Influence of pH Treatments on Survival of Escherichia coli O157:H7 in Continuous Cultures of Rumen Contents

2003 ◽  
Vol 228 (4) ◽  
pp. 365-369 ◽  
Author(s):  
Brandolyn H. Thran ◽  
Hussein S. Hussein ◽  
Doug Redelman ◽  
George C.J. Fernandez
Keyword(s):  
Escherichia Coli ◽  
Dry Matter ◽  
Microbial Population ◽  
Competitive Exclusion ◽  
Rumen Fluid ◽  
Sampling Period ◽  
Escherichia Coli O157 ◽  
Adaptation Period ◽  
E Coli ◽  
Influence Of Ph

The pH (i.e., 5.5, 5.75, 6.0, 6.25, 6.5, 6.75, 7.0, and 7.25) effect on Escherichia coli O157:H7 in an artificial rumen model was investigated. Eight fermenters were inoculated with bovine rumen fluid and were supplied with a diet (75 g of dry matter daily in 12 equal portions [every 2 hr]) containing similar forage-to-concentrate ratio. After an adaptation period (i.e., 3 days for adjusting the rumen fluid [pH 6.2] microbial population to the test pH and 4 days for adjustment to the diet at the test pH), each fermenter was inoculated with 109 cells of E. coli O157:H7. Samples were collected hourly for 12 hr and every 2 hr for an additional 12 hr and were analyzed by flow cytometer. E. coli O157:H7 could not be quantified after 24 hr, and detection was only possible after enrichment. Because the pathogen could not be detected 5 days postinoculation (i.e., Day 13), the fermenters were reinoculated with E. coli O157:H7 on Days 17 and 22. E. coli O157:H7 numbers decreased from 106 to 104/ml of fermenter contents in a quadratic ( P < 0.05) fashion over the 24-hr sampling period, and the rate of reduction was slower ( P < 0.05) for pH 7.0 than for other pH treatments. Results suggested that E. coli O157:H7 population were decreased by competitive exclusion and were not affected by culture pH.

Isolation, Selection, and Characterization of Lactic Acid Bacteria for a Competitive Exclusion Product To Reduce Shedding of Escherichia coli O157:H7 in Cattle

2003 ◽  
Vol 66 (3) ◽  
pp. 355-363 ◽  
Author(s):  
M. M. BRASHEARS ◽  
D. JARONI ◽  
J. TRIMBLE
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Competitive Exclusion ◽  
Rumen Fluid ◽  
Significant Inhibition ◽  
Escherichia Coli O157 ◽  
16S Rrna Sequence ◽  
E Coli ◽  
Acid And Bile Tolerance

Lactic acid bacteria (LAB) were selected on the basis of characteristics indicating that they would be good candidates for a competitive exclusion product (CEP) that would inhibit Escherichia coli O157:H7 in the intestinal tract of live cattle. Fecal samples from cattle that were culture negative for E. coli O157:H7 were collected. LAB were isolated from cattle feces by repeated plating on deMan Rogosa Sharpe agar and lactobacillus selection agar. Six hundred eighty-six pure colonies were isolated, and an agar spot test was used to test each isolate for its inhibition of a four-strain mixture of E. coli O157:H7. Three hundred fifty-five isolates (52%) showed significant inhibition. Seventy-five isolates showing maximum inhibition were screened for acid and bile tolerance. Most isolates were tolerant of acid at pH levels of 2, 4, 5, and 7 and at bile levels of 0.05, 0.15, and 0.3% (oxgall) and were subsequently identified with the API system. Lactobacillus acidophilus, Lactobacillus fermentum, Lactobacillus delbreukii, Lactobacillus salivarius, Lactobacillus brevis, Lactobacillus cellobiosus, Leuconostoc spp., and Pediococcus acidilactici were the most commonly identified LAB. Nineteen strains were further tested for antibiotic resistance and inhibition of E. coli O157:H7 in manure and rumen fluid. Four of these 19 strains showed susceptibility to all of the antibiotics, 13 significantly reduced E. coli counts in manure, and 15 significantly reduced E. coli counts in rumen fluid (P &lt; 0.05) during at least one of the sampling periods. One of the strains, M35, was selected as the best candidate for a CEP. A 16S rRNA sequence analysis of M35 revealed its close homology to Lactobacillus crispatus. The CEP developed will be used in cattle-feeding trials.

