Prevalence percentage of virulence-associated genes in A+B1 commensal (grey bars) and B2+D virulent (black bars) E. coli groups. Data are expressed as percentage (number of positive clones/number of total analysed clones). *Significant difference at P < 0.05 by applying the Fisher's exact test.
Sánchez et al. BMC Gastroenterology 2008 8:50 doi:10.1186/1471-230X-8-50