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New Hypothesis for Bacterial Resistance to Antibiotics

Non-resistant bugs acquire DNA from resistant ones (Mar. 7)

A researcher at the University of Granada has formulated a new hypothesis concerning a riddle that the scientific community has not been able to solve: Why are bacteria becoming increasingly more resistant to antibiotics?

According to Dr. Mohammed Bakkali, non-resistant bacteria develop resistance by ingesting the DNA of resistant organisms when they are stressed by the presence of antibiotics. “In this way,” Bakkali says, “the non-resistant bacteria become resistant completely by accident on ingesting this DNA and can even become much more virulent, partly due to the stress we subject them to when we [abuse the] use of antibiotics.”

For decades, scientists have been investigating when, how, and why bacteria take up DNA from other antibiotic-resistant organisms, but until now “nobody has pinpointed the reason why bacteria ingest this genetic material,” Bakkali says.

His findings were published in the Archives of Microbiology.

According to Bakkali, under normal conditions bacteria could have a lot to lose if they “decide” to take up DNA, since they do not have a “DNA reader” that would allow them to ingest only useful molecules rather than harmful ones.

In his article, Bakkali argues that bacteria do not look for DNA to ingest. In fact, they appear not to “want” the DNA from other bacteria, since they are constantly degrading it. DNA uptake appears to be a chance event and the sub-product of a type of bacterial motility that is part of a bacterium’s response to stress, Bakkali says.

Thus, the widespread misuse of antibiotics may not only be selecting for resistant strains, but may also be causing bacteria to take up more DNA, with a consequent increase in the chances of acquiring drug resistance and virulence, Bakkali concludes.

Sources: University of Granada; March 7, 2013; and Archives of Microbiology; February 5, 2013.

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