Resumo

Introduction. The enteropathogenic Escherichia coli (EPEC) pathotype is subdivided into typical EPEC (tEPEC), which carries the EPEC adherence factor plasmid, and atypical EPEC (aEPEC), which lacks this plasmid. SPATEs (Serine Protease Autotransporters of Enterobacteriaceae) have been divided into two sub-groups based upon phylogenic criteria. One group includes SPATEs that display cytotoxic activity (EspC, EspP, Pet, Sat and SigA) and, the other group includes SPATEs that do not have demonstrated cytopathic activity on cells (EatA, EpeA, EspI, Pic, SepA, Tsh and Vat). In this study, we investigated the prevalence of these SPATEs sequences and their association with diarrhea in aEPEC strains and compared them with those of tEPEC strains. Materials & Methods. A total of 223 EPEC (70 typical and 153 atypical) strains isolated from 169 diarrheic and 54 nondiarrheic children in different cities of Brazil were examined for the presence of SPATEs sequences by PCR, and for cytotoxic activity by the HeLa adhesion assay. Results. The espC and sepA genes were found in both EPEC groups in similar frequencies (5.15.7% and 0.61.4%, respectively). The espP, pet, sat and vat genes were only found in aEPEC strains in frequencies between 1.3% and 9.1%. The tsh and sigA genes were not detected. None of the SPATEs genes were associated with diarrhea, but espC, espP and pet were more frequently found in aEPEC isolates from patients compared with isolates from controls. Considering the comparative frequencies between tEPEC and aEPEC, espI and pic genes were significantly more frequent in aEPEC than in tEPEC strains (9.1% vs 0%, and 7.8% vs 0%, P < 0.05). Fifteen EPEC (10 typical and 5 atypical) caused the detachment of the HeLa cell monolayer from the glass coverslip when tested in the adhesion assay, and did not present any of the SPATEs sequences tested. Conclusion. Our data indicate that specific SPATEs sequences are associated with aEPEC strains compared to tEPEC. Further studies are underway to elucidate the cell detachment caused by EPEC strains.