06 Aug 2008   |   News

Israeli scientists suggest new methods to kill bacteria

Research Lead

Researchers at the Hebrew University of Jerusalem have found new ways to kill dormant bacteria that increasingly are becoming resistant to antibiotics.

Sub-populations of some bacteria can avoid the effects of antibiotics by slowing down their metabolism, remaining dormant for days and waiting for the right opportunity to start reproducing again.

The researchers studied dormant bacteria and found two new ways to kill them, either by subjecting them to a fresh dose of nutrients combined with the antibiotic treatment, or by infecting dormant bacteria with phages, which are viruses that attack bacteria.

Bio-physicist Nathalie Balaban at the Hebrew University’s Racah Institute of Physics, working with Orit Gefen and Sivan Pearl, has shown that sub-populations of E. Coli resist antibiotics by reducing their metabolic rate.

However, the team discovered that protein production does occur in dormant bacteria, immediately after exiting the stationary phase. Dormant bacteria can be killed by exposing them to antibiotics during this phase. The researchers says this finding offers a potentially new way to tackle dormant bacteria, the main cause of failure of antibiotic treatments in diseases such as tuberculosis, which often require months or years of antibiotic treatment.

Also, the results challenge current views on bacterial dormancy and suggest an alternative model for the differentiation of normal bacterial cells into dormant ones.

Working with Professor Oppenheim from the Hebrew University-Hadassah Medical School, the team also studied the interaction between dormant bacteria and phages, to determine whether dormancy evolved as a protection mechanism against phage attack, thus allowing the bacteria to survive under stressful environments.

The team showed that the existence of dormant bacteria provides advantage when the population is attacked by lysogenic phages, which reside inside bacteria for some generations and only then multiply and attack. However, dormancy provided no protection when the bacteria were attacked by lytic phages that reproduce and kill immediately.

“These results might lead to new phage therapies for fighting infections that persist despite antibiotics,” said Balaban.

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