Tracking bacterial virulence: global modulators as indicators

‘Bad’ E. coli such as this one are classified into pathotypes, which are defined by a combination of virulence factors (molecules produced by the bacteria that contribute to its pathogenicity), phenotype, and clinical associations. A good deal is already known about pathogenic strains of E. coli thanks to knowing the distribution of virulence genes – the virulence phenotype – of clinical isolates. However, the virulence phenotype is not strictly associated to each pathotype; that is to say, it can vary according to strain and serotype.

In the paper published in Scientific Reports today, the researchers at IBEC, the UB, the Universidade de Santiago de Compostela and Germany’s Institute of Medical Microbiology and DZIF examined the correlation between the presence of certain genes and the virulence phenotype of highly pathogenic E. coli strains. The researchers found that the genomes of several intestinal pathogenic enteroaggregative E. coli strains harbour two variants of a gene that encodes a global modulator (the hha gene). These variants, termed hha2 and hha3, predominate in shiga toxin-producing isolates, such as the deadly O104:H4, as well as in the widely distributed and antibiotic resistant ST131 isolates, that cause extraintestinal infections.

“We show that tracking these proteins and their genes can be a new strategy to identify bacterial pathogenic serotypes,” says Antonio Juárez, UB professor and assocate researcher at IBEC, who led the study. “If we can amplify hha2 and hha3 as a virulence indicator in environmental and clinical E. coli isolates, this will help to easily track them and prevent outbreaks.”

Source article: Alejandro Prieto, Imanol Urcola, Jorge Blanco, Ghizlane Dahbi, Maria Teresa Muniesa, Pablo Quirós, Linda Falgenhauer, Trinad Chakraborty, Mário Hüttener and Antonio Juárez (2016). Tracking bacterial virulence: global modulators as indicators. Sci Rep 6, Article number: 25973

IBEC in the media:
La Vanguardia, “Un nuevo marcador de virulencia bacteriana puede prevenir brotes infecciosos”