TY - JOUR
T1 - Role of the Emp pilus subunits of Enterococcus faecium in biofilm formation, adherence to host extracellular matrix components, and experimental infection
AU - Montealegre, Maria Camila
AU - Singh, Kavindra V.
AU - Somarajan, Sudha R.
AU - Yadav, Puja
AU - Chang, Chungyu
AU - Spencer, Robert
AU - Sillanpää, Jouko
AU - Ton-That, Hung
AU - Murray, Barbara E.
N1 - Funding Information:
This work, including the efforts of Barbara E Murray, was funded by HHS | National Institutes of Health (NIH) (R01 AI047923). This work, including the efforts of Hung Ton-That, was funded by HHS | National Institutes of Health (NIH) (R01 DE017382).
Publisher Copyright:
© 2016, American Society for Microbiology. All Rights Reserved.
PY - 2016/5/1
Y1 - 2016/5/1
N2 - 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.
AB - 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.
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U2 - 10.1128/IAI.01396-15
DO - 10.1128/IAI.01396-15
M3 - Article
C2 - 26930703
AN - SCOPUS:84965124178
SN - 0019-9567
VL - 84
SP - 1491
EP - 1500
JO - Infection and Immunity
JF - Infection and Immunity
IS - 5
ER -