Why does Tetracycline work better than Penicillin and Vancomycin?

I understand that for Gram-negative bacteria, Penicillin and Vancomycin don't work, but for Gram-positive, what makes it work better? Vancomycin sounds similar to it should be more effective, with its toxicity and "last resort" sign.

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Answers:

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I think you're in my class, lol, I'm doing the same lab.

Long story short, Tetracycline does not attack the cell wall of the germs, it stops translation. Source(s): http://en.wikipedia.org/wiki/Tetracycline#Cautions.2C_contraindications.2C_side_effects

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Toxicity aside, Vancocin (vancomycin) is not absorbed from the gastrointestinal tract. It is only used orally to treat C. difficile colitis which is lasting or resistant to Flagyl (metronidazole).
Some bacteria produce an enzyme called beta-lactamase. This enzyme inactivates Penicillins. Adding a beta-lactamase inhibitor, like clavulanic tart, prevents this inactivation.
Sumycin (tetracycline) is not effected by the beta-lactamases. It does, however, have some nasty side effects similar to sunburn (sun sensitivity), nail discoloration, muscle pain, difficult or painful swallowing, variation in the amount of urine and brown/gray tooth discoloration. Source(s): Pharmacist

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