Salt, alone or in combination with sucrose, can improve the survival of Escherichia coli O157 (SERL 2) in model acidic sauces

The commercial production of microbiologically safe and stable sauces containing acetic acid is guided by the Comité des Industries des Mayonnaises et Sauces Condimentaires de la Communauté Economique Européenne's (CIMSCEE) code. The CIMSCEE safety value is calculated using a linear regression equation combining weighted contributions of pH and aqueous-phase concentrations of undissociated acetic acid, NaCl, and sugars. By implication, the CIMSCEE safety equation predicts that increasing concentrations of hurdles will always increase inactivation of the target pathogen. In this study, the time to achieve a 3-log10 reduction of an acid-resistant, acid-adapted, Shiga toxin-producing Escherichia coli (STEC) O157 isolate was determined experimentally for 81 formulations at various pHs and acetic acid, NaCl, and sucrose concentrations in a broth model. The combinations were intended to simulate the aqueous phase of acidic sauces and dressings. Experimental data were fitted to the log logistic model to estimate the time to 3-log10 reduction (t3D). Comparison of fitted t3D estimates with CIMSCEE values showed agreement in predicting safety (as defined by CIMSCEE) for the majority of formulations. However, CIMSCEE safety predictions were "fail dangerous" for 13 of 81 formulations. Among these formulations and others, the observed E. coli t3D initially increased and then decreased with increasing osmolalities (NaCl and sucrose). Relative protection increased with exposure time where the protective effect of NaCl predominated. While commercial acidic sauces are not considered high-risk vehicles for STEC, interactions among hurdles that decrease their combined effectiveness are deserving of further investigation because they may reveal mechanisms of broader relevance in the inactivation of pathogens in foods.     

Survival of Escherichia coli O157 in abattoir waste products

AIMS: This study monitored survival and growth of Escherichia coli O157 in ovine and bovine abattoir waste. METHODS: Blood and gut contents were inoculated separately with cocktails of E. coli O157. Samples were stored aerophilically and microaerophilically at 5 degrees C, 15 degrees C and 30 degrees C to represent storage at different container depths and at extremes of UK ambient temperature. CONCLUSIONS: Results showed survival of E. coli O157 was irrespective of oxygen content with no significant differences observed between aerophilic and microaerophilic environments. Numbers of E. coli O157 in ovine and bovine gut contents showed no change when stored at 5 degrees C and increased 1-2 log(10) at 15 degrees C and 30 degrees C in 28 h. In ovine and bovine blood, irrespective of storage temperature, there was a 0.5-2 log(10) reduction or no change in numbers except in ovine blood stored at 30 degrees C where the fall in numbers was followed by a 3 log(10) increase. In aged (stored at 4 degrees C for 18 h before spiking) bovine blood there was no significant change in numbers at 5 degrees C while at 15 degrees C there was 2 log(10) rise after 48 h. At 30 degrees C there was an initial 1 log(10) decrease in numbers followed by a 1 log(10) rise over the following 40 h. SIGNIFICANCE AND IMPACT OF STUDY: Abattoir wastes may become contaminated from animals infected with Verocytotoxigenic E. coli O157 and in certain storage conditions these pathogens could significantly increase in numbers. There is need for care in abattoir waste disposal, not only for personnel subject to direct contact, but also in the prevention of cross contamination to adjacent land and water courses which could indirectly infect humans.     

Survival of verocytotoxigenic Escherichia coli O157 in soil, water and on surfaces

Cattle and sheep are major reservoirs of Escherichia coli O157 and consequently these and certain other farm animals can pass out large numbers of this organism in their faeces. Thus the ability of the organism to survive in faeces, on pastureland and in associated water systems has important implications for its spread to crops by direct application of manure, by irrigation with infected water or directly to man by contact with animals or contaminated soil. Model systems were used to determine the persistence of the organism in river water, cattle faeces, soil cores and on stainless steel work surfaces. Survival of the organism was found to be greatest in soil cores containing rooted grass. Under these conditions viable numbers were shown to decline from approximately 10(8) g(-1) soil to between 10(6) and 10(7) g(-1) soil after 130 d. When the organism was inoculated into cattle faeces it remained detectable at high levels for more than 50 d. In contrast the organism survived much less readily in cattle slurry and river water where it fell in numbers from more than 10(6) ml(-1) to undetectable levels in 10 and 27 d, respectively. The survival of E. coli O157 was also investigated on stainless steel surfaces, where as air-dried deposits, it was shown to survive for periods in excess of 60 d. It was most stable at chill temperatures (4 degrees C) and viability was only partially reduced at 18 degrees C. In addition to stainless steel, the organism was shown to survive for extended periods on domestic (plastic) cutting boards, both at room and chill temperatures. Sanitizing agents, such as hypochlorites and a compound comprising both cationic and anionic-based active ingredients were found to be effective in killing various VTEC on stainless steel surfaces.     

