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Full-Text Articles in Medicine and Health Sciences
Heparin Stimulates Staphylococcus Aureus Biofilm Formation, Robert M. Q. Shanks, Niles P. Donegan, Martha L. Graber, Sarah E. Buckingham, Michael Zegans, Ambrose Cheung, George A. O'Toole
Heparin Stimulates Staphylococcus Aureus Biofilm Formation, Robert M. Q. Shanks, Niles P. Donegan, Martha L. Graber, Sarah E. Buckingham, Michael Zegans, Ambrose Cheung, George A. O'Toole
Dartmouth Scholarship
Heparin, known for its anticoagulant activity, is commonly used in catheter locks. Staphylococcus aureus, a versatile human and animal pathogen, is commonly associated with catheter-related bloodstream infections and has evolved a number of mechanisms through which it adheres to biotic and abiotic surfaces. We demonstrate that heparin increased biofilm formation by several S. aureus strains. Surface coverage and the kinetics of biofilm formation were stimulated, but primary attachment to the surface was not affected. Heparin increased S. aureus cell-cell interactions in a protein synthesis-dependent manner. The addition of heparin rescued biofilm formation of hla, ica, and sarA …
Sara Positively Controls Bap-Dependent Biofilm Formation In Staphylococcus Aureus, María P. Trotonda, Adhar C. Manna, Ambrose L. Cheung, Iñigo Lasa, José R. Penadés
Sara Positively Controls Bap-Dependent Biofilm Formation In Staphylococcus Aureus, María P. Trotonda, Adhar C. Manna, Ambrose L. Cheung, Iñigo Lasa, José R. Penadés
Dartmouth Scholarship
The biofilm-associated protein Bap is a staphylococcal surface protein involved in biofilm formation. We investigated the influence of the global regulatory locus sarA on bap expression and Bap-dependent biofilm formation in three unrelated Staphylococcus aureus strains. The results showed that Bap-dependent biofilm formation was diminished in the sarA mutants by an agr-independent mechanism. Complementation studies using a sarA clone confirmed that the defect in biofilm formation was due to the sarA mutation. As expected, the diminished capacity to form biofilms in the sarA mutants correlated with the decreased presence of Bap in the bacterial surface. Using transcriptional fusion and …
Role Of The Distal Sara Promoters In Sara Expression In Staphylococcus Aureus, Ambrose L. Cheung, Adhar C. Manna
Role Of The Distal Sara Promoters In Sara Expression In Staphylococcus Aureus, Ambrose L. Cheung, Adhar C. Manna
Dartmouth Scholarship
The global regulatory locus sarA comprises a 375-bp open reading frame that is driven by three promoters, the proximal P1 and distal P3 and P2 promoters. We mutated the weaker P3 and P2 promoters to ascertain the effect of the change on SarA protein and target gene expression. Our results indicated that the solely active P1 promoter led to a lower SarA protein level, which has an effect on agr transcription and subsequently had corresponding effects on hla, sspA, and spa transcription, probably in both agr-independent and agr-dependent manners.
Thymidine-Dependent Staphylococcus Aureus Small-Colony Variants Are Associated With Extensive Alterations In Regulator And Virulence Gene Expression Profiles, Barbara C. Kahl, Gunnar Belling, Petra Becker, Indranil Chatterjee, Katrin Wardecki, Karin Hilgert, Ambrose Cheung
Thymidine-Dependent Staphylococcus Aureus Small-Colony Variants Are Associated With Extensive Alterations In Regulator And Virulence Gene Expression Profiles, Barbara C. Kahl, Gunnar Belling, Petra Becker, Indranil Chatterjee, Katrin Wardecki, Karin Hilgert, Ambrose Cheung
Dartmouth Scholarship
Chronic airway infection is a hallmark of cystic fibrosis (CF) and many CF patients are infected persistently by Staphylococcus aureus. Thymidine-dependent trimethoprim-sulfamethoxazole (SXT)-resistant S. aureus small-colony variants (SCVs), often in combination with isogenic normal S. aureus phenotypes, are highly prevalent and persistent in airway secretions of CF patients due to long-term SXT therapy (B. Kahl, M. Herrmann, A. S. Everding, H. G. Koch, K. Becker, E. Harms, R. A. Proctor, and G.
Rat/Mgra, A Regulator Of Autolysis, Is A Regulator Of Virulence Genes In Staphylococcus Aureus, Susham Ingavale, Willem Van Wamel, Thanh T. Luong, Chia Y. Lee, Ambrose L. Cheung
Rat/Mgra, A Regulator Of Autolysis, Is A Regulator Of Virulence Genes In Staphylococcus Aureus, Susham Ingavale, Willem Van Wamel, Thanh T. Luong, Chia Y. Lee, Ambrose L. Cheung
Dartmouth Scholarship
We have previously identified mgrA (rat) as a regulator of autolysis in Staphylococcus aureus. Besides its effect on autolytic activity, we recently found alterations in the expression of regulator and target virulence genes in the mgrA mutant. Northern analysis and transcription fusion assays showed that inactivation of mgrA has led to the downregulation of RNAIII of agr and hla and upregulation of sarS and spa. Although both SarA and agr are activators of α-hemolysin and a repressors of protein A synthesis, we found that the transcription of sarA was not affected in the mgrA mutant and …