In Vitro Inactivation of Escherichia coli O157:H7 in Bovine Rumen Fluid by Caprylic Acid

2004 ◽  
Vol 67 (5) ◽  
pp. 884-888 ◽  
Author(s):  
THIRUNAVUKKARASU ANNAMALAI ◽  
MANOJ KUMAR MOHAN NAIR ◽  
PATRICK MAREK ◽  
PRADEEP VASUDEVAN ◽  
DAVID SCHREIBER ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Caprylic Acid ◽  
Rumen Fluid ◽  
Bacterial Load ◽  
Anaerobic Bacteria ◽  
Inhibitory Effect ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Bovine Rumen

The antibacterial effect of caprylic acid (35 and 50 mM) on Escherichia coli O157:H7 and total anaerobic bacteria at 39° C in rumen fluid (pH 5.6 and 6.8) from 12 beef cattle was investigated. The treatments containing caprylic acid at both pHs significantly reduced (P &lt; 0.05) the population of E. coli O157:H7 compared with that in the control samples. At pH 5.6, both levels of caprylic acid killed E. coli O157:H7 rapidly, reducing the pathogen population to undetectable levels at 1 min of incubation (a more than 6.0-log CFU/ml reduction). In buffered rumen fluid at pH 6.8, 50 mM caprylic acid reduced the E. coli O157:H7 population to undetectable levels at 1 min of incubation, whereas 35 mM caprylic acid reduced the pathogen by approximately 3.0 and 5.0 log CFU/ml at 8 and 24 h of incubation, respectively. At both pHs, caprylic acid had a significantly lesser (P &lt; 0.05) and minimal inhibitory effect on the population of total anaerobic bacteria in rumen compared with that on E. coli O157:H7. At 24 h of incubation, caprylic acid (35 and 50 mM) reduced the population of total anaerobic bacteria by approximately 2.0 log CFU/ml at pH 5.6, whereas at pH 6.8, caprylic acid (35 mM) did not have any significant (P &gt; 0.05) inhibitory effect on total bacterial load. Results of this study revealed that caprylic acid was effective in inactivating E. coli O157:H7 in bovine rumen fluid, thereby justifying its potential as a preslaughter dietary supplement for reducing pathogen carriage in cattle.

Retention of Acid Tolerance and Acid Shock Responses of Escherichia coli O157:H7 and Non-O157:H7 Isolates

1997 ◽  
Vol 60 (12) ◽  
pp. 1478-1482 ◽  
Author(s):  
DONNA MAE GARREN ◽  
MARK A. HARRISON ◽  
SCOTT M. RUSSELL
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Acid Tolerance ◽  
Escherichia Coli O157 ◽  
Adaptation Period ◽  
E Coli ◽  
Acid Shock ◽  
Acidic Conditions ◽  
Temperature Levels ◽  
Over Time

Escherichia coli O157:H7 and non-O157:H7 survival due to induced acid tolerance or shock responses when exposed to lactic acid over time was studied. Induced acid tolerance or shock responses could allow pathogens, like E. coli O157:H7, to survive acidic conditions in foods during storage. Escherichia coli O157:H7 isolates 932 and E009 and a non-Ol57:H7 strain, 23716, were grown to stationary phase at 32°C and exposed to one of two treatments: acid shock or acid adaption. Acid-shocked cells were exposed to lactic acid at pH 3.5 or 4.0. Acid-adapted cells were exposed to pH 5.5 for an adaptation period and then exposed to an acid challenge of pH 3.5 or 4.0. Samples were incubated at either 25 or 32°C and survival of the isolates at 0, 3, 24, 48, 72, and 168 h (7 days), 336 h (14 days), and 504 h (21 days) was determined. All three isolates survived longer with larger populations at pH 4.0 and 25°C compared to the other treatments. In cases where a difference was observed in the two responses, acid-shocked cells had a higher survival rate (typically less than 2 logs) than acid-adapted cells in most cases. Isolate differences were observed at the two pH and temperature levels. Isolate 932 was the most resistant to the acidic conditions during the incubation period, E009 intermediate, and strain 23716 was the most sensitive.

