Strain differences in fitness of Escherichia coli O157:H7 to resist protozoan predation and survival in soil.
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 li...
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2014-01-01
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| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC4097067?pdf=render |
| _version_ | 1818231815068975104 |
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| author | Subbarao V Ravva Chester Z Sarreal Robert E Mandrell |
| author_facet | Subbarao V Ravva Chester Z Sarreal Robert E Mandrell |
| author_sort | Subbarao V Ravva |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-12-12T10:56:23Z |
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| id | doaj.art-e5b6ea5da5db4721b604a6fd584826d5 |
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| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-12T10:56:23Z |
| publishDate | 2014-01-01 |
| publisher | Public Library of Science (PLoS) |
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| spelling | doaj.art-e5b6ea5da5db4721b604a6fd584826d52022-12-22T00:26:38ZengPublic Library of Science (PLoS)PLoS ONE1932-62032014-01-0197e10241210.1371/journal.pone.0102412Strain differences in fitness of Escherichia coli O157:H7 to resist protozoan predation and survival in soil.Subbarao V RavvaChester Z SarrealRobert E MandrellEscherichia 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.http://europepmc.org/articles/PMC4097067?pdf=render |
| spellingShingle | Subbarao V Ravva Chester Z Sarreal Robert E Mandrell Strain differences in fitness of Escherichia coli O157:H7 to resist protozoan predation and survival in soil. PLoS ONE |
| title | Strain differences in fitness of Escherichia coli O157:H7 to resist protozoan predation and survival in soil. |
| title_full | Strain differences in fitness of Escherichia coli O157:H7 to resist protozoan predation and survival in soil. |
| title_fullStr | Strain differences in fitness of Escherichia coli O157:H7 to resist protozoan predation and survival in soil. |
| title_full_unstemmed | Strain differences in fitness of Escherichia coli O157:H7 to resist protozoan predation and survival in soil. |
| title_short | Strain differences in fitness of Escherichia coli O157:H7 to resist protozoan predation and survival in soil. |
| title_sort | strain differences in fitness of escherichia coli o157 h7 to resist protozoan predation and survival in soil |
| url | http://europepmc.org/articles/PMC4097067?pdf=render |
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