Biocontrol of Escherichia coli O157 with O157-Specific Bacteriophages

Escherichia coli O157 antigen-specific bacteriophages were isolated and tested to determine their ability to lyse laboratory cultures of Escherichia coli O157:H7. A total of 53 bovine or ovine fecal samples were enriched for phage, and 5 of these samples were found to contain lytic phages that grow on E. coli O157:H7. Three bacteriophages, designated KH1, KH4, and KH5, were evaluated. At 37 or 4°C, a mixture of these three O157-specific phages lysed all of the E. coli O157 cultures tested and none of the non-O157 E. coli or non-E. coli cultures tested. These results required culture aeration and a high multiplicity of infection. Without aeration, complete lysis of the bacterial cells occurred only after 5 days of incubation and only at 4°C. Phage infection and plaque formation were influenced by the nature of the host cell O157 lipopolysaccharide (LPS). Strains that did not express the O157 antigen or expressed a truncated LPS were not susceptible to plaque formation or lysis by phage. In addition, strains that expressed abundant mid-range-molecular-weight LPS did not support plaque formation but were lysed in liquid culture. Virulent O157 antigen-specific phages could play a role in biocontrol of E. coli O157:H7 in animals and fresh foods without compromising the viability of other normal flora or food quality.     

Long-Term Survival of Shiga Toxin-Producing Escherichia coli O26, O111, and O157 in Bovine Feces

Cattle are an important reservoir of Shiga toxin-producing Escherichia coli (STEC) O26, O111, and O157. The fate of these pathogens in bovine feces at 5, 15, and 25°C was examined. The feces of a cow naturally infected with STEC O26:H11 and two STEC-free cows were studied. STEC O26, O111, and O157 were inoculated into bovine feces at 10¹, 10³, and 10⁵ CFU/g. All three pathogens survived at 5 and 25°C for 1 to 4 weeks and at 15°C for 1 to 8 weeks when inoculated at the low concentration. On samples inoculated with the middle and high concentrations, O26, O111, and O157 survived at 25°C for 3 to 12 weeks, at 15°C for 1 to 18 weeks, and at 5°C for 2 to 14 weeks, respectively. Therefore, these pathogens can survive in feces for a long time, especially at 15°C. The surprising long-term survival of STEC O26, O111, and O157 in bovine feces shows that such feces are a potential vehicle for transmitting not only O157 but also O26 and O111 to cattle, food, and the environment. Appropriate handling of bovine feces is emphasized.     

Survival of Escherichia coli O157:H7 on cattle hides

The objective of this study was to determine the time period that Escherichia coli O157:H7 survives on the hides of cattle. Extensive research has been conducted and is ongoing to identify and develop novel preharvest intervention strategies to reduce the presence of E. coli O157:H7 on live cattle and subsequent transfer to processed carcasses. If a reduction of E. coli O157:H7 levels in feces can be achieved through preharvest intervention, it is not known how long it would take for such reductions to be seen on the hide. In the study presented herein, three trials were conducted to follow E. coli O157:H7 hide prevalence over time. For each trial, 36 animals were housed in individual stanchions to minimize or prevent hide contamination events. Through prevalence determination and isolate genotyping with pulsed-field gel electrophoresis, survival of E. coli O157:H7 on the hides of live cattle was determined to be short lived, with an approximate duration of 9 days or less. The results of this study suggest that any preharvest interventions that are to be administered at the end of the finishing period will achieve maximum effect in reducing E. coli O157:H7 levels on cattle hides if given 9 days before the cattle are presented for processing. However, it should be noted that interventions reducing pathogen shedding would also contribute to decreasing hide contamination through lowering the contamination load of the processing plant lairage environment, regardless of the time of application.     

