Virulence adaption to environment promotes the age-dependent nasal colonization of Staphylococcus aureus

Abstract

Staphylococcus aureus is an important human commensal bacteria colonizing the human body, especially the nasal cavity. The nasal carriage can be a source of S. aureus bacteremia. However, the bacterial factors contributing to nasal colonization are not completely understood. By analysing S. aureus strains from the nasal cavity of the children, young adults, and seniors, we found that the low activity of the SaeRS two-component system (TCS) is an important determinant for S. aureus to colonize in seniors. The senior group isolates of S. aureus showed a rather distinct sequence type composition as compared with other age group isolates. The senior group isolates showed not only a lower gene carriage of enterotoxins a, c, and q but also lower hemolytic activity against human red blood cells. Of regulators affecting hemolysin production (i.e. agr , saeRS , rot , rsp , and sarS ), only the SaeRS TCS showed an age-dependent decrease of activity. The decreased virulence and better colonization ability of the senior group isolates of S. aureus were confirmed in the mouse model. The senior group isolates showed the lowest survival and the best adhesion and colonizing ability. Also, the senior nasal secretions supported S. aureus survival better than the child and young adult nasal secretions. These results indicated that the senior nasal cavity favours colonization of S. aureus with higher adhesion and lower virulence, to which the reduced SaeRS TCS activity contributes. Taken together, our results illustrate an example of bacterial adaptation to the changing host environment.

Commensal Staphylococcus epidermidis Defends against Staphylococcus aureus through SaeRS Two-Component System

“…Based on our previous findings, it appears that the activity of the SaeRS TCS contributes to nasal colonization. Specifically, we observed enhanced survival of strains with reduced SaeRS TCS activity in the nares of human subjects . SaeRS TCS promotes the pathogenesis of S.…”

“…epidermidis, develop an arsenal of mechanisms defending against S. aureus. , In the study, we elucidated that heat-sensitive small molecules secreted by S. epidermidis effectively inhibit the hemolytic activity of S.…”

“…CoNS, especially S. epidermidis, develop an arsenal of mechanisms defending against S. aureus . 15 , 16 In the study, we elucidated that heat-sensitive small molecules secreted by S. epidermidis effectively inhibit the hemolytic activity of S. aureus by down-regulating the SaeRS TCS. Critically, S. epidermidis is capable of efficiently inhibiting S. aureus virulence in vivo.…”

“…Specifically, we observed enhanced survival of strains with reduced SaeRS TCS activity in the nares of human subjects. 16 SaeRS TCS promotes the pathogenesis of S. aureus by controlling the expression of over 20 virulence factors including α-hemolysin ( hla ). 17 , 18 As one of the representative virulence factors, Hla is responsible for the hemolytic activity of S. aureus by disrupting red blood cells.…”

Enterotoxin Gene Cluster and selX Are Associated with Atopic Dermatitis Severity—A Cross-Sectional Molecular Study of Staphylococcus aureus Superantigens

“…The hypothesis regarding the association with skin dryness has already been put forward. The inverse association with the extent of skin lesions on nonlesional skin and the nose, as well as lower itch severity could be explained by the fact that the expression of genes encoding SAgs is regulated by quorum-sensing systems such as agr [ 39 ]. These are activated after the density of S. aureus reaches a threshold in a given microniche.…”