This study is an exploration of the dysfunction of the agr system, expressed by the variability of expression of hemolysis on blood agar of nosocomial strains of Staphylococcus aureus, isolated from hospital staff, in order to establish a correlation between the expressed phenotypes and their multidrug resistance as well as their ability to colonize biological membranes.
We obtained four distinct phenotypes after 48 hours of incubation on blood agar obtained from three phenotypes obtained after 24 h of incubation.
The polymorphism expressed is notably marked by a hemolysin deficiency represented by a rate of 64.06%. 18.18% of the strains tested expressed a delayed hemolysis while the rest of the strains expressed hemolysis after only 24 h.
The results obtained indicate that simultaneous consideration of the criteria, of the hemolysin deficiency and the reduced size of the S. aureus colonies obtained, can be used as a predictive marker of resistance to methicillin.
91.46% of the strains that showed resistance to the antibiotics tested belong to the phenotypes which expressed a simultaneous hemolysin deficiency as well as to the pigmentation capacity, these results announce a possible relationship between antibiotic resistance and suppression or alteration of the loci specific to the two criteria considered.


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