Analysis of Escherichia coli O157:H7 Survival in Ovine or Bovine Manure and Manure Slurry

Farm animal manure or manure slurry may disseminate, transmit, or propagate Escherichia coli O157:H7. In this study, the survival and growth of E. coli O157:H7 in ovine or bovine feces under various experimental and environmental conditions were determined. A manure pile collected from experimentally inoculated sheep was incubated outside under fluctuating environmental conditions. E. coli O157:H7 survived in the manure for 21 months, and the concentrations of bacteria recovered ranged from <10² to 10⁶ CFU/g at different times over the course of the experiment. The DNA fingerprints of E. coli O157:H7 isolated at month 1 and month 12 were identical or very similar. A second E. coli O157:H7-positive ovine manure pile, which was periodically aerated by mixing, remained culture positive for 4 months. An E. coli O157:H7-positive bovine manure pile was culture positive for 47 days. In the laboratory, E. coli O157:H7 was inoculated into feces, untreated slurry, or treated slurry and incubated at −20, 4, 23, 37, 45, and 70°C. E. coli O157:H7 survived best in manure incubated without aeration at temperatures below 23°C, but it usually survived for shorter periods of time than it survived in manure held in the environment. The bacterium survived at least 100 days in bovine manure frozen at −20°C or in ovine manure incubated at 4 or 10°C for 100 days, but under all other conditions the length of time that it survived ranged from 24 h to 40 days. In addition, we found that the Shiga toxin type 1 and 2 genes in E. coli O157:H7 had little or no influence on bacterial survival in manure or manure slurry. The long-term survival of E. coli O157:H7 in manure emphasizes the need for appropriate farm waste management to curtail environmental spread of this bacterium. This study also highlights the difficulties in extrapolating laboratory data to on-farm conditions.     

Survival of Escherichia coli O157:H7 in Soils from Jiangsu Province,China

Escherichia coli O157:H7 (E. coli O157:H7) is recognized as a hazardous microorganism in the environment and for public health. The E. coli O157:H7 survival dynamics were investigated in 12 representative soils from Jiangsu Province, where the largest E. coli O157:H7 infection in China occurred. It was observed that E. coli O157:H7 declined rapidly in acidic soils (pH, 4.57 – 5.14) but slowly in neutral soils (pH, 6.51 – 7.39). The survival dynamics were well described by the Weibull model, with the calculated t_d value (survival time of the culturable E. coli O157:H7 needed to reach the detection limit of 100 CFU g⁻¹) from 4.57 days in an acidic soil (pH, 4.57) to 34.34 days in a neutral soil (pH, 6.77). Stepwise multiple regression analysis indicated that soil pH and soil organic carbon favored E. coli O157:H7 survival, while a high initial ratio of Gram-negative bacteria phospholipid fatty acids (PLFAs) to Gram-positive bacteria PLFAs, and high content of exchangeable potassium inhibited E. coli O157:H7 survival. Principal component analysis clearly showed that the survival profiles in soils with high pH were different from those with low pH.     

Survival of Escherichia coli O157:H7 in ruminal or fecal contents incubated with corn or wheat dried distillers' grains with solubles

Dried distillers' grain with solubles (DDGS) is a by-product of ethanol production, and its use as cattle feed has increased as a result of the expansion of the fuel ethanol industry. However, the inclusion of corn DDGS into feedlot diets may increase the shedding of Escherichia coli O157:H7. This study investigated whether corn or wheat DDGS at 2 concentrations (20% or 40% vs. 100% barley grain) affected the survival of E.?coli O157:H7 in incubations of ruminal digesta and feces. Neither the type nor the level of DDGS had any effect on fermentation or the survival of E. coli O157:H7 in ruminal digesta. However, there was a time by DDGS interaction (p?< 0.05), where the numbers of E.?coli O157:H7 in feces did not differ after 4 or 12?h of incubation but were greater after 24?h in both 40% wheat and 40% corn DDGS as compared with other treatments. Additionally, after 24?h, the numbers of E. coli O157:H7 were greater in fecal incubations with corn DDGS than with wheat DDGS (p?< 0.05). The differences in the numbers of E.?coli O157:H7 were not attributable to changes in pH or in concentrations of volatile fatty acids in the media. These results suggest that the inclusion of high levels of corn or wheat DDGS in feedlot diets of cattle may encourage the survival of E. coli O157:H7 in feces.     

Survival of Escherichia coli O157 in a soil protozoan: implications for disease

Intra-protozoal growth of bacterial pathogens has been associated with increased environmental survival, virulence and resistance to biocides and antibiotics. Using laboratory microcosms we have shown that Escherichia coli O157 survives and replicates in a common environmental protozoan, Acanthamoeba polyphaga. As protozoa are widely distributed in soils and effluents, they may constitute an important environmental reservoir for transmission of E. coli O157 and other pathogens.     

