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Key role for clumping factor B in Staphylococcus aureus nasal colonization of humans.

Wertheim HF, Walsh E, Choudhurry R, Melles DC, Boelens HA, Miajlovic H, Verbrugh HA, Foster T, van Belkum A - PLoS Med. (2008)

Bottom Line: Staphylococcus aureus permanently colonizes the vestibulum nasi of one-fifth of the human population, which is a risk factor for autoinfection.The precise mechanisms whereby S. aureus colonizes the nose are still unknown.The human colonization model, in combination with in vitro data, shows that the ClfB protein is a major determinant of nasal-persistent S. aureus carriage and is a candidate target molecule for decolonization strategies.

View Article: PubMed Central - PubMed

Affiliation: Erasmus MC, University Medical Center Rotterdam, Department of Medical Microbiology and Infectious Diseases, Rotterdam, The Netherlands. h.wertheim@erasmusmc.nl

ABSTRACT

Background: Staphylococcus aureus permanently colonizes the vestibulum nasi of one-fifth of the human population, which is a risk factor for autoinfection. The precise mechanisms whereby S. aureus colonizes the nose are still unknown. The staphylococcal cell-wall protein clumping factor B (ClfB) promotes adhesion to squamous epithelial cells in vitro and might be a physiologically relevant colonization factor.

Methods and findings: We define the role of the staphylococcal cytokeratin-binding protein ClfB in the colonization process by artificial inoculation of human volunteers with a wild-type strain and its single locus ClfB knock-out mutant. The wild-type strain adhered to immobilized recombinant human cytokeratin 10 (CK10) in a dose-dependent manner, whereas the ClfB(-) mutant did not. The wild-type strain, when grown to the stationary phase in a poor growth medium, adhered better to CK10, than when the same strain was grown in a nutrient-rich environment. Nasal cultures show that the mutant strain is eliminated from the nares significantly faster than the wild-type strain, with a median of 3 +/- 1 d versus 7 +/- 4 d (p = 0.006). Furthermore, the wild-type strain was still present in the nares of 3/16 volunteers at the end of follow-up, and the mutant strain was not.

Conclusions: The human colonization model, in combination with in vitro data, shows that the ClfB protein is a major determinant of nasal-persistent S. aureus carriage and is a candidate target molecule for decolonization strategies.

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ClfB Expression Experiments(A) Bacterial growth and ClfB expression in RPMI. Strains 8325–4, DU5997, and SH1000 were grown in RPMI, and samples were taken at regular intervals to monitor growth.(B) Samples taken at early exponential, early stationary, and late stationary phases of growth were analyzed by Western immunoblotting. Lanes 1, 2, and 3 show ClfB expression from strain 8325–4 at early exponential, early stationary, and late stationary growth phases, respectively. Lanes 4, 5, and 6 show ClfB expression from strain DU5997 at early exponential, early stationary, and late stationary growth phases, respectively. Lanes 7, 8, and 9 show ClfB expression from SH1000 at early exponential, early stationary, and late stationary growth phases, respectively.(C) Bacterial growth and ClfB expression in TSB. Strain 8325–4 was grown in TSB, and samples were taken at regular intervals to monitor growth.(D) Western immunoblotting was carried out to detect ClfB expression at early exponential, early stationary, and late stationary phases of growth. Lanes 1, 2, and 3 show ClfB expression from strain 8325–4 grown in TSB at early exponential, early stationary, and late stationary growth phases, respectively.
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pmed-0050017-g002: ClfB Expression Experiments(A) Bacterial growth and ClfB expression in RPMI. Strains 8325–4, DU5997, and SH1000 were grown in RPMI, and samples were taken at regular intervals to monitor growth.(B) Samples taken at early exponential, early stationary, and late stationary phases of growth were analyzed by Western immunoblotting. Lanes 1, 2, and 3 show ClfB expression from strain 8325–4 at early exponential, early stationary, and late stationary growth phases, respectively. Lanes 4, 5, and 6 show ClfB expression from strain DU5997 at early exponential, early stationary, and late stationary growth phases, respectively. Lanes 7, 8, and 9 show ClfB expression from SH1000 at early exponential, early stationary, and late stationary growth phases, respectively.(C) Bacterial growth and ClfB expression in TSB. Strain 8325–4 was grown in TSB, and samples were taken at regular intervals to monitor growth.(D) Western immunoblotting was carried out to detect ClfB expression at early exponential, early stationary, and late stationary phases of growth. Lanes 1, 2, and 3 show ClfB expression from strain 8325–4 grown in TSB at early exponential, early stationary, and late stationary growth phases, respectively.

Mentions: We compared the growth of strain 8325–4 with SH1000 (which has a fully functional SigB), and with DU5997 (which is defective in ClfB). Growth was carried out in a medium reflective of growth conditions in vivo. The results show that bacteria grew more slowly and to a much lower optical density in stationary phase in RPMI as compared to TSB. Doubling times for 8325–4 were 108 min in RPMI and 40 min in TSB. In RPMI, the growth rates and yields of 8325–4 and DU5997 were indistinguishable, whereas SH1000 grew slightly faster (doubling time 96 min) and to a higher density (Figure 2A).


