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Title: Persistence of Escherichia coli O157 and non-O157 strains in agricultural soils

Author
item MA, JINCAI - University Of California
item Ibekwe, Abasiofiok - Mark
item CROWLEY, DAVID - University Of California
item YANG, CHING-HONG - University Of Wisconsin

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2014
Publication Date: 6/5/2014
Citation: Ma, J., Ibekwe, A.M., Crowley, D.E., Yang, C. 2014. Persistence of Escherichia coli O157 and non-O157 strains in agricultural soils. Science of the Total Environment. 490:822-829.

Interpretive Summary: Shiga toxin producing Escherichia coli O157 is one of the most important recently emerged foodborne pathogens. They can produce serious human illness linked to the consumption of contaminated food, mainly of cattle origin or associated with their byproducts. Recently, a substantial and a growing proportion of illnesses are caused by infections due to non-O157, and accumulating evidence has shown that fresh produce serves an important vehicle for the transmission of this pathogen. In this study, survival of E. coli O157:H7 and non O157 in 32 soils (16 organic, 16 conventional) from California (CA) and Arizona (AZ) was investigated. Our data showed that the non-pathogenic E. coli O157 survived longer than the pathogenic E. coli O157 while two non-O157 that are pathogenic survived much longer than E. coli O157. Our data suggest that the use of non pathogenic E. coli O157 to predict the survival behavior of the pathogenic strains may not present the most accurate results in most instances. The results of this research will be used by growers, researchers, FSIS, FDA, and different state agencies that are involved in leafy green production.

Technical Abstract: Shiga toxin producing Escherichia coli O157 and non-O157 serogroups are known to cause serious diseases in human. However, research on the persistence of E. coli non-O157 serogroups in preharvest environment is limited. In the current study, we compared the survival behavior of E. coli O157 to that of non-O157 E. coli strains in agricultural soils collected from three major fresh produce growing areas of California (CA) and Arizona (AZ). Results showed that the nonpathogenic E. coli O157:H7 4554 survived longer than the pathogenic E. coli O157:H7 EDL933 in Imperial Valley CA and Yuma AZ, but not in soils from the Salinas area. However, E. coli O157:NM was found to persist significantly longer than E. coli O157:H7 EDL933 in all soil tested from the three regions. Furthermore, two non-O157 (E. coli O26:H21 and E. coli O103:H2) survived significantly longer than E. coli O157:H7 EDL933 in all soils tested. Pearson correlation analysis showed that survival of the E. coli strains was affected by different environmental factors. Our data suggest that survival of E. coli O157 and non-O157 may be strain and soil specific, and therefore, care must be taken in data interpretation with respect to survival of this pathogen in different soils.