The overuse of antibiotics may not be exclusively responsible for antibiotic resistance.

Research works to tackle antibiotic resistance

The overuse of antibiotics may not be exclusively responsible for antibiotic resistance, according to new research.

The study by the University of Basel found that bacteria can develop resistance to antibiotics from their competitors. Writing in Cell Reports, researchers show that some bacteria inject a toxic cocktail into their rivals leading to cell lysis and death.

Researchers also found that if the released material contains certain drug-resistant genes, the specific resistance can be bestowed upon the new owner. As such, the antibiotic is no longer effective and the bacteria can reproduce.

“Some of these toxic proteins kill the bacterial competition very effectively, but do not destroy the cells,” explained Professor Marek Basler, who led the research. “Others severely damage the cell envelope, which leads to less of the attacked bacteria and hence the release of its genetic material.”

In the study, the researchers analysed the drug-resistant bacterium Acinetobacter baumanni - a typical hospital germ that originated during the Iraq war. The bacteria is also known as the ‘Iraq bug’ because it was spread by American soldiers returning home from combat.

The team found that the emergence and spread of multidrug resistance could be attributed - amongst other things - to the skills of certain bacteria. First, the bacteria combat their rivals by injecting them with toxic proteins - or effectors - using the type VI secretion system (T6SS), a poison syringe. Second, they are able to uptake and reuse the released genetic material.

In the model Acinetobacter baylyi, a close relative of the Iraq bug, Professor Basler’s team identified five differently acting toxic effectors.

“For the bacteria it makes absolute sense to produce not only a single toxin, but a cocktail of various toxins with different effects,” Basler explains. “This increases the likelihood that the rival can be successful and in some cases also lysed to release their DNA.”

Professor Basler added that the T6SS 'can also be found in other pathogens such as those which cause pneumonia or cholera'.