title: Biofilm-Forming Methicillin-Resistant Staphylococcus aureus Survive in Kupffer Cells and Exhibit High Virulence in Mice.
abstract: Although Staphylococcus aureus is part of the normal body flora, heavy usage of antibiotics has resulted in the emergence of methicillin-resistant strains (MRSA). MRSA can form biofilms and cause indwelling foreign body infections, bacteremia, soft tissue infections, endocarditis, and osteomyelitis. Using an in vitro assay, we screened 173 clinical blood isolates of MRSA and selected 20 high-biofilm formers (H-BF) and low-biofilm formers (L-BF). These were intravenously administered to mice and the general condition of mice, the distribution of bacteria, and biofilm in the liver, lung, spleen, and kidney were investigated. MRSA count was the highest in the liver, especially within Kupffer cells, which were positive for acid polysaccharides that are associated with intracellular biofilm. After 24 h, the general condition of the mice worsened significantly in the H-BF group. In the liver, bacterial deposition and aggregation and the biofilm-forming spot number were all significantly greater for H-BF group than for L-BF. CFU analysis revealed that bacteria in the H-BF group survived for long periods in the liver. These results indicate that the biofilm-forming ability of MRSA is a crucial factor for intracellular persistence, which could lead to chronic infections.
authors.affiliation: Department of Plastic, Reconstructive and Aesthetic Surgery, Faculty of Medicine, Fukuoka University, Fukuoka 814-0180, Japan. oyt1974@yahoo.co.jp.
authors.forename: Takuto
authors.initials: T
authors.lastname: Oyama
authors.affiliation: Department of Pharmacy, Fukuoka University Chikushi Hospital, Chikusino 818-8502, Japan. karl-101@hotmail.co.jp.
authors.forename: Motoyasu
authors.initials: M
authors.lastname: Miyazaki
authors.affiliation: Department of Medical Oncology, Hematology, and Infectious Diseases, Faculty of Medicine, Fukuoka University, Fukuoka 814-0180, Japan. myoshimura@fukuoka-u.ac.jp.
authors.forename: Michinobu
authors.initials: M
authors.lastname: Yoshimura
authors.affiliation: Department of Medical Oncology, Hematology, and Infectious Diseases, Faculty of Medicine, Fukuoka University, Fukuoka 814-0180, Japan. takattol@cis.fukuoka-u.ac.jp.
authors.forename: Tohru
authors.initials: T
authors.lastname: Takata
authors.affiliation: Department of Plastic, Reconstructive and Aesthetic Surgery, Faculty of Medicine, Fukuoka University, Fukuoka 814-0180, Japan. ohjimi@fukuoka-u.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohjimi
authors.affiliation: Central Laboratory for Pathology and Morphology, Department of Pathology, Faculty of Medicine, Fukuoka University, Fukuoka 814-0180, Japan. sjimi@fukuoka-u.ac.jp.
authors.forename: Shiro
authors.initials: S
authors.lastname: Jimi
mesh_terms: D000818:Animals; D058491:Bacterial Load; D018441:Biofilms / Q000254:growth & development*; D005260:Female; D007728:Kupffer Cells / Q000382:microbiology*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000254:growth & development* / Q000378:metabolism / Q000472:pathogenicity*; D008810:Mice, Inbred C57BL; D050296:Microbial Viability; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D013203:Staphylococcal Infections / Q000097:blood / Q000382:microbiology*; D013997:Time Factors; D014774:Virulence
chemical_list: D011135:Polysaccharides, Bacterial
keywords: Kupffer cells; MRSA; biofilm; intracellular persistence; mice; virulence