Survival of Escherichia coli O157:H7 in wastewater from dairy lagoons

AIM: To determine the survival of Escherichia coli O157:H7 in dairy wastewater from on-site holding lagoons equipped with or without circulating aerators. METHODS AND RESULTS: Survival was monitored in dairy lagoon microcosms equipped with or without scale-size circulators. Both laboratory strains of E. coli O157:H7 and an isolate of E. coli H7 from wastewater had poor survival rates and none proliferated in water from waste lagoons with or without circulators. Furthermore, the decline of E. coli O157:H7 was not enhanced in those microcosms equipped with circulators. Strain variation in survival was observed in both circulated and settling waters. The decline rate of E. coli O157:H7 Odwalla strain increased proportionately with the inoculum load. Escherichia coli failed to establish itself in wastewater even after four sequential inoculations simulating continuous faecal input into the lagoon. The native aerobic bacteria survived longer with a decimal reduction time of 21.3 days vs either introduced or native E. coli, which declined rapidly with decimal reduction time of 0.5-9.4 days. CONCLUSIONS: Escherichia coli O157:H7 failed to establish and proliferate in dairy wastewater microcosms equipped with or without circulating aerators. SIGNIFICANCE AND IMPACT OF THE STUDY: This study furthers our knowledge of pathogen survival in wastewater, and suggests that proper management of wastewater before its use in irrigation is essential to reduce pathogen transfer to crops.     

Survival of Escherichia coli O157:H7 in bottled natural mineral water

A non-verotoxin-producing isolate of Escherichia coli O157:H7 was inoculated at final concentrations of 10(3) or 10(6) ml-1 into natural non-carbonated mineral water (MW), sterile natural mineral water (SMW) and sterile distilled deionized water (SDDW) and stored at 15 degrees C for 10 weeks. Samples were examined every 7 d for the presence of E. coli O157:H7 using a resuscitative/selective agar procedure. The MW samples were also plated onto a non-selective agar, R2A, to enumerate E. coli O157:H7 and the autochthonous flora. There was a significant difference in the survival of E. coli O157:H7 (10(3) ml-1 inoculum) between the MW and the SDDW at time periods 0, 7, 14 (P < 0.005) 21, 28, 35 (P < 0.001) and 42 d (P < 0.05) and between the MW and the SMW at time periods 7, (P < 0.05) 14, 21 (P < 0.005) 28 (P < 0.01) and 35 d (P < 0.05), with the pathogen surviving longest in the MW samples. In contrast, at 10(6) ml-1, no significant differences in the survival of E. coli O157:H7 were observed between the water types. The presence of E. coli O157:H7 (10(3) ml-1) in the MW samples did not have an antagonistic effect on the recovery of the autochthonous flora. Transmission electron microscopy analysis demonstrated that the E. coli O157:H7 cells lyse during storage, releasing their contents into the surrounding environment. These substances may have been utilized by the autochthonous flora and thereby explain why the numbers of flora recovered from the inoculated MW samples were higher than those recovered from the uninoculated samples.     

Studies of Escherichia coli Cultured on RainbowTM Agar O157 with Particular Reference to Enterohaemorrhagic Escherichia coli (EHEC)

Rainbow^TM Agar O157 is designed for the rapid isolation and identification of enterohaemorrhagic Escherichia coli (EHEC), particularly O157, characterised by black colonies. Five-hundred-eighty-five E. coli strains, including O157, O111 and O113 serogroups from many sources were examined on Rainbow^TM Agar O157. EHEC O157 could readily be isolated and recognized uniquely by typical black colonies. Some other EHEC also stand out as blue-black, whereas O113 and some other EHEC strains were mauve, red or pink and indistinguishable from SLT-negative strains of E. coli.     

