title: Formation and properties of in vitro biofilms of ica-negative Staphylococcus epidermidis clinical isolates.
abstract: Coagulase-negative Staphylococcus epidermidis has become the leading cause of foreign-body infections due to its biofilm formation on all kinds of medical-device surfaces. The biofilm development of S. epidermidis includes two steps: the initial attachment phase and the accumulative phase. In the accumulative phase, the polysaccharide intercellular adhesin (PIA), encoded by the icaADBC locus, is the major component mediating intercellular adhesion. However, recent studies have revealed the emergence of biofilm-positive/ica-negative staphylococcal clinical isolates. In this report, two ica-negative S. epidermidis clinical strains, SE1 and SE4, exhibited their heterogeneity in biofilm architecture under static and flow conditions, compared with the biofilm-positive/ica-positive RP62A strain. Strains with this type of absence of PIA from biofilms also displayed intermediate resistance to vancomycin. More importantly, the cells of both SE1 and SE4 strains were more tolerant than those of RP62A to exposure to lysostaphin and vancomycin. Based on the results, it is suggested that the biofilm-positive/ica-negative strain represents a newly emergent subpopulation of S. epidermidis clinical strains, arising from selection by antibiotics in the nosocomial milieu, which displays a survival advantage in its host environment. Recent epidemiological data support this suggestion, by showing a tendency towards an increasing proportion of this subpopulation in staphylococci-associated infections.
authors.affiliation: Key Laboratory of Medical Molecular Virology of Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Medical School of Fudan University, 138 Yixueyuan Road, Shanghai 200032, China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Qin
authors.affiliation: Key Laboratory of Medical Molecular Virology of Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Medical School of Fudan University, 138 Yixueyuan Road, Shanghai 200032, China.
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Yang
authors.affiliation: Infection Microbiology Group, BioCentrum-DTU, Technical University of Denmark, DK-2800 Lyngby, Denmark.
authors.forename: Lei
authors.initials: L
authors.lastname: Yang
authors.affiliation: Key Laboratory of Medical Molecular Virology of Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Medical School of Fudan University, 138 Yixueyuan Road, Shanghai 200032, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Medical Molecular Virology of Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Medical School of Fudan University, 138 Yixueyuan Road, Shanghai 200032, China.
authors.forename: Yuanzhu
authors.initials: Y
authors.lastname: Ou
authors.affiliation: Infection Microbiology Group, BioCentrum-DTU, Technical University of Denmark, DK-2800 Lyngby, Denmark.
authors.forename: Soeren
authors.initials: S
authors.lastname: Molin
authors.affiliation: Key Laboratory of Medical Molecular Virology of Ministry of Education and Ministry of Public Health, Institute of Medical Microbiology and Institutes of Biomedical Sciences, Medical School of Fudan University, 138 Yixueyuan Road, Shanghai 200032, China.
authors.forename: Di
authors.initials: D
authors.lastname: Qu
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018441:Biofilms; D003030:Coagulase / Q000235:genetics* / Q000378:metabolism; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D018740:Genetic Heterogeneity; D005838:Genotype; D006801:Humans; D008248:Lysostaphin / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D008954:Models, Biological; D013045:Species Specificity; D013203:Staphylococcal Infections / Q000382:microbiology; D013212:Staphylococcus epidermidis / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D003030:Coagulase; D004269:DNA, Bacterial; D014640:Vancomycin; D008248:Lysostaphin