Scientists discover hidden secrets of deadly Superbugs (19459000)
Acinetobacter Baumannii, an infamous tough bug found in hospitals for decades, was merely waiting and preparing to evolve into one of most dangerous “superbugs”.
Researchers at the University of East Anglia, along with partners from Canada and Mexico and the University of Toronto Scarborough, have now reconstructed its genetic history. The researchers’ pioneering work reveals how the pathogen reached global dominance not by a sudden, abrupt jump, but rather through a slow, steady advance.
The lead researcher, Dr Benjamin Evans of the Norwich Medical School at UEA explained: We know that the bacteria which cause infection in humans can become resistant to antibiotics that we treat with, making them ineffective. From the 1970s until today, we studied a particular bacterium called Acinetobacter Baumannii. The bacterium thrives particularly in hospitals and causes infections which are difficult to treat.
This is especially true for patients who are vulnerable.
The researchers found that bacteria evolved more resistance with each successive wave.
Our work shows how the antibiotic resistance that can build up gradually and suddenly shift the balance to the pathogen is one of the most clearest images yet. This superbug did not just suddenly appear. “It took decades to develop, and is still evolving.” Evans said.
Combining decades-old samples from hospitals with genome sequencing was the key to this breakthrough. The researchers gathered 226 samples from the 1970s and grew them on a lab bench.
They then sequenced the DNA of the samples using Oxford Nanopore Technology. The genomes of these samples were merged with those from more than 1,000 newer samples collected on six continents.
Researchers used high-performance computers to build a detailed evolutionary tree that showed how resistance genes developed over time in the bacteria as they appeared. The researchers reconstructed pathogens’ rise using genetic changes and the locations of samples collected.
Acinetobacter Baumannii was the most dominant lineage in 2005. When the bacteria acquired the two genetic components, oxa23 and the gene that confers antibiotic resistance, the tipping point was reached.
The pathogen was “supercharged”, making it harder to destroy.
Study also showed that there are at least four different groups of bacteria, with each group following its evolutionary course. The three evolved slowly, while a forth lineage developed independently. It is showing up more often in recent samples as a sign that a stronger variant may be on the rise.
Dr Evans stressed the importance of recognizing these changes. This work is important, because it is crucial to guide policies for how we will use antibiotics in the present and future. We need to find new ways to fight these bacteria, or infections may become intractable.
Dr Sadhana Singh, UKRI/BBSRC antimicrobial resistance lead, has added: This study shows that a hospital superbug has evolved slowly over the years, forming distinct drug-resistant subgroups and then spreading worldwide. This study shows how resistance to antimicrobials builds up over time and highlights the importance of understanding this change in order to stay ahead.
Antimicrobial resistance is a major problem in medical practice today.
According to the UEA research, pathogens such as Acinetobacter baumannii They don’t happen. Instead, they are built up gradually and quietly to a point where they tip the balance.
As Dr Evans put it: This superbug did not just suddenly appear. This superbug was developed over decades and is still evolving.
Journal Reference
- Matthew Neil, Frederic Grenier, Nancy Allard et al.
The evolution of Acinetobacter international clone 2, and its resistanceome, can be understood by examining new isolates dating from the 1970s through the early 2000s. Microbial Genomics. DOI: 10.1099/mgen.0.001752