Survival of Escherichia coli O157 in faeces of experimentally infected rats and domestic pigeons

In order to evaluate the role of some synanthropic animals in the spreading of Escherichia coli O157, laboratory rats and domestic pigeons were experimentally infected per os with E. coli O157. Rats infected with 10(5) colony forming units (cfu) (n = 5) and 10(9) cfu (n = 5) shed E. coli O157 for 2 +/- 1.7 d and 9.8 +/- 1.3 d, respectively. In the faeces of infected rats stored at 4 degrees C in a moist environment, at 4 degrees C in a dry environment or at 20 degrees C in a moist environment, E. coli O157 survived for 34 weeks. When stored at 20 degrees C or - 20 degrees C in a dry environment, E. coli O157 survived for greater than or = 36 weeks. Pigeons infected with 10(5) cfu (n = 5) and 10(9) cfu (n = 5) shed the pathogen for 14.8 +/- 3.4 d and 20.2 +/- 5.2 d, respectively. Both species, rats and pigeons, can be important in spreading of the E. coli O157 infection in cattle.     

Characterization of an Escherichia coli O157:H7 Plasmid O157 Deletion Mutant and Its Survival and Persistence in Cattle

Escherichia coli O157:H7 causes hemorrhagic colitis and hemolytic-uremic syndrome in humans, and its major reservoir is healthy cattle. An F-like 92-kb plasmid, pO157, is found in most E. coli O157:H7 clinical isolates, and pO157 shares sequence similarities with plasmids present in other enterohemorrhagic E. coli serotypes. We compared wild-type (WT) E. coli O157:H7 and an isogenic ΔpO157 mutant for (i) growth rates and antibiotic susceptibilities, (ii) survival in environments with various acidity, salt, or heat conditions, (iii) protein expression, and (iv) survival and persistence in cattle following oral challenge. Growth, metabolic reactions, and antibiotic resistance of the ΔpO157 mutant were indistinguishable from those of its complement and the WT. However, in cell competition assays, the WT was more abundant than the ΔpO157 mutant. The ΔpO157 mutant was more resistant to acidic synthetic bovine gastric fluid and bile than the WT. In vivo, the ΔpO157 mutant survived passage through the bovine gastrointestinal tract better than the WT but, interestingly, did not colonize the bovine rectoanal junction mucosa as well as the WT. Many proteins were differentially expressed between the ΔpO157 mutant and the WT. Proteins from whole-cell lysates and membrane fractions of cell lysates were separated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional gel electrophoresis. Ten differentially expressed ~50-kDa proteins were identified by quadrupole-time of flight mass spectrometry and sequence matching with the peptide fragment database. Most of these proteins, including tryptophanase and glutamate decarboxylase isozymes, were related to survival under salvage conditions, and expression was increased by the deletion of pO157. This suggested that the genes on pO157 regulate some chromosomal genes.     

Structure of shiga toxin type 2 (Stx2) from Escherichia coli O157:H7

Several serotypes of Escherichia coli produce protein toxins closely related to Shiga toxin (Stx) from Shigella dysenteriae serotype 1. These Stx-producing E. coli cause outbreaks of hemorrhagic colitis and hemolytic uremic syndrome in humans, with the latter being more likely if the E. coli produce Stx2 than if they only produce Stx1. To investigate the differences among the Stxs, which are all AB(5) toxins, the crystal structure of Stx2 from E. coli O157:H7 was determined at 1.8-A resolution and compared with the known structure of Stx. Our major finding was that, in contrast to Stx, the active site of the A-subunit of Stx2 is accessible in the holotoxin, and a molecule of formic acid and a water molecule mimic the binding of the adenine base of the substrate. Further, the A-subunit adopts a different orientation with respect to the B-subunits in Stx2 than in Stx, due to interactions between the carboxyl termini of the B-subunits and neighboring regions of the A-subunit. Of the three types of receptor-binding sites in the B-pentamer, one has a different conformation in Stx2 than in Stx, and the carboxyl terminus of the A-subunit binds at another. Any of these structural differences might result in different mechanisms of action of the two toxins and the development of hemolytic uremic syndrome upon exposure to Stx2.     

Survival of Escherichia coli O157:H7 in Soils from Vegetable Fields with Different Cultivation Patterns

Escherichia coli O157:H7 survived longer in soils from plastic-greenhouse cultivation than soils from the open field. Soil pH, organic carbon levels, and the ratio of bacterial phospholipid fatty acids (PLFAs) to fungal PLFAs played the significant roles in survival of O157:H7. Greater attention should be paid to the control of pathogen contamination under conditions of plastic-greenhouse cultivation.     

