MRSA enzyme could help tackle antibiotic tolerance timebomb

Scientists at the University of St Andrews will spend the next two years researching whether an enzyme found in MRSA bacteria from the 1950s could help solve today’s problem of antibiotic tolerance. 

Dr Jo Hobbs, from the School of Biology, and her team hope to unravel the mechanisms behind antibiotic tolerance so that the process can be avoided or reversed, and that antibiotics can remain effective. 

Antibiotic tolerance is a strategy bacteria use to survive treatment: they die more slowly, leading to persistent infections. 

It’s a stepping stone to antibiotic resistance, when bacteria can avoid being killed by antibiotics. 

The World Health Organisation has identified resistance to antibiotics as one of the top global threats to health: it already causes around five million deaths per year. 

Dr Jo Hobbs, a molecular microbiologist, said: “Antibiotic resistance gets a lot of attention, but tolerance is an underappreciated problem that must be tackled. 

“In the past 10 years, it’s become clear that bacteria become tolerant first, surviving longer in the presence of antibiotics. This can lead to recurring infections and the bacteria can then become resistant to treatment. 

“Tolerance is already a widespread phenomenon: it has been detected in more than 20 bacterial species, including streptococci, which cause pneumonia and strep throat, and Staphylococcus aureus, which is the SA part of MRSA.”

Isolating enzymes from 70-year-old MRSA 

Hobbs and her team want to understand how tolerance develops at the molecular level. 

They’re investigating a bacterial enzyme called Prs, which changes over time to confer tolerance. 

They found the mutated enzyme by examining one of the first samples of MRSA taken in the 1950s. 

“There are lots of different strains of MRSA, but we investigated this one from the 1950s because it’s very slow to grow in the lab compared to other strains. 

“This was a good clue, as the bacteria that exhibit antibiotic tolerance are often a bit slow. Growing slowly is one way that they get around antibiotics. 

“We isolated a special version of Prs from this ancient MRSA and over the next two years, we’ll be studying how its molecular structure has changed, and how this affects the response of bacteria to antibiotics. 

“We’ll also find out the impact of tolerance caused by Prs on different antibiotic treatments.” 

Hobbs says projects like this are essential to tackle a looming public health issue. 

“We need antibiotics to be effective, or we’ll return to a time when simple, common infections are deadly. 

“Antibiotic tolerance can lead to recurring serious infections – it’s vital we understand and tackle its underlying mechanisms.” 

Dr Jo Hobbs was awarded a £125,000 Springboard Award from the Academy of Medical Sciences and the Wellcome Trust.