staphylococcus aureus on blood agar visualizing grampositivevariable cocci and betahemolysis

staphylococcus aureus gram positive variable nonmotile coccus bacteria beta hemolysis saprotrophic blood agar pathogenic microbiology infection culture medium clinical research laboratory antibiotic resistance cocci bacteriology biofilm human pathogen skin flora disease virulence diagnosis healthcare techniques sterile environment colony morphology growth conditions infectious agents stain medical susceptibility specimens health zoonotic