Soil versus Pond Ash Surfacing of Feedlot Pens: Occurrence of Escherichia coli O157:H7 in Cattle and Persistence in Manure†

2010 ◽  
Vol 73 (7) ◽  
pp. 1269-1277 ◽  
Author(s):  
ELAINE D. BERRY ◽  
JAMES E. WELLS ◽  
TERRANCE M. ARTHUR ◽  
BRYAN L. WOODBURY ◽  
JOHN A. NIENABER ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Sampling Period ◽  
Escherichia Coli O157 ◽  
Surface Material ◽  
Beef Heifers ◽  
Pond Ash ◽  
E Coli ◽  
Cattle Feces ◽  
Naturally Occurring ◽  
Survival Differences

Reducing Escherichia coli O157:H7 in cattle and their manure is critical for reducing the risk for human foodborne and waterborne illness. The objective of this study was to evaluate the effects of soil and pond ash surfaces for feedlot pens on the prevalence, levels, and/or persistence of naturally occurring E. coli O157:H7 and total E. coli in cattle (feces and hides) and manure. Cattle (128 beef heifers) were sorted among 16 pens: 8 surfaced with soil and 8 surfaced with pond ash. The prevalence of E. coli O157:H7 in feces decreased (P &lt; 0.0001) during the study from 57.0% on day 0 to 3.9% on day 84 but did not differ (P ≥ 0.05) between cattle on soil and on pond ash pens at any sampling period. The prevalence of the pathogen on hides and in feedlot surface material (FSM) also decreased (P &lt; 0.0001), with no effect of soil or pond ash surface (P ≥ 0.05). Similarly, levels of E. coli in FSM did not differ (P ≥ 0.05) at any sampling period, and there were no clear trends for survival differences of E. coli O157:H7 or E. coli in FSM between pond ash and soil surfaces, although E. coli populations survived at 5.0 log CFU/g of FSM on the pen surfaces 6 weeks after the cattle were removed. These results indicate that housing cattle on pens surfaced with pond ash versus pens surfaced with soil does not affect E. coli O157:H7 in cattle or their manure.

Survival and Growth of Escherichia coli O157:H7 in Unpasteurized and Pasteurized Milk

1997 ◽  
Vol 60 (6) ◽  
pp. 610-613 ◽  
Author(s):  
GUODONG WANG ◽  
TONG ZHAO ◽  
MICHAEL P. DOYLE
Keyword(s):  
Escherichia Coli ◽  
Microbial Population ◽  
Antagonistic Activity ◽  
Escherichia Coli O157 ◽  
Pasteurized Milk ◽  
E Coli ◽  
Milk Samples ◽  
Unpasteurized Milk ◽  
Uremic Syndrome ◽  
Survival And Growth