Survival of Escherichia coli O157:H7 in feces from corn- and barley-fed steers

The survival of Escherichia coli O157:H7 in feces from steers fed corn (CO) or barley (BA) was evaluated at -10, +4 and +22 degrees C. Fecal pats were inoculated with a four-strain mixture of nalidixic-acid resistant E. coli O157:H7 at two levels: 10(3) CFU g(-1) (low, L) and 105 CFU g(-1) (high, H). At -10 degrees C, duration of survival of E. coli O157:H7 was reduced (p < 0.05) in CO-L (35 days) compared to BA-L (49 days), likely due to the effects of fecal volatile fatty acids in combination with a fecal pH of <6.5. At 4 degrees C, E. coli O157:H7 was detected in BA-H, CO-H, CO-L and BA-L for 77, 77, 56 and 63 days, respectively, with no difference (p > 0.05) observed in the duration of survival or rate of decline of E. coli O157:H7 among treatments. Survival of E. coli O157:H7 was twice as likely (p < 0.05) at 22 degrees C than at 4 degrees C and -10 degrees C. While pH and dry matter content increased, and volatile fatty acid concentrations decreased over 84 days at all three temperatures, these changes were most pronounced at 22 degrees C. Survival of E. coli O157:H7 for extended periods of time in feces from both corn- and barley-fed animals was demonstrated, thus fecal material may serve as a vector for the transmission of the organism. The greater survival of E. coli O157:H7 at 22 degrees C suggests that temperature may play a role in the seasonality of transmission and prevalence of this bacterium in feedlot cattle. The reported greater prevalence of E. coli O157:H7 in cattle fed barley as compared to those fed corn does not appear to be related to elevated risk of transmission arising from differential survival of the bacterium in feces.     

Survival and growth of Escherichia coli O157:H7 on salad vegetables.

The influence of modified-atmosphere packaging, storage temperature, and time on survival and growth of Escherichia coli O157:H7 inoculated onto shredded lettuce, sliced cucumber, and shredded carrot was determined. Growth of psychotrophic and mesophilic microorganisms and changes in pH and sensory qualities of vegetables, as judged by subjective evaluation, were also monitored. Packaging under an atmosphere containing 3% oxygen and 97% nitrogen had no apparent effect on populations of E. coli O157:H7, psychotrophs, or mesophiles. Populations of viable E. coli O157:H7 declined on vegetables stored at 5 degrees C and increased on vegetables stored at 12 and 21 degrees C for up to 14 days. The most rapid increases in populations of E. coli O157:H7 occurred on lettuce and cucumbers stored at 21 degrees C. These results suggest that an unknown factor(s) associated with carrots may inhibit the growth of E. coli O157:H7. The reduction in pH of vegetables was correlated with initial increases in populations of E. coli O157:H7 and naturally occurring microfloras. Eventual decreases in E. coli O157:H7 in some samples, e.g., those stored at 21 degrees C, are attributed to the toxic effect of accumulated acids. Changes in visual appearance of vegetables were not influenced substantially by growth of E. coli O157:H7. The ability of E. coli O157:H7 to growth on raw salad vegetables subjected to processing and storage conditions simulating those routinely used in commercial practice has been demonstrated.     

Survival of Escherichia coli O157:H7 in the rhizosphere of maize grown in waste-amended soil

AIMS: To assess whether the persistence of Escherichia coli O157:H7 in soil amended with cattle slurry and ovine stomach content waste is affected by the presence of a maize rhizosphere. METHODS AND RESULTS: Cattle slurry and ovine stomach content waste were inoculated with E. coli O157:H7. Wastes were then applied to soil cores with and without established maize plants. The pathogen survived in soil for over 5 weeks, although at significantly greater numbers in soil receiving stomach content waste in comparison to cattle slurry. Persistence of the pathogen in soil was unaffected by the presence of a rhizosphere. CONCLUSIONS: Other factors may be more influential in regulating E. coli O157:H7 persistence in waste-amended soil than the presence or absence of a rhizosphere; however, waste type did have significant affect on the survival of E. coli O157:H7 in such soil. SIGNIFICANCE AND IMPACT OF THE STUDY: Escherichia coli O157:H7 can be present within animal-derived organic wastes that are routinely spread on land. Introduced measures with regards to such waste disposal may decrease exposure to the organism; however, the persistence of E. coli O157:H7 for considerable periods in waste-amended soil may still pose some risk for both human and animal infection. This study has shown that whilst survival of E. coli O157:H7 in waste-amended soil is not significantly affected by the presence or absence of a maize rhizosphere; it may vary significantly with waste type. This may have implications for land and waste management.