title: Characterization of the growth dynamics and biofilm formation of Staphylococcus epidermidis strains isolated from contaminated platelet units.
abstract: Bacterial contamination of platelet concentrates (PCs) poses the highest transfusion-associated infectious risk, with Staphylococcus epidermidis being a predominant contaminant. Herein, the growth dynamics of 20 S. epidermidis strains in PCs and regular media were characterized. Strains were categorized as fast (short lag phase) or slow (long lag phase) growers in PCs. All strains were evaluated for the presence of the biofilm-associated icaAD genes by PCR, their capability to produce extracellular polysaccharide (slime) on Congo red agar plates and their ability to form surface-attached aggregates (biofilms) in glucose-supplemented trypticase soy broth (TSBg) using a crystal violet staining assay. A subset of four strains (two slow growers and two fast growers) was further examined for the ability for biofilm formation in PCs. Two of these strains carried the icAD genes, formed slime and produced biofilms in TSBg and PCs, while the other two strains, which did not carry icaAD, did not produce slime or form biofilms in TSBg. Although the two ica-negative slime-negative strains did not form biofilms in media, they displayed a biofilm-positive phenotype in PCs. Although all four strains formed biofilms in PCs, the two slow growers formed significantly more biofilms than the fast growers. Furthermore, growth experiments of the two ica-positive strains in plasma-conditioned platelet bags containing TSBg revealed that a slow grower isolate was more likely to escape culture-based screening than a fast grower strain. Therefore, this study provides novel evidence that links S. epidermidis biofilm formation with slow growth in PCs and suggests that slow-growing biofilm-positive S. epidermidis would be more likely to be missed with automate culture.
authors.affiliation: Canadian Blood Services, 1800 Alta Vista Drive, Ottawa, ON K1G 4J5, Canada.
authors.forename: Hamza
authors.initials: H
authors.lastname: Ali
authors.affiliation: Canadian Blood Services, 1800 Alta Vista Drive, Ottawa, ON K1G 4J5, Canada.
authors.forename: Valerie S
authors.initials: VS
authors.lastname: Greco-Stewart
authors.affiliation: Case Western Reserve University and University Hospitals Case Medical Center, 11100 Euclid Avenue, Cleveland, OH 44106, USA.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Jacobs
authors.affiliation: Department of Pathology, Case Western Reserve University, Louis Stokes Veterans Administration Medical Center, 10701 East Boulevard, Cleveland, OH 44106, USA.
authors.forename: Roslyn A
authors.initials: RA
authors.lastname: Yomtovian
authors.affiliation: Sanquin Blood Supply Foundation, P.O. Box 9190, 1006 AD Amsterdam, The Netherlands.
authors.forename: Ineke G H
authors.initials: IGH
authors.lastname: Rood
authors.affiliation: Sanquin Blood Supply Foundation, P.O. Box 9190, 1006 AD Amsterdam, The Netherlands.
authors.forename: Dirk
authors.initials: D
authors.lastname: de Korte
authors.affiliation: Canadian Blood Services, 1800 Alta Vista Drive, Ottawa, ON K1G 4J5, Canada.
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Ramírez-Arcos
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D001792:Blood Platelets / Q000382:microbiology*; D003470:Culture Media; D006801:Humans; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D013212:Staphylococcus epidermidis / Q000302:isolation & purification* / Q000502:physiology*
chemical_list: D003470:Culture Media; D011135:Polysaccharides, Bacterial