Understanding the role of bacteriophage resistance in shaping Salmonella populations

Understanding the role of bacteriophage resistance in shaping Salmonella populations

It has been discovered by researchers at the Quadram Institute and the University of East Anglia how resistance has facilitated the spread of virulent Salmonella variants. Some bacteria and viruses have developed resistance to antibiotics and bacteriophages, which might provide them a temporary survival advantage.

New strategies to tackle disease-causing germs are being sought as antibiotic resistance rises.

Researchers are exploring viruses as a potential source of information to fight bacteria. Some viruses can only multiply by attaching to bacteria, and there are more of them on Earth than there are stars in the galaxy. Because they are effective at eliminating their bacterial hosts, bacteriophages might become one of the new tools in the battle against bacterial illnesses.

Salmonella bacteria play an important factor in the spread of illness over the world. Salmonella entericaserovar Typhimurium (S. Typhimurium) is a member of the Salmonella genus that causes sickness in humans and animals and is responsible for 78 million annual cases of illness worldwide.

The ability of Salmonella Typhimurium to undergo genetic changes and hence overcome resistance is largely responsible for the bacteria’s widespread success. As a result, related strains come and go in waves, dominating for about a decade before being replaced by others. It’s like attempting to strike a moving target to create new treatments to combat these strains, as they may be more resistant to previous attempts of controlling them.

Researchers led by Professor Rob Kingsley of the Quadram Institute and the University of East Anglia have been investigating the genome of Salmonella to learn more about the bacteria’s resilience and how mutations in the genetic code have given certain strains an advantage. For instance, research from 2021 showed how Salmonella finds its niche in the pig industry.

Now, in a new study published in Microbial Genomics, researchers have examined the impact of bacteriophage resistance on Salmonella populations in the wild and how this predator-prey relationship has co-evolved through time.

In addition to preying on bacteria, bacteriophages may also aid in the transfer of genetic material across different bacterial species, making the interaction between them rather complicated. The reason for this is because phages can play a role in a process known as phage-mediated transduction, which facilitates the spread of genetic variety and the transmission of resistance genes across bacterial populations.

Like antibiotics, the clue to understanding the possible development of resistance to phage therapy is in how resistance develops in nature. The researchers said that there is a resurging interest in the use of phages as a substitute or as an accompaniment to antibiotic treatment for bacterial infections.

Researchers analyzed entire genome sequences of strains acquired from human and animal illnesses over the past few decades in collaboration with the UK Health Security Agency (UKHSA) and the Animal & Plant Health Agency (APHA).

They discovered that Salmonella strains that are particularly well-adapted to life in animals are also the kinds most likely to cause sickness in people. This bacterium’s phage-resistance seems to have aided its ability to colonize novel ecosystems.

Current dominant strain ST34 is not only resistant to numerous medications, but also displays increased resistance to bacteriophage infection compared to its predecessors. This is likely attributable to the organism having acquired phage genetic material into its genome, a move that conferred upon it a higher level of resistance to bacteriophage attack.

However, this creates a fascinating paradox since bacteria that have developed resistance to phages are less likely to acquire new genetic material via phage-mediated transduction, which might include resistance genes. Could the temporary benefit of phage resistance result in the permanent loss of adaptability, rendering bacteria vulnerable to social interventions and perhaps novel antimicrobial treatments? Data from surveillance reveals this might pave the way for the formation of a new clone that would eventually replace the existing one.

Genomic monitoring of these bacteria and their bacteriophages is essential to detect and respond to any new dangers, no matter what the circumstances. The researchers have a greater chance of mitigating the risks posed to human health by these bacteria if we understand how they co-evolve.

Sources:

Oliver J. Charity et al. (2022). Increased phage resistance through lysogenic conversion accompanying emergence of monophasic Salmonella Typhimurium ST34 pandemic strain, Microbial Genomics. DOI: 10.1099/mgen.0.000897

https://phys.org/news/2022-11-bacteriophage-resistance-salmonella-populations.html