Escherichia coli O157:H7, which causes hemorrhagic colitis and hemolytic uremic syndrome, has been responsible for several outbreaks associated with consumption of unpasteurized and improperly processed pasteurized milk, and yogurt. Studies were conducted to determine the survival and growth characteristics of this pathogen in unpasteurized milk and pasteurized milk (3.5% fat, 2% fat, skim) at 5,8, 15, and 22°C for up to 28 days. Two levels of inocula (103 and 105 CFU/ml) of a mixture of five nalidixic acid-resistant E. coli O157:H7 strains were used. E. coli O157:H7 did not grow at 5°C and decreased by 1.6 to 2.0 log CFU/ml in 28 days. Growth occurred at 8°C, with an approximately 1- to 2-log CFU/ml increase within the first 4 days. About a 3- to 5-log CFU/ml increase in E. coli O157:H7 populations was observed at 15°C within the first 3 days. In 3 pasteurized milk samples, E. coli O157:H7 continued to grow to populations of greater than 1.0 × 108 CFU/ml at day 7 and remained constant during the remainder of the incubation period. At 22°C, the pH decreased rapidly to less than 4.0 within 4 days and E. coli O157:H7 decreased to undetectable populations within 14 days. E. coli O157:H7 grew more slowly (P &lt; 0.01) in unpasteurized milk, which had a higher initial microbial population, than in pasteurized milks at 8, 15, or 22°C, likely because of antagonistic activity from preexisting bacteria. No significant differences (P&gt; 0.05) in survival or growth of E. coli O157:H7 were observed among the pasteurized milk samples, regardless of fat concentration, at all temperatures throughout the study. The data indicate that temperature abuse during shipping and handling can result in significant growth of E. coli O157:H7. Holding milk at ≤5°C is recommended to prevent growth of this pathogen.

scholarly journals Displacement of Escherichia coli O157:H7 from Rumen Medium Containing Prebiotic Sugars

2002 ◽  
Vol 68 (2) ◽  
pp. 519-524 ◽  
Author(s):  
Albane de Vaux ◽  
Mark Morrison ◽  
Robert W. Hutkins
Keyword(s):  
Escherichia Coli ◽  
Culture System ◽  
Rumen Fluid ◽  
Enteric Bacteria ◽  
Fermentation Medium ◽  
Escherichia Coli O157 ◽  
Anaerobic Culture ◽  
Fluid Medium ◽  
E Coli ◽  
Cell Densities

ABSTRACT A fed-batch, anaerobic culture system was developed to assess the behavior of Escherichia coli O157:H7 in a rumen-like environment. Fermentation medium consisted of either 50% (vol/vol) raw or sterile rumen fluid and 50% phosphate buffer. Additional rumen fluid was added twice per day, and samples were removed three times per day to simulate the exiting of digesta and microbes from the rumen environment under typical feeding regimens. With both types of medium, anaerobic and enteric bacteria reached 1010 and 104 cells/ml, respectively, and were maintained at these levels for at least 5 days. When a rifampin-resistant strain of E. coli O157:H7 was inoculated into medium containing raw rumen fluid, growth did not occur. In contrast, when this strain was added to sterile rumen fluid medium, cell densities increased from 106 to 109 CFU/ml within 24 h. Most strains of E. coli O157:H7 are unable to ferment sorbitol; therefore, we assessed whether the addition of sorbitol as the only added carbohydrate could be used to competitively exclude E. coli O157:H7 from the culture system. When inoculated into raw rumen broth containing 3 g of sorbitol per liter, E. coli O157:H7 was displaced within 72 h. The addition of other competitive sugars, such as l-arabinose, trehalose, and rhamnose, to rumen medium gave similar results. However, whenever E. coli O157:H7 was grown in sterile rumen broth containing sorbitol, sorbitol-positive mutants appeared. These results suggest that a robust population of commensal ruminal microflora is required to invoke competitive exclusion of E. coli O157:H7 by the addition of “nonfermentable” sugars and that this approach may be effective as a preharvest strategy for reducing carriage of E. coli O157:H7 in the rumen.

