Main Methods:
- Cultured biofilm-positive and -negative S. epidermidis strains in whole blood-derived PLTs (WBDPs) and TSBg.
- Adapted a BF assay for WBDP cultures and examined bacterial attachment via scanning electron microscopy.
Main Results:
- Both S. epidermidis strains showed similar growth in WBDPs and TSBg.
- Biofilm formation was observed on PLT bags and PLTs by both strains, with the BFneg strain showing increased BF in WBDPs.
- Reduced PLT concentration significantly decreased S. epidermidis biofilm formation.
Conclusions:
- Staphylococcus epidermidis forms biofilms on platelet aggregates and storage bags under typical PLT storage conditions.
- The PLT storage environment facilitates biofilm formation in contaminating bacteria.
