Dataset Information

Strain differences in fitness of Escherichia coli O157:H7 to resist protozoan predation and survival in soil.

ABSTRACT: Escherichia coli O157:H7 (EcO157) associated with the 2006 spinach outbreak appears to have persisted as the organism was isolated, three months after the outbreak, from environmental samples in the produce production areas of the central coast of California. Survival in harsh environments may be linked to the inherent fitness characteristics of EcO157. This study evaluated the comparative fitness of outbreak-related clinical and environmental strains to resist protozoan predation and survive in soil from a spinach field in the general vicinity of isolation of strains genetically indistinguishable from the 2006 outbreak strains. Environmental strains from soil and feral pig feces survived longer (11 to 35 days for 90% decreases, D-value) with Vorticella microstoma and Colpoda aspera, isolated previously from dairy wastewater; these D-values correlated (P<0.05) negatively with protozoan growth. Similarly, strains from cow feces, feral pig feces, and bagged spinach survived significantly longer in soil compared to clinical isolates indistinguishable by 11-loci multi-locus variable-number tandem-repeat analysis. The curli-positive (C+) phenotype, a fitness trait linked with attachment in ruminant and human gut, decreased after exposure to protozoa, and in soils only C- cells remained after 7 days. The C+ phenotype correlated negatively with D-values of EcO157 exposed to soil (rs?=?-0.683; P?=?0.036), Vorticella (rs?=?-0.465; P?=?0.05) or Colpoda (rs?=?-0.750; P?=?0.0001). In contrast, protozoan growth correlated positively with C+ phenotype (Vorticella, rs?=?0.730, P?=?0.0004; Colpoda, rs?=?0.625, P?=?0.006) suggesting a preference for consumption of C+ cells, although they grew on C- strains also. We speculate that the C- phenotype is a selective trait for survival and possibly transport of the pathogen in soil and water environments.

SUBMITTER: Ravva SV

PROVIDER: S-EPMC4097067 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Strain differences in fitness of Escherichia coli O157:H7 to resist protozoan predation and survival in soil.

Ravva Subbarao V SV Sarreal Chester Z CZ Mandrell Robert E RE

PloS one 20140714 7

Escherichia coli O157:H7 (EcO157) associated with the 2006 spinach outbreak appears to have persisted as the organism was isolated, three months after the outbreak, from environmental samples in the produce production areas of the central coast of California. Survival in harsh environments may be linked to the inherent fitness characteristics of EcO157. This study evaluated the comparative fitness of outbreak-related clinical and environmental strains to resist protozoan predation and survive in ...[more]

PMID: 25019377

Similar Datasets

Project description:In this study, we determined the nucleotide sequence of the 5.4-kb SalI restriction fragment of the recombinant plasmid pEO40-1, cloned from the large plasmid of enterohemorrhagic Escherichia coli (EHEC) O157:H7 strain EDL 933. This revealed two open reading frames which shared approximately 60% homology to the hlyC and hlyA genes of the E. coli alpha-hemolysin (alpha-hly) operon. We termed these genes EHEC-hlyA and EHEC-hlyC to distinguish them from the alpha-hly genes. Preliminary sequence analysis indicated that another open reading frame homolog to the hlyB gene is located close to the 3' end of EHEC-hlyA. The predicted molecular masses of the EHEC-hlyA and EHEC-hlyC gene products were 107 and 19.9 kDa, respectively. The EHEC hemolysin protein (EHEC-Hly) was not secreted into the culture supernatant by the strain EDL 933. However, hemolytic activity was found in the broth culture supernatant after transforming EDL 933 with the recombinant plasmid pRSC6 carrying the hlyB and hlyD genes from the E. coli alpha-hemolysin operon. The EHEC hemolysin was precipitated and used as an antigen for immunoblot analysis. This demonstrated that 19 of 20 reconvalescent-phase serum samples from patients with hemolytic uremic syndrome reacted specifically with the antigen; conversely, only 1 of 20 control serum samples demonstrated reactivity. To investigate the prevalence of EHEC hemolysin genes in diarrheagenic E. coli, a PCR was developed to specifically detect EHEC-hlyA. All Shiga-like toxin-producing O157 strains and 12 of 25 Shiga-like toxin-producing non-O157 strains were PCR positive; strains of other categories of diarrheagenic E. coli were PCR negative. All PCR-positive strains hybridized with the CVD 419 probe. We found the CVD 419 probe to be identical to the 3.4-kb HindIII fragment of plasmid pEO40 carrying most of the EHEC-hlyA gene and a part of the putative EHEC-hlyB gene. In this study, the newly discovered EHEC hemolysin was shown to be responsible for the enterohemolytic phenotype and demonstrated to be related but not identical to alpha-hemolysin. The EHEC hemolysin appears to have clinical importance because it occurs in all O157 strains tested and is reactive to sera of patients with hemolytic uremic syndrome.

Dataset Information

Strain differences in fitness of Escherichia coli O157:H7 to resist protozoan predation and survival in soil.

Publications

Strain differences in fitness of Escherichia coli O157:H7 to resist protozoan predation and survival in soil.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure