A new proof-of-concept study focused on Staphylococcus aureus, a bacterium that can cause dangerous infections that are resistant to antibiotics. (Image credit: BSIP via Getty Images)
Bacterial “superbugs” can develop resistance to antibiotics when the germs actively infect humans. Now, new research suggests that treatments for these serious infections could be improved by tracking genetic changes as they occur in bacteria.
“Our study demonstrates for the first time that monitoring the evolution of bacteria in real time using genome sequencing can reveal the strategies that bacteria use to survive, giving clinicians the opportunity to stay ahead of the curve and tailor treatments to the specific strain,” said study co-author Dr Stefano Giulieri, a clinical researcher and infectious disease physician at the Doherty Institute in Melbourne, Australia.
The study, published in May in the journal Nature Communications, focused on Staphylococcus aureus. The bacteria is carried by about 30% of the population and often causes no harm, but if it grows and causes an infection, it can become resistant to antibiotics. When resistant to multiple antibiotics, such bacteria are considered dangerous superbugs.
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To successfully treat superbug infections, it is important to understand whether the infection is “persistent” or “recurrent.” A persistent infection is one in which the patient continues to test positive for bacteria after five or more days of treatment. A recurrent infection is one in which the patient initially responds to treatment but later tests positive for bacteria again, either the same strain or a new type. Understanding the type of infection can help the physician decide on the direction of treatment and the choice of medications.
To find out whether genetic analysis could help make these decisions, the researchers analyzed S. aureus samples from 11 patients whose antibiotic treatment had failed. The study included 60 different strains of the bacteria.
Using genetic analysis, the research team determined whether each patient's samples contained the same strains of bacteria or genetically different strains. They then tested for signs of adaptive evolution, or signs that microbes are acquiring properties that help them survive. Adaptive evolution allows bacteria to survive even in the presence of antibiotics.
About a third of the strains selected showed signs of adaptive evolution, particularly in genes previously associated with antibiotic resistance. This suggests that antibiotic therapy in patients should be switched to drugs to which the bacteria are not resistant.
But the question remained: would this information really be useful to doctors in treating superbug infections?
To conduct the study, the researchers developed a survey based on 11 patient cases, including descriptions with and without an evolution analysis. They recruited 25 infectious disease physicians from around the world to participate in the survey. After receiving the evolution report, 34% of physicians changed their initial antibiotic regimen recommendations, changing antibiotics and/or adjusting the duration of use of the same drug.
These results demonstrate that in real clinical practice, tracking the evolution of bacteria
Sourse: www.livescience.com
