Gram-positive cocci are often isolated from clinical samples. It is important to be able to distinguish these organisms from one another because while some are normal flora, others can be pathogenic.

LPS is an endotoxin that is important in triggering the body’s immune response. Gram-negative cells will stain pink with the Gram stain. If your staining procedure was successful you will see Gram ...

"Normal flora" include Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, and anaerobes such as Bacteroides species, anaerobic gram-positive cocci, and Fusobacterium species.