Neosporin - Will it be affected on S. Auerus? (Mar/09/2005 )

I need to write a paper on why I thought the Neosporin would not be effected on the Staphylococcus auerus? The only reason why I thought it would not because companies make products out to be more than what they are, now maybe it does have an effect and my agar results got contaminated not sure. What are your thoughts?

Neosporin, which is the swiss tradename for polymyxin B (yes?), should not be a effective antibiotic against S.aureus, since S.aureus is a gram-positive bacterium, while polymyxin B's mode of action is the interaction with the periplasmic membran components such as Lipid A of LPS of gram-negative bacteria, thus disorganising the (gram-negative) bacterial cell-membrane. usually is's recommended to use polymyxin B against gram-negative rods only.

mike