Experimental staphylococcal infection in mice

Expression of γ-hemolysin regulated bysaeinStaphylococcus aureusstrain Smith 5R

“…However, Smith 5R quickly loses its γ‐hemolysin productivity following serial passaging through subculture, and the shape of the colony changes from rough to smooth. In a original report, Smith described a smooth variant, 5S2, of Smith 5R, which produced neither hemolysin nor coagulase, and was found by subculture in broth (Smith, 1962). Plommet also reported that high levels of spontaneous mutation were involved in the loss of γ‐hemolysin in Smith 5R (Plommet, 1988).…”

“…Staphylococcus aureus strain Smith 5R, of human origin, has been used for γ‐hemolysin purification because of its high γ‐hemolysin productivity which is free from α‐, β‐ and δ‐hemolysins (Smith, 1962; Plommet, 1988). On a human erythrocyte plate, Smith 5R forms a rough‐surfaced colony with a hemolytic halo.…”

“…RNAIII, the transcript of hld , is not only an effector of agr ‐specific regulation, but also mRNA for δ‐hemolysin (Novick, 2000). However, RNAIII is likely not transcribed in Smith 5R because δ‐hemolysin is not produced (Smith, 1962; Plommet, 1988). These data led us to hypothesize that another system could activate the γ‐hemolysin expression, even if the agr system does not function in the Smith 5R strain.…”