EEF1A2 and gastroenteritis: However, the lack of detection of stn gene in most of the strains associated with gastroenteritis (data from the CNRVC), the presence and expression of hlyA genes in strains isolated from patients without extraintestinal infection (Ottaviani et al. 2009, and data from the CNRVC) and its widespread occurrence among environmental strains, suggest that there are additional virulence factors.