scholarly journals Environmental inactivation and irrigation-mediated regrowth of Escherichia coli O157:H7 on romaine lettuce when inoculated in a fecal slurry matrix

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6591 ◽  
Author(s):  
Jennifer A. Chase ◽  
Melissa L. Partyka ◽  
Ronald F. Bond ◽  
Edward R. Atwill
Keyword(s):  
Escherichia Coli ◽  
Field Trials ◽  
Inactivation Rate ◽  
Bacterial Inactivation ◽  
Romaine Lettuce ◽  
E Coli ◽  
Log Reduction ◽  
Salinas Valley ◽  
Kinetics Of ◽  
Insight Into

Field trials were conducted in July–August and October 2012 to quantify the inactivation rate of Escherichia coli O157:H7 when mixed with fecal slurry and applied to romaine lettuce leaves. Lettuce was grown under commercial conditions in Salinas Valley, California. One-half milliliter of rabbit, chicken, or pig fecal slurry, containing an average of 4.05 × 107 CFU E. coli O157:H7 (C0), was inoculated onto the upper (adaxial) surface of a lower leaf on 288 heads of lettuce per trial immediately following a 2.5 h irrigation event. To estimate the bacterial inactivation rate as a function of time, fecal matrix, irrigation and seasonal climate effects, sets of lettuce heads (n = 28) were sampled each day over 10 days and the concentration of E. coli O157:H7 (Ct) determined. E. coli O157:H7 was detected on 100% of heads during the 10-day duration, with concentrations ranging from ≤340 MPN/head (∼5-log reduction) to >3.45 × 1012 MPN/head (∼5-log growth). Relative to C0, on day 10 (Ct = 12) we observed an overall 2.6-log and 3.2-log mean reduction of E. coli O157:H7 in July and October, respectively. However, we observed relative maximum concentrations due to bacterial growth on day 6 (maximum Ct = 8) apparently stimulated by foliar irrigation on day 5. From this maximum there was a mean 5.3-log and 5.1-log reduction by day 10 (Ct = 12) for the July and October trials, respectively. This study provides insight into the inactivation and growth kinetics of E. coli O157:H7 on romaine lettuce leaves under natural field conditions. This study provides evidence that harvesting within 24 h post irrigation has the potential to increase the concentration of E. coli O157:H7 contamination, if present on heads of romaine lettuce; foliar irrigation can temporarily stimulate substantial regrowth of E. coli O157:H7.

Inactivation of Escherichia coli O157:H7 on Romaine Lettuce When Inoculated in a Fecal Slurry Matrix

2017 ◽  
Vol 80 (5) ◽  
pp. 792-798 ◽  
Author(s):  
Jennifer A. Chase ◽  
Edward R. Atwill ◽  
Melissa L. Partyka ◽  
Ronald F. Bond ◽  
David Oryang
Keyword(s):  
Escherichia Coli ◽  
Most Probable Number ◽  
Escherichia Coli O157 ◽  
Romaine Lettuce ◽  
Probable Number ◽  
Inoculum Concentration ◽  
E Coli ◽  
Log Reduction ◽  
Salinas Valley ◽  
Sampling Event

ABSTRACT A field trial was conducted in July 2011 to quantify the inactivation rate of Escherichia coli O157:H7 when mixed with fecal slurry and applied to romaine lettuce leaves. Lettuce was grown under commercial conditions in Salinas Valley, CA. One-half milliliter of rabbit fecal slurry, containing 6.3 × 107 CFU of E. coli O157:H7, was inoculated onto the upper (adaxial) surface of a lower leaf on 240 heads of lettuce within 30 min after a 2.5-h irrigation event. Forty-eight romaine lettuce heads were collected per event at 2.5 h (day 0.1), 19.75 h (day 0.8), 43.25 h (day 1.8), 67.25 h (day 2.8), and 91.75 h (day 3.8) postinoculation and were analyzed for the concentration of E. coli O157:H7 (Ct). E. coli O157:H7 was detected on 100% of collected heads in concentrations ranging from 340 to 3.40 × 1010 most probable number (MPN) per head. Enumeration data indicate substantial growth of E. coli O157:H7 postinoculation (2.5 h), leading to elevated concentrations, 1 to 3 log above the starting inoculum concentration (Co). By the end of the 92-h trial, we observed a net 0.8-log mean reduction of E. coli O157:H7 compared with Co; however, after accounting for the substantial bacterial growth, there was an overall 2.3-log reduction by the final sampling event (92 h). On the basis of two different regression models that used either the raw data for Ct or log-transformed values of Ct/Co during the period 2.5 to 91.75 h postinoculation, there was an estimated 76 to 80% reduction per day in bacterial counts; however, more accurate predictions of MPN per head of lettuce were generated by using non–log-transformed values of Ct. This study provides insight into the survival of E. coli O157:H7 transferred via splash from a contaminated fecal source onto produce during irrigation. Moreover, these findings can help generate inactivation times following a potential contamination incident.

