New Canadian research is paving the way to a better understanding of strep infections, and may explain why some patients lose limbs to the bacteria, while others clear up with simple antibiotics.
Dr. Donald Low, a microbiologist at Mount Sinai Hospital in Toronto who took part in the research, says the bacteria they studied, Group A streptococcus, is the same family of bugs that can cause something as mild as strep throat as well as something as serious as necrotizing fasciitis, otherwise known as “flesh-eating disease.”
“That’s what’s so strange about this bacteria: sometimes it causes very mild disease that even without antibiotic treatment you can get over, and then other times it causes you to lose life and limb,” Low told CTV’s Canada AM Tuesday.
Low says researchers are now closer to understanding this group of bacteria after he and his team, along with researchers at the Ontario Provincial Public Health Laboratories, The Methodist Hospital Research Institute in Houston, and the Broad Institute in Boston sequenced the DNA of dozens of strep strains involved in three strep epidemics that occurred over 15 years in Ontario.
Infectious disease researchers have long sought to understand the molecular “architecture” of bacterial epidemics. The recent advent of DNA sequencing techniques has allowed them to do that, so that researchers can complete genome sequences rapidly.
Low and his fellow researchers were able to fully sequence the genome of 95 strains of the bacteria from the epidemics, as well as analyze “single nucleotide polymorphisms” – or small DNA differences -- in 344 strains.
They found that just a few differences in the structure of the bacteria’s DNA were all that was needed for a relatively benign strain to become a virulent strain.
“It hasn’t been seen with this group of bacteria before that one change in the DNA can turn off a whole faucet of toxins and virulence factors,” Low said.
“To realize that one small change is able to do that helps us better understand the bacteria and better able to maybe treat it in the future.”
They also found that strains from each epidemic were genetically different from one another, rather than simply re-emerging time after time.
Results of the research appears in a study published online this week in Proceedings of the National Academy of Sciences.
The research opens the door to answering longstanding questions in bacterial epidemics. With Group A Strep specifically, the hope is that researchers can now more effectively develop drugs to prevent the spread of strep epidemics, as well as more quickly and effectively diagnose and treat each infection.
“There’s so much we’ve learned about this bacteria in the last 10 or 15 years that we’re a lot further on in developing vaccines, better treatment modalities – or something that can modify the outcome in patients who develop serious disease from one of the dangerous strains,” Low said.
