Question

An example of ongoing natural selection that dramatically affects humans is the evolution of drug-resistant strains of pathogenic bacteria that can proliferate very quickly. With that in mind, explain how the following statement is inaccurate. "Antibiotics have created drug resistance in MRSA."

Answer 1

The ability of bacteria to withstand the effects of antibiotics is termed as antibiotic resistance. Many bacterial pathogens that cause several diseases in human beings have evolved into muti-drug resistant forms due to the increased use of antibiotics. Some of them may become super resistant and will have increased virulence and transmissibility.

When a group of bacteria infests a person, the patient is treated with antibiotics. The drug kills most of the bacteria but a few having a mutated gene for drug resistance survive and such survivors pass on the gene to succeeding generations. This leads to the formation of a population of resistant varieties. Thus, antibiotic resistance evolves naturally via natural selection.

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacteria that is resistant to many antibiotics. It can considered as a “super bug” which is resistant to many widely used antibiotics like penicillin, methicillin etc.

The trait for drug resistance is not “created” in an organism, rather the trait is “selected” among those that was already present in the population. This means that the gene for drug resistance was already present in a few individuals which got selected and was passed on to subsequent generations. Hence, there was a genetic advantage in the case of MRSA and these strains were able to better survive and reproduce.

Therefore, we can say that the statement “antibiotics have created drug resistance in MRSA” is inaccurate.