The researchers from Imperial College London say that the "alarm clock" is common among various types of bacteria, such as Salmonella and E. coli. Their discovery could explain why some people suffer repeated bouts of infections, like ear or urinary tract infections, even though they take antibiotics. The team aims to use these findings to look into "hard-to-treat infections."
Dr. Sophie Helaine, the lead author of the research from the Department of Medicine at Imperial, said, "Whenever bacteria such as Salmonella invade the body, around a third of the bugs 'cloak' themselves as a defence mechanism against the body's immune system. They enter a type of stand-by mode possibly to hide from the body's immune system, that means they are not killed by antibiotics. The bacteria stop replicating and can remain in this dormant state for days, weeks or even months. When the immune system attack has passed, some bacterial cells spring back to life and trigger another infection."
Dr. Helaine continued, "This is why, for instance, a woman may think she has recovered from a urinary tract infection – and yet days or weeks later it seems to return. Many patients may assume it's a different infection – but actually it's the same bug." (Related: Boosting immune system with natural methods offers many health benefits.)
She adds that these so-called persistent bacteria also "fuel antibiotic resistance," and this is why patients end up taking many courses of antibiotics for one infection. Taking this amount of antibiotics means that some bacteria are "developing resistance."
Earlier research from Dr. Helaine's lab determined that Salmonella bacteria go into stand-by mode by "poisoning" themselves using toxins.
In the current study, the team showed a mechanism that Salmonella use "to detoxify themselves." This wakes them from stand-by and lets them start growing again.
Dr. Helaine said it is possible that many bacteria use this same toxin, called TacT, to "switch into stand-by mode." These bacteria include those that cause many intestinal, ear, throat, or urinary tract infections and even tuberculosis.
Dr. Helaine shares that if they can determine how to control this particular mechanism and "force the bacteria out of stand-by" they can then be treated with antibiotics, effectively killing them.
For the study, Dr. Helaine et al. used Salmonella cells in the laboratory to identify the bacterial alarm clock. The team tested a collection of over 4,000 proteins to look for those that wake the bacteria up. They isolated an enzyme called peptidyl-tRNA hydrolase (Pth) that was an effective alarm clock.