Study shows how collective behavior of bacterial colonies may contribute to antibiotic resistance The bacterial equivalent of a traffic jam causes multilayered biofilms to form in the presence of antibiotics, shows a study published today in eLife. The study reveals how the collective behavior of bacterial colonies may contribute to the emergence of antibiotic resistance. These insights could pave the way to new approaches for treating bacterial infections that help thwart the emergence of resistance. Bacteria can acquire resistance to antibiotics through genetic mutations. But they can also defend themselves via collective behaviors such as joining together in a biofilm - a thin, slimy film made up of many bacteria that is less susceptible to antibiotics.