Persistence of Escherichia coli O157:H7 on Lettuce Plants following Spray Irrigation with Contaminated Water

2003 ◽  
Vol 66 (12) ◽  
pp. 2198-2202 ◽  
Author(s):  
ETHAN B. SOLOMON ◽  
HOAN-JEN PANG ◽  
KARL R. MATTHEWS
Keyword(s):  
Escherichia Coli ◽  
Irrigation Water ◽  
Sampling Period ◽  
Repeated Exposure ◽  
Human Consumption ◽  
Contaminated Water ◽  
Escherichia Coli O157 ◽  
Plant Leaves ◽  
E Coli ◽  
Spray Irrigation

Irrigation water collected at farms growing crops for human consumption was artificially contaminated with E. coli O157: H7 and used to irrigate lettuce plants. Plants in a growth chamber were spray irrigated either once or intermittently with water contaminated with 102 or 104 CFU of E. coli O157:H7 per ml and were then sampled over a 30-day period. Only plants exposed to 102 CFU/ml on day 1 did not harbor the pathogen at the end of the sampling period. All other treatments resulted in contaminated plants at harvest. Plants irrigated with 104 CFU/ml contained high levels (up to 5 log CFU/g) of the pathogen at harvest. The results obtained in this study underscore the assertion that spray irrigation (the application of water directly to plant leaves) is linked to the contamination of crops and suggest that repeated exposure increases the E. coli O157:H7 level on the plant.

Effects of Diet on Rumen Proliferation and Fecal Shedding of Escherichia coli O157:H7 in Calves

2000 ◽  
Vol 63 (12) ◽  
pp. 1630-1636 ◽  
Author(s):  
SUZANA TKALCIC ◽  
CATHY A. BROWN ◽  
BARRY G. HARMON ◽  
ANANT V. JAIN ◽  
ERIC P. O. MUELLER ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Fatty Acid ◽  
Volatile Fatty Acid ◽  
Rumen Fluid ◽  
Rapid Development ◽  
Acid Resistance ◽  
Escherichia Coli O157 ◽  
Fecal Shedding ◽  
E Coli ◽  
The Impact

Calves inoculated with Escherichia coli O157:H7 and fed either a high-roughage or high-concentrate diet were evaluated for rumen proliferation and fecal shedding of E. coli O157:H7. Calves fed the high-roughage diet had lower mean rumen volatile fatty acid concentrations and higher rumen pH values than did calves fed the high-concentrate diet. Despite these differences in rumen conditions, the calves fed the high-roughage diet did not have greater rumen populations of E. coli O157: H7 and did not exhibit increased or longer fecal shedding compared with the calves fed the high-concentrate diet. Two calves shedding the highest mean concentrations of E. coli O157:H7 were both fed the high-concentrate diet. There was a significant (P &lt; 0.05) positive correlation between fecal shedding and rumen volatile fatty acid concentration in calves fed a high-concentrate diet. The effects of diet on E. coli O157:H7 proliferation and acid resistance were investigated using an in vitro rumen fermentation system. Rumen fluid collected from steers fed a high-roughage diet, but not from steers fed a high-concentrate diet, supported the proliferation of E. coli O157:H7. Rumen fluid from steers fed a high-concentrate diet rapidly induced acid resistance in E. coli O157:H7. The impact of diet on fecal shedding of E. coli O157:H7 is still unclear and may depend on dietary effects on fermentation in the colon and on diet-induced changes in the resident microflora. However, rapid development of acid tolerance by E. coli O157:H7 in the rumens of calves fed high-concentrate diets, allowing larger populations to survive passage through the acidic abomasum to proliferate in the colon, may be one factor that influences fecal shedding in cattle on feed.

Acquisition of Antibiotic Resistance Plasmids by Enterohemorrhagic Escherichia coli O157:H7 within Rumen Fluid

2002 ◽  
Vol 65 (6) ◽  
pp. 1038-1040 ◽  
Author(s):  
SHAIKH MIZAN ◽  
MARGIE D. LEE ◽  
BARRY G. HARMON ◽  
SUZANA TKALCIC ◽  
JOHN J. MAURER
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Rumen Fluid ◽  
Antibiotic Resistance Genes ◽  
Luria Bertani ◽  
Coli Strain ◽  
Enterohemorrhagic Escherichia Coli ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
R Plasmids

