<b>Objectives</b><br/> To investigated whether the CTX-M-14 gene could be transferred from a clinical <i>Shigella sonnei</i> strain to commensal <i>Escherichia coli</i> strain in the gastroenteritis microbiome.<br/><b>Methods</b><br/> <i>E. coli</i> strains were isolated from 30 stool samples of <i>S. sonnei</i> infected students in a gastroenteritis outbreak in 2004 and were characterized by antibiotic resistance analysis, <i>in vitro</i> conjugation and <i>in vivo</i> transfer of CTX-M-14 gene and molecular assays.<br/><b>Results</b><br/> One strain of <i>Escherichia coli</i> that had high levels of resistance to cefotaxime was isolated from a patient infected with <i>S. sonnei</i>. Isoelectric focusing showed that the <i>E. coli</i> and <i>S. sonnei</i> strains produced a β-lactamase with an isoelectric point of 8.1. Moreover, polymerase chain reaction analysis indicated that both strains possessed the same DNA sequences for CTX-M-14. The results of <i>in vitro</i> and <i>in vivo</i> conjugation showed that the efficiency of CTX-M-14 transfer from <i>S. sonnei</i> to <i>E. coli</i> was similar to CTX-M-14 transfer between <i>E. coli</i> strains.<br/><b>Conclusion</b><br/> The data suggest that the acquisition of the extended-spectrum β-lactamases gene by pathogenic bacteria in the human intestinal tract to commensal microbiome bacteria can cause serious infectious diseases.