Expert: Walter Hintz - 1/31/2007

Question
My question is this:  Since you can't identify bacteria from a Gram stain, why might a physician perform a Gram stain on a smaple before prescribing an antibiotic?

I put as the answer:  A Gram stain might be performed because it can help pinpoint the possible cause of infection, and in some cases it may be possible to begin drug therapy on the basis of the stain.

I just wanted to make sure that my answer was correct.

Thank you in advance for your help!

Answer
Hi tabitha
 Gram positive and gram negative bacteria react differently to different antibiotics.  Gram positives like strep and staph for are more likely to respond to the penicillins.  Gram negatives like E. coli are not affected by these antibiotics.