The emergence of antibiotic resistance among important foodborne pathogens like Escherichia coli O157:H7 has become an important issue with regard to food safety. In contrast to the case for Salmonella, antibiotic resistance has been slow in its development in E. coli O157:H7 despite the presence of mobile antibiotic resistance genes in other E. coli organisms that inhabit the same animal host. We set out to determine if rumen fluid influences the transfer of plasmid-mediated, antibiotic resistance to E. coli O157:H7. A commensal E. coli strain from a dairy cow was transformed with conjugative R plasmids and served as the donor in matings with naladixic acid–resistant E. coli O157:H7. R plasmids were transferred from the donor E. coli strain to E. coli O157:H7 in both Luria-Bertani (LB) broth and rumen fluid. R plasmids were transferred at a higher frequency to E. coli O157:H7 during 6 h of incubation in rumen fluid at rates comparable to those in LB broth, indicating that conditions in rumen fluid favor the transfer of the plasmids to E. coli O157. This finding suggests that the cow's rumen is a favorable environment for the genetic exchange of plasmids between microflora and resident E. coli O157:H7 in the bovine host.

The Effect of Different Grain Diets on Fecal Shedding of Escherichia coli O157:H7 by Steers

2000 ◽  
Vol 63 (11) ◽  
pp. 1467-1474 ◽  
Author(s):  
S. J. BUCHKO ◽  
R. A. HOLLEY ◽  
W. O. OLSON ◽  
V. P. J. GANNON ◽  
D. M. VEIRA
Keyword(s):  
Escherichia Coli ◽  
Rumen Fluid ◽  
Experimental Period ◽  
Escherichia Coli O157 ◽  
Fecal Shedding ◽  
E Coli ◽  
Significant Difference ◽  
Whole Cottonseed ◽  
Fecal Ph ◽  
Culture Positive

Three groups of six yearling steers (three rumen fistulated plus three nonfistulated) fed one of three different grain diets (85% cracked corn, 15% whole cottonseed and 70% barley, or 85% barley) were inoculated with 1010 CFU of Escherichia coli O157:H7 strain 3081, and the presence of the inoculated strain was followed in the rumen fluid and feces for a 10-week period. E. coli O157:H7 was rapidly eliminated from the rumen of the animals on all three diets but persisted in the feces of some animals up to 67 days after inoculation, suggesting that the bovine hindgut is the site of E. coli O157:H7 persistence. A significant difference existed in the levels of E. coli O157:H7 shed by the animals among diets on days 5, 7, 49, and 63 after inoculation (P &lt; 0.05). No significant difference was found between the levels shed among diets on days 9 through 42 and on day 67 (P &gt; 0.05). The number of animals that were culture positive for E. coli O157:H7 strain 3081 during the 10-week period was significantly higher for the barley fed group (72 of 114 samplings) as opposed to the corn fed group (44 of 114 samplings) (P &lt; 0.005) and the cottonseed and barley fed group (57 of 114 samplings) (P &lt; 0.05). The fecal pH of the animals fed the corn diet was significantly lower (P &lt; 0.05) than the fecal pH of the animals fed the cottonseed and barley and barley diets, likely resulting in a less suitable environment for E. coli O157:H7 in the hindgut of the corn fed animals. E. coli O157:H7 strain 3081 was present in 3 of 30 (corn, 1 of 10; cottonseed, 1 of 10; barley, 1 of 10) animal drinking water samples, 3 of 30 (corn, 1 of 10; cottonseed, 0 of 10; barley, 2 of 10) water trough biofilm swabs, 5 of 30 (corn, 0 of 10; cottonseed, 2 of 10; barley, 3 of 10) feed samples, and 30 of 30 manure samples taken from the pens during the entire experimental period. Mouth swabs of the steers were also culture positive for E. coli O157:H7 strain 3081 in 30 of 180 samples (corn, 7 of 60; cottonseed, 4 of 60; barley, 19 of 60) taken during the 10-week period. Minimizing environmental dissemination of E. coli O157:H7 in conjunction with diet modification may reduce numbers of E. coli O157:H7–positive cattle.

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