Illustration showing mechanism of developing antibiotic multiresistance in bacteria. Bacteria pass on genes for antibiotic resistance to their offspring when they multiply (left). However horizontal gene transfer (HGT, dark blue) is the primary mechanism for the spread of antibiotic resistance in bacteria. In this process bacteria receive resistance genes through horizontal plasmid transfer, where plasmids (fragments of DNA - green circles) are acquired from other bacterial cells. This mechanism can produce bacterial strains resistance to multiple antimicrobial drugs.