Q: Explain why mutations for antibiotic resistance spread so rapidly among bacteria

Frequent use of antibiotic kills many bacteria, creating a selection pressure. As a result, bacteria with mutations that give them resistance to a particular antibiotic have an advantage over the other bacteria that do not. They survive to reproduce more than the other types, and pass on this advantageous allele in greater numbers. The frequency of this allele therefore increases in subsequent generations, leading to an increase in frequency of resistant types in subsequent generations. As bacteria have a haploid genome, this alleles will be expressed and there will be no masking of any recessive alleles. In addition, bacteria multiply rapidly as they reproduce asexually by forming clones.