An important example of the transfer of genes attached to a plasmid in bacteria e.g. Escherichia coli (E. coli) is the case of the so-called R or resistance factor. The R factor is a plasmid that carries, in addition to the fertility factor genes, a number of genes with resistance to different anti-bacterial drugs. The fertility factor enables genes to be passed on via a plasmid from one bacterium to another, immediately rendering the recipients and there progeny resulting in multiple gene resistance. In medical bacteriology R plasmids represent a serious threat to the control of pathogenic bacteria. Indiscriminating the use of antibiotics presenting a major cause in the spread of drug resistant bacterial strains.