Atypical EnteropathogenicEscherichia coliSecretes Plasmid Encoded Toxin

Abstract

Plasmid encoded toxin (Pet) is a serine protease originally described in enteroaggregative Escherichia coli (EAEC) prototype strain 042 whose entire characterization was essentially obtained from studies performed with the purified toxin. Here we show that Pet is not exclusive to EAEC. Atypical enteropathogenic Escherichia coli (aEPEC) strains, isolated from diarrhea cases, express Pet and its detection in supernatants of infected HEp-2 cells coincides with the appearance of cell damage, which, in turn, were similar to those described with purified Pet. Pet secretion and the cytotoxic effects are time and culture medium dependent. In presence of DMEM supplemented with tryptone cell rounding and detachment were observed after just 5 h of incubation with the bacteria. In the absence of tryptone, the cytotoxic effects were detected only after 24 h of infection. We also show that, in addition to the prototype EAEC, other pet+ EAEC strains, also isolated from diarrhea cases, induce cellular damage in the same degree as the aEPEC. The cytotoxic effects of EAEC and aEPEC strains were significantly reduced in the presence of a serine protease inhibitor or anti-Pet IgG serum. Our results show a common aspect between the aEPEC and EAEC and provide the first evidence pointing to a role of Pet in aEPEC pathogenesis.

Alteraciones en el tracto urinario durante la infección con Proteus mirabilis que expresa la toxina codificada en plásmido (Pet)

“…Pet was described and studied for the first time as a cytotoxic protein produced by EAEC 042 (Eslava et al, 1998). A recent study of an atypical enteropathogenic E. coli clinical isolate also showed the expression of Pet (Ruiz et al, 2014). In this study, we corroborate the presence of Pet in P. mirabilis RTX339 (Pet+) strain through genotypic and phenotypic assays, as previously demonstrated by Gutiérrez et al, (2012).…”

Consuming fermented distillers' dried grains with solubles (DDGS) feed reveals a shift in the faecal microbiota of growing and fattening pigs using 454 pyrosequencing

“…Fermented DDGS feed inhibited the growth of potential pathogens, including E. coli, Dialister, P. copri and unclassified Enterobacteriaceae. Pigs are highly susceptible to enteric disorders and diseases (Ruiz et al 2014), which are predominantly attributed to E. coli. Although there is no direct evidence that Dialister causes infection in growing pigs, recent studies have discovered potential pathogenic Dialister in swine manure using 16S rRNA gene cloning and sequencing (Han et al 2011).…”

The serine protease Pic as a virulence factor of atypical enteropathogenicEscherichia coli

“…A few studies have shown that SPATE genes are present in EPEC, but production of the corresponding proteins has been demonstrated only for Pet. 22 Our data show that Pic is secreted by BA589 and displays the same biological activities of the prototype EAEC 042. 13 The production of some SPATEs, such Pic, shows maximal expression at 37 C in alkaline pH, 2 conditions employed in our study.…”

“…14 In general, tEPEC strains are more homogeneous in terms of virulence characteristics, while aEPEC strains often carry genes encoding virulence factors of other diarrheagenic E. coli (DEC) pathotypes. [18][19][20][21][22][23][24] Furthermore, phylogenetic studies indicate that aEPEC have a genetic background with characteristics that allow the acquisition, retention and expression of genes encoding virulence factors of other DEC pathotypes. 19,25 One example is the presence of SPATE-encoding genes in aEPEC, 18,22 which can confer adaptive advantages and additional pathogenic mechanisms to the A/E lesion.…”