Key role for clumping factor B in Staphylococcus aureus nasal colonization of humans.

Wertheim HF, Walsh E, Choudhurry R, Melles DC, Boelens HA, Miajlovic H, Verbrugh HA, Foster T, van Belkum A - PLoS Med. (2008)

ClfB Expression Experiments(A) Bacterial growth and ClfB expression in RPMI. Strains 8325–4, DU5997, and SH1000 were grown in RPMI, and samples were taken at regular intervals to monitor growth.(B) Samples taken at early exponential, early stationary, and late stationary phases of growth were analyzed by Western immunoblotting. Lanes 1, 2, and 3 show ClfB expression from strain 8325–4 at early exponential, early stationary, and late stationary growth phases, respectively. Lanes 4, 5, and 6 show ClfB expression from strain DU5997 at early exponential, early stationary, and late stationary growth phases, respectively. Lanes 7, 8, and 9 show ClfB expression from SH1000 at early exponential, early stationary, and late stationary growth phases, respectively.(C) Bacterial growth and ClfB expression in TSB. Strain 8325–4 was grown in TSB, and samples were taken at regular intervals to monitor growth.(D) Western immunoblotting was carried out to detect ClfB expression at early exponential, early stationary, and late stationary phases of growth. Lanes 1, 2, and 3 show ClfB expression from strain 8325–4 grown in TSB at early exponential, early stationary, and late stationary growth phases, respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2194749&req=5

pmed-0050017-g002: ClfB Expression Experiments(A) Bacterial growth and ClfB expression in RPMI. Strains 8325–4, DU5997, and SH1000 were grown in RPMI, and samples were taken at regular intervals to monitor growth.(B) Samples taken at early exponential, early stationary, and late stationary phases of growth were analyzed by Western immunoblotting. Lanes 1, 2, and 3 show ClfB expression from strain 8325–4 at early exponential, early stationary, and late stationary growth phases, respectively. Lanes 4, 5, and 6 show ClfB expression from strain DU5997 at early exponential, early stationary, and late stationary growth phases, respectively. Lanes 7, 8, and 9 show ClfB expression from SH1000 at early exponential, early stationary, and late stationary growth phases, respectively.(C) Bacterial growth and ClfB expression in TSB. Strain 8325–4 was grown in TSB, and samples were taken at regular intervals to monitor growth.(D) Western immunoblotting was carried out to detect ClfB expression at early exponential, early stationary, and late stationary phases of growth. Lanes 1, 2, and 3 show ClfB expression from strain 8325–4 grown in TSB at early exponential, early stationary, and late stationary growth phases, respectively.
Mentions: We compared the growth of strain 8325–4 with SH1000 (which has a fully functional SigB), and with DU5997 (which is defective in ClfB). Growth was carried out in a medium reflective of growth conditions in vivo. The results show that bacteria grew more slowly and to a much lower optical density in stationary phase in RPMI as compared to TSB. Doubling times for 8325–4 were 108 min in RPMI and 40 min in TSB. In RPMI, the growth rates and yields of 8325–4 and DU5997 were indistinguishable, whereas SH1000 grew slightly faster (doubling time 96 min) and to a higher density (Figure 2A).

Bottom Line: Staphylococcus aureus permanently colonizes the vestibulum nasi of one-fifth of the human population, which is a risk factor for autoinfection.The precise mechanisms whereby S. aureus colonizes the nose are still unknown.The human colonization model, in combination with in vitro data, shows that the ClfB protein is a major determinant of nasal-persistent S. aureus carriage and is a candidate target molecule for decolonization strategies.

View Article: PubMed Central - PubMed

Affiliation: Erasmus MC, University Medical Center Rotterdam, Department of Medical Microbiology and Infectious Diseases, Rotterdam, The Netherlands. h.wertheim@erasmusmc.nl

ABSTRACT

Background: Staphylococcus aureus permanently colonizes the vestibulum nasi of one-fifth of the human population, which is a risk factor for autoinfection. The precise mechanisms whereby S. aureus colonizes the nose are still unknown. The staphylococcal cell-wall protein clumping factor B (ClfB) promotes adhesion to squamous epithelial cells in vitro and might be a physiologically relevant colonization factor.

Methods and findings: We define the role of the staphylococcal cytokeratin-binding protein ClfB in the colonization process by artificial inoculation of human volunteers with a wild-type strain and its single locus ClfB knock-out mutant. The wild-type strain adhered to immobilized recombinant human cytokeratin 10 (CK10) in a dose-dependent manner, whereas the ClfB(-) mutant did not. The wild-type strain, when grown to the stationary phase in a poor growth medium, adhered better to CK10, than when the same strain was grown in a nutrient-rich environment. Nasal cultures show that the mutant strain is eliminated from the nares significantly faster than the wild-type strain, with a median of 3 +/- 1 d versus 7 +/- 4 d (p = 0.006). Furthermore, the wild-type strain was still present in the nares of 3/16 volunteers at the end of follow-up, and the mutant strain was not.

Conclusions: The human colonization model, in combination with in vitro data, shows that the ClfB protein is a major determinant of nasal-persistent S. aureus carriage and is a candidate target molecule for decolonization strategies.

Show MeSH
Related in: MedlinePlus