Wanted: A bacterium that will kill another

Streptococcus suis (S. suis) is a bacterial species that causes important economic losses in the porc industry. This species is made up of a group of closely related bacteria, with each relative called a strain. As a comparison, brother and sisters share a family name and are very similar genetically but have may some little differences, such as personality. Therefore, even though some S. suis are pathogenic and

cause disease, not all members of the S. suis family are disease-causing. Despite living in animals, some strains do not cause illness and the animals that carry these bacteria are healthy, the animals are called asymptomatic carriers. Some non-disease causing bacteria produce small proteins called bacteriocins that act similarly to antibiotics. A team of researchers at the CRIPA worked to identify and characterize three bacteriocins produced by these “good” or non-virulent S. suis strains.

Increasing resistance to antibiotics among several bacterial species is a concern for the World Health Organization and population as a whole. As a result, the research and development of molecules to replace or reinforce currently used antibiotics is of critical importance. The discovery of Drs. Daniel Grenier (Université Laval), Michel Frenette (Université Laval) and Marcelo Gottschalk (Université de Montréal) is, therefore, promising because the three bacteriocins called suicine 65, suicine 3908 and suicine 90-1330 produced by non-virulent S. suis strains kill pathogenic S. suis by making holes in their cell wall. These bacteriocins also target the cell wall of another bacterial family called Staphylococcus, which confirms their killing ability.

Before these newly described bacteriocins become available to the market, their efficacy must be tested during experimental piglet infections. Remarkably while working with these bacteriocins the research team had an addition observation: these bacteriocins appear to act synergistically with antibiotics and may eventually be used to improve the efficacy of existing antibiotic therapies used to treat S. suis infections.

Source : Les bactériocines : de nouvelles armes pour le contrôle des infections à Streptococcus suis chez le porc. MAPAQ PSIA 811326. Daniel Grenier, Michel Frenette, Marcelo Gottschalk.

To learn more:

1. Vaillancourt K, LeBel G, Frenette M, Fittipaldi N, Gottschalk M, Grenier D. 2015. Purification and characterization of suicin 65, a novel class I type B lantibiotic produced by Streptococcus suis. PLoS One 10(12): e145854.

2. Vaillancourt K, LeBel G, Frenette M, Gottschalk M, Grenier D. 2015. Suicin 3908, a new lantibiotic produced by a strain of Streptococcus suis serotype 2 isolated from a healthy carrier pig. PLoS One 10(2): e0117245.

3. LeBel G, Vaillancourt K, Frenette M, Gottschalk M, Grenier D. 2014. Suicin 90-1330 from a non-virulent strain of Streptococcus suis: a nisin-related lantibiotic active on Gram-positive swine pathogens. Appl Environ Microbiol 80: 5484-5492.

4. LeBel G, Piché F, Frenette M, Gottschalk M, Grenier D. 2013. Antimicrobial activity of nisin against the swine pathogen Streptococcus suis and synergistic interaction with antibiotics. Peptides 50: 19-23.