Tracking bacterial virulence: global modulators as indicators
Researchers of the University of Barcelona (UB) and the Institute for Bioengineering of Catalonia (IBEC) together with their collaborators, have determined a new kind of indicators for bacterial virulence which can help detect and preventing infection outbreaks caused by Escherichia coli.
Researchers of the University of Barcelona (UB) and the Institute for Bioengineering of Catalonia (IBEC) together with their collaborators, have determined a new kind of indicators for bacterial virulence which can help detect and preventing infection outbreaks caused by Escherichia coli.
Most of the bacterial strains of the E. coli are naturally found in the human intestine and they are not risky for the human health, except for certain kinds of bacteria (pathogenic), some of which provoke food intoxication which can be mortal. One of these E.coli virulent strains, of O104: H4 serotype, caused an important infectious strain in Germany in 2011. It was associated to a high prevalence of the haemolytic uremic syndrome. It was a recent developed strain which brought the highest death rate ever caused by E. coli.
The kind of virulent E.coli like this one are classified among pathotypes, which are defined by a mix of virulent factors (molecules produced by the bacteria contributing to its pathogenicity), phenotype and clinical association. A great part of the E.coli pathotypes is already identified and are characterized thanks to the study of virulent genes distribution in isolated strains of the infected patients. However, the virulent phenotype is not strictly linked to each pathotype; one pathotype can be more or less virulent depending on the strain and serotype functions, showing different virulent factors.
In the article which was published today in Scientific Reports, the IBEC researchers, the University of Barcelona, the University of Santiago de Compostela, the Institute of Medical Microbiology and German Center for Infection Research (DZIF) studied the correlation among the presence of certain genes and the virulent phenotype of the E.coli pathogenic strains. The researchers found that genome of different E.coli enteroaggregative intestine pathogenic strains have two variables of the same gene which codifies for a global modulator (the hha gen). These variables, named hha2 and hha3, are common in the E.coli isolation of infected patients and produce Shiga toxins, like in the high virulent strain O104:H4. The hha2 and hha3 variables are also common in the E.coli strains of the ST131 type, which are resistant to antibiotics, cause extraintestinal infections and are worldwide distributed.
“We have shown that detecting these kinds of proteins and its genes can be a new strategy to identify the bacterial pathogenic serotypes” says Antonio Juárez from IBEC/UB, who led the study. “In the E.coli case, we are able to widen the hha2 and hha3 variables and establish them as indicators of the isolated E.coli virulent strains from the environment and the patients; we can easily detect the pathogenic variables in order to stop infection outbreaks in a better way.
Article of reference:
A. Prieto, I. Urcola, J. Blanco, G. Dahbi, M. T. Muniesa, P. Quirós, L. Falgenhauer, T. Chakraborty, M. Hüttener and A. Juárez (2016). “Tracking bacterial virulence: global modulators as indicators”. Science Reports, April 2016. Doi: 10.1038/srep25973