RyfA sRNA, an alternative to fight resistant bacteria

C. Dozois, INRS, CRIPA-FRQNT

A small regulatory RNA found in many problematic bacteria, including Escherichia coli, appears to be responsible for managing the response of these bacteria to environmental stresses. Professor Charles Dozois from Institut national de la recherche scientifique (INRS) and doctoral student Hicham Bessaiah see a promising avenue for more effective treatment of antibiotic-resistant bacteria. Their results have been published in the journal PLOS Pathogens.

INRS Professor Charles Dozois, specialist in microbiology and immunology, also explains the impact of this discovery on animal health and food safety during a podcast interview broadcast by the show L'Heure de pointe Acadie and available at this link (in French): https://ici.radio-canada.ca/ohdio/premiere/emissions/l-heure-de-pointe-acadie/episodes/552189/rattrapage-du-lundi-19-juillet-2021

In conducting their work, the researchers and their team observed that the elimination of this regulatory RNA sequence greatly reduced the capacity of an E. coli to cause urinary tract infections in a mouse model. These infections are among the world's most common, especially in women, but they are sometimes hard to treat due to antibiotic resistance.

E.coli, which nests in the intestine without causing infection, can sometimes reach the urinary tract, which has a more acidic and salty environment, which requires these bacteria to adapt in order to survive. The bacteria have to withstand the environmental stressors in order to cause a bladder infection. "Without the regulatory RNA, the bacteria is more sensitive to changes in the environment and loses its infectious capacity," explained the doctoral student.

Inhibiting the RNA sequence

The idea is to block the RNA and make the bacteria less infectious, especially in the case of chronic infection, which can lead to increased resistance to treatment. If the bacteria are less resistant to stress, it will be more vulnerable to the host's immune response. Regulation of the systems that make it virulent will also be disrupted.

"People with recurrent urinary tract infections take antibiotics regularly. This leads to resistance and limits treatment options, which is why it's important to find alternatives," explained Professor Dozois.

Food safety

The relationship between virulence and stress isn't unique to urinary tract infections. The regulatory RNA sequence studied by the researchers is also found in a number of other major pathogenic bacteria, including Salmonella, a bacterium responsible for foodborne infections. Given that the RNA seems to impact multiple functions, the research group is working to better understand the mechanisms of regulation before pursuing additional research on antibiotic-resistant strains of bacteria, and is already working on avian infectious strains of E. coli to potentially develop alternatives to antibiotics for poultry health. In veterinary public health, an important strategy aims to develop antibiotic-free farms exempt of certain bacteria such as Salmonella in order to improve food safety for eggs and poultry.