Why is penicillin not as effective as it was fifty years ago?

Answer 1

This isn't entirely true. Penicillin is still as effective against the bacteria that it combated 50 years ago, but new strains of penicillin resistant bacteria have evolved since 50 years ago. This means that penicillin is less effective against a larger percentage of bacteria than it was 50 years ago, solely because of the new, anti-biotic resistant strains.

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Answer 2

The anti-biotic Penicillin , once a panacea , is no longer as effective as it once was because of mutated strains of bacteria now resistant to the anti-biotic .

Answer 3

Because bacteria have evolved resistance to antibiotics.