![]() aureus surface protein G (SasG) and the serine-aspartate repeat proteins SdrC and SdrD ( 23). Additional surface proteins shown to contribute to bacterial attachment to nasal epithelial cells in vitro include S. ClfB has been shown to bind Fg, as well as cytokeratin 10, by the “dock, lock, and latch” mechanism first defined for the Fg binding proteins SdrG and ClfA ( 21, 22). ClfB is a member of a family of proteins that are structurally related to clumping factor A (ClfA), the archetypal fibrinogen (Fg) binding protein of S. Both ClfB and IsdA were shown to promote adhesion to nasal epithelium in vitro ( 17) and colonization of the nares of rodents ( 18, 19) and, in the case of ClfB, humans ( 20). aureus surface proteins, clumping factor B (ClfB) and iron regulated surface determinant A (IsdA), have been strongly implicated in nasal colonization. aureus can colonize the moist squamous epithelium in the anterior nares ( 15, 16), a process which depends upon specific interactions between bacterial cell adhesins and epithelial cell ligands. aureus infections in both the hospital and the community, with individuals often being infected with the strain that they carry ( 14). Nasal carriage is known to be a risk factor for S. USA300 isolates are the most problematic lineage of CA-MRSA that have emerged and clonally expanded across the United States, reaching epidemic levels in many hospital settings ( 6, 7). In contrast to health care-associated MRSA (HA-MRSA), CA-MRSA strains are more virulent and can spread rapidly among healthy individuals ( 5). ![]() Over the past 20 years, MRSA strains have expanded from health care settings and began infecting otherwise healthy individuals in the community (“community-associated” MRSA ). aureus (MRSA) infections exhibit elevated mortality rates, require longer hospital stays, and exert a higher financial burden on patients and health care institutions ( 4). ![]() Compared to antibiotic-susceptible strains, methicillin-resistant S. aureus infections has increased due to higher rates of colonization and immunosuppressive conditions, greater use of surgical implants, and dramatic increases in antibiotic resistance ( 2, 3). Staphylococcus aureus is a commensal of approximately 20% of the healthy adult population ( 1) and an opportunistic bacterial pathogen able to cause a wide variety of infections ranging in severity from superficial skin lesions to more serious invasive and life-threatening infections, such as endocarditis and septicemia. These results reveal that fibrinogen binding and the capacity to overcome host nutritional limitation are important determinants of MRSA vaginal colonization. Mutants deficient in these pathways did not persist as well during in vivo colonization. The most highly induced genes were those involved in iron acquisition, including the Isd system and siderophore transport systems. Over 25% of the bacterial genes were differentially regulated at all time points during colonization compared to laboratory cultures. To further identify novel factors that promote vaginal colonization, we performed RNA sequencing to determine the transcriptome of MRSA growing in vivo during vaginal carriage at 5 h, 1 day, and 3 days postinoculation. Additionally, we observed that a mutant lacking fibrinogen binding adhesins exhibited decreased persistence within the mouse vagina. Immunohistochemical analysis revealed an increase in neutrophils in the vaginal lumen during MRSA colonization. aureus vaginal carriage and demonstrated that both hospital-associated and community-associated MRSA isolates can colonize the murine vaginal tract. aureus colonization of the female reproductive tract in a mammalian system, we developed a mouse model of S. Currently, little is known about specific factors that promote MRSA vaginal colonization and subsequent infection. aureus can colonize the female vaginal tract, and reports have suggested an increase in MRSA infections in pregnant and postpartum women as well as outbreaks in newborn nurseries. aureus (MRSA) infections have continued to increase despite widespread preventative measures. Staphylococcus aureus is an important pathogen responsible for nosocomial and community-acquired infections in humans, and methicillin-resistant S.
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