Staph is gold-colored

• is there some sort of advantage conferred by the pigment to make the organism bother with making these molecules?

• these molecules resemble β-carotene, and carotene is a very effective antioxidant

• how do WBCs kill bacteria? they generate oxidants

• so S. aureus decorating itself with antioxidants

Antioxidant properties experiment

• knock out pigment—Staph is much more susceptible to oxidants

• give Strep the pigment—Strep is more resistant to oxidants

• how do we confirm that this is indeed the factor involved? add something that blocks oxidation—for example, a deficiency in NADPH oxidase, leading to a disease we call chronic granulomatous disease

• in CGD mice models, bacterial pigment don’t matter, presumably because there is no oxidative burst

• in a normal person, pigmented leads to abscess and non-pigmented does not lead to abscess

Then, can we block synthesis of Staph pigment?

• a cholesterol drug inferior to statins treated S. aureus infections by making the bacteria susceptible to oxidative burst

Category: Microbiology Notes