Not only is the number of multiresistant strains of bacteria in hospitals is increasing, but new research shows that developing resistance may also increase their ability to reproduce.
Usually, the acquisition of new genes, such as those for antibiotic resistance, comes at a cost to the bacteria which is reflected in a reduction in their rate of cell division. But new research shows that when a mutation occurs in the chromosome of a bacterium that has already incorporated a resistance-carrying plasmid, the bacteria divide faster in 10 percent of the combinations tested. Bacteria that first acquire resistance to antibiotics through mutation of their chromosome, and then gain further resistance by insertion of plasmids, show reproduction rate increases in 32 percent of combinations.
According to Science Daily:
“In 2009, the same research groups showed, for the first time, the importance of interactions between random genes in determining antibiotic resistance in bacteria. This latest study takes their initial findings a step further, by demonstrating that this is a general phenomenon, and thus may help to predict how a bacterial population will evolve after receiving a plasmid that confers resistance to a certain antibiotic.”
In related news, studies are showing that aggressive drug treatment may also be leading to the growth of drug-resistant pathogens. For example, as a result of aggressive use, chloroquine is now useless as a treatment for malaria across most of Africa.