title: Role of the Emp Pilus Subunits of Enterococcus faecium in Biofilm Formation, Adherence to Host Extracellular Matrix Components, and Experimental Infection.
abstract: Enterococcus faecium is an important cause of hospital-associated infections, including urinary tract infections (UTIs), bacteremia, and infective endocarditis. Pili have been shown to play a role in the pathogenesis of Gram-positive bacteria, including E. faecium We previously demonstrated that a nonpiliated ΔempABC::cat derivative of E. faecium TX82 was attenuated in biofilm formation and in a UTI model. Here, we studied the contributions of the individual pilus subunits EmpA, EmpB, and EmpC to pilus architecture, biofilm formation, adherence to extracellular matrix (ECM) proteins, and infection. We identified EmpA as the tip of the pili and found that deletion of empA reduced biofilm formation to the same level as deletion of the empABC operon, a phenotype that was restored by reconstituting in situ the empA gene. Deletion of empB also caused a reduction in biofilm, while EmpC was found to be dispensable. Significant reductions in adherence to fibrinogen and collagen type I were observed with deletion of empA and empB, while deletion of empC had no adherence defect. Furthermore, we showed that each deletion mutant was significantly attenuated in comparison to the isogenic parental strain, TX82, in a mixed-inoculum UTI model (P < 0.001 to 0.048), that reconstitution of empA restored virulence in the UTI model, and that deletion of empA also resulted in attenuation in an infective endocarditis model (P = 0.0088). Our results indicate that EmpA and EmpB, but not EmpC, contribute to biofilm and adherence to ECM proteins; however, all the Emp pilins are important for E. faecium to cause infection in the urinary tract.
authors.affiliation: Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Health Science Center at Houston, Houston, Texas, USA.|Center for the Study of Emerging and Re-emerging Pathogens, The University of Texas Health Science Center at Houston, Houston, Texas, USA.|Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, Texas, USA.
authors.forename: Maria Camila
authors.initials: MC
authors.lastname: Montealegre
authors.affiliation: Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Health Science Center at Houston, Houston, Texas, USA.|Center for the Study of Emerging and Re-emerging Pathogens, The University of Texas Health Science Center at Houston, Houston, Texas, USA.
authors.forename: Kavindra V
authors.initials: KV
authors.lastname: Singh
authors.affiliation: Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Health Science Center at Houston, Houston, Texas, USA.
authors.forename: Sudha R
authors.initials: SR
authors.lastname: Somarajan
authors.affiliation: Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Health Science Center at Houston, Houston, Texas, USA.
authors.forename: Puja
authors.initials: P
authors.lastname: Yadav
authors.affiliation: Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, Texas, USA.
authors.forename: Chungyu
authors.initials: C
authors.lastname: Chang
authors.affiliation: Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Health Science Center at Houston, Houston, Texas, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Spencer
authors.affiliation: Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Health Science Center at Houston, Houston, Texas, USA.|Center for the Study of Emerging and Re-emerging Pathogens, The University of Texas Health Science Center at Houston, Houston, Texas, USA.
authors.forename: Jouko
authors.initials: J
authors.lastname: Sillanpää
authors.affiliation: Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, Texas, USA.
authors.forename: Hung
authors.initials: H
authors.lastname: Ton-That
authors.affiliation: Department of Internal Medicine, Division of Infectious Diseases, The University of Texas Health Science Center at Houston, Houston, Texas, USA bem.asst@uth.tmc.edu.|Center for the Study of Emerging and Re-emerging Pathogens, The University of Texas Health Science Center at Houston, Houston, Texas, USA.|Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, Texas, USA.
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Murray
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D018441:Biofilms / Q000254:growth & development*; D024042:Collagen Type I / Q000378:metabolism; D004195:Disease Models, Animal; D004697:Endocarditis, Bacterial / Q000382:microbiology / Q000473:pathology; D016984:Enterococcus faecium / Q000235:genetics / Q000502:physiology*; D005109:Extracellular Matrix / Q000378:metabolism*; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D017353:Gene Deletion; D005816:Genetic Complementation Test; D016908:Gram-Positive Bacterial Infections / Q000382:microbiology* / Q000473:pathology; D008297:Male; D008813:Mice, Inbred ICR; D009876:Operon; D001678:Organelle Biogenesis; D017207:Rats, Sprague-Dawley; D014552:Urinary Tract Infections / Q000382:microbiology / Q000473:pathology; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D024042:Collagen Type I; D037521:Virulence Factors; D036781:Fimbriae Proteins; D005340:Fibrinogen