title: Early staphylococcal biofilm formation on solid orthopaedic implant materials: in vitro study.
abstract: Biofilms forming on the surface of biomaterials can cause intractable implant-related infections. Bacterial adherence and early biofilm formation are influenced by the type of biomaterial used and the physical characteristics of implant surface. In this in vitro research, we evaluated the ability of Staphylococcus epidermidis, the main pathogen in implant-related infections, to form biofilms on the surface of the solid orthopaedic biomaterials, oxidized zirconium-niobium alloy, cobalt-chromium-molybdenum alloy (Co-Cr-Mo), titanium alloy (Ti-6Al-4V), commercially pure titanium (cp-Ti) and stainless steel. A bacterial suspension of Staphylococcus epidermidis strain RP62A (ATCC35984) was added to the surface of specimens and incubated. The stained biofilms were imaged with a digital optical microscope and the biofilm coverage rate (BCR) was calculated. The total amount of biofilm was determined with the crystal violet assay and the number of viable cells in the biofilm was counted using the plate count method. The BCR of all the biomaterials rose in proportion to culture duration. After culturing for 2-4 hours, the BCR was similar for all materials. However, after culturing for 6 hours, the BCR for Co-Cr-Mo alloy was significantly lower than for Ti-6Al-4V, cp-Ti and stainless steel (P<0.05). The absorbance value determined in the crystal violet assay and the number of viable cells on Co-Cr-Mo were not significantly lower than for the other materials (P>0.05). These results suggest that surface properties, such as hydrophobicity or the low surface free energy of Co-Cr-Mo, may have some influence in inhibiting or delaying the two-dimensional expansion of biofilm on surfaces with a similar degree of smoothness.
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Hironobu
authors.initials: H
authors.lastname: Koseki
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Yonekura
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Shida
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Itaru
authors.initials: I
authors.lastname: Yoda
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Horiuchi
authors.affiliation: Department of Laboratory Medicine, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Yoshitomo
authors.initials: Y
authors.lastname: Morinaga
authors.affiliation: Department of Laboratory Medicine, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Katsunori
authors.initials: K
authors.lastname: Yanagihara
authors.affiliation: Division of Medical Devices, National Institute of Health Sciences, Tokyo, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Sakoda
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Osaki
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Tomita
mesh_terms: D000497:Alloys / Q000627:therapeutic use; D001422:Bacterial Adhesion / Q000502:physiology; D001672:Biocompatible Materials / Q000627:therapeutic use*; D018441:Biofilms / Q000254:growth & development*; D057927:Hydrophobic and Hydrophilic Interactions; D009985:Orthopedics / Q000379:methods; D019736:Prostheses and Implants / Q000382:microbiology*; D013203:Staphylococcal Infections / Q000382:microbiology; D013212:Staphylococcus epidermidis / Q000254:growth & development*; D013499:Surface Properties
chemical_list: D000497:Alloys; D001672:Biocompatible Materials