Inactivation of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella in Cranberry, Lemon, and Lime Juice Concentrates

2003 ◽  
Vol 66 (9) ◽  
pp. 1637-1641 ◽  
Author(s):  
MARA C. L. NOGUEIRA ◽  
OMAR A. OYARZÁBAL ◽  
DAVID E. GOMBAS
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Pathogenic Bacteria ◽  
Antimicrobial Properties ◽  
Escherichia Coli O157 ◽  
Bacterial Inactivation ◽  
Lime Juice ◽  
E Coli ◽  
Log Reduction ◽  
C 32

The production of thermally concentrated fruit juices uses temperatures high enough to achieve at least a 5-log reduction of pathogenic bacteria that can occur in raw juice. However, the transportation and storage of concentrates at low temperatures prior to final packaging is a common practice in the juice industry and introduces a potential risk for postconcentration contamination with pathogenic bacteria. The present study was undertaken to evaluate the likelihood of Escherichia coli O157: H7, Listeria monocytogenes and Salmonella surviving in cranberry, lemon, and lime juice concentrates at or above temperatures commonly used for transportation or storage of these concentrates. This study demonstrates that cranberry, lemon, and lime juice concentrates possess intrinsic antimicrobial properties that will eliminate these bacterial pathogens in the event of postconcentration recontamination. Bacterial inactivation was demonstrated under all conditions; at least 5-log Salmonella inactivation was consistently demonstrated at −23°C (−10°F), at least 5-log E. coli O157:H7 inactivation was consistently demonstrated at −11°C (12°F), and at least 5-log L. monocytogenes inactivation was consistently demonstrated at 0°C (32°F).

Transfer of Escherichia coli O157:H7 from Simulated Wildlife Scat onto Romaine Lettuce during Foliar Irrigation

2015 ◽  
Vol 78 (2) ◽  
pp. 240-247 ◽  
Author(s):  
EDWARD R. ATWILL ◽  
JENNIFER A. CHASE ◽  
DAVID ORYANG ◽  
RONALD F. BOND ◽  
STEVEN T. KOIKE ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacterial Contamination ◽  
Assessment Model ◽  
Escherichia Coli O157 ◽  
Romaine Lettuce ◽  
E Coli ◽  
Weighted Arithmetic ◽  
Salinas Valley ◽  
Mean Concentration ◽  
Rabbit Feces

A field trial in Salinas Valley, California, was conducted during July 2011 to quantify the microbial load that transfers from wildlife feces onto nearby lettuce during foliar irrigation. Romaine lettuce was grown using standard commercial practices and irrigated using an impact sprinkler design. Five grams of rabbit feces was spiked with 1.29 × 108 CFU of Escherichia coli O157:H7 and placed −3, −2, and −1 days and immediately before a 2-h irrigation event. Immediately after irrigation, 168 heads of lettuce ranging from ca. 23 to 69 cm (from 9 to 27 in.) from the fecal deposits were collected, and the concentration of E. coli O157:H7 was determined. Thirty-eight percent of the collected lettuce heads had detectable E. coli O157:H7, ranging from 1 MPN to 2.30 × 105 MPN per head and a mean concentration of 7.37 × 103 MPN per head. Based on this weighted arithmetic mean concentration of 7.37 × 103 MPN of bacteria per positive head, only 0.00573% of the original 5 g of scat with its mean load of 1.29 × 108 CFU was transferred to the positive heads of lettuce. Bacterial contamination was limited to the outer leaves of lettuce. In addition, factors associated with the transfer of E. coli O157:H7 from scat to lettuce were distance between the scat and lettuce, age of scat before irrigation, and mean distance between scat and the irrigation sprinkler heads. This study quantified the transfer coefficient between scat and adjacent heads of lettuce as a function of irrigation. The data can be used to populate a quantitative produce risk assessment model for E. coli O157:H7 in romaine lettuce to inform risk management and food safety policies.

scholarly journals Inactivation of particle-associated Escherichia coli with chlorine dioxide

2016 ◽  
Vol 17 (1) ◽  
pp. 151-160 ◽  
Author(s):  
Tao Lin ◽  
Bingwei Hou ◽  
Zhe Wang ◽  
Wei Chen
Keyword(s):  
Escherichia Coli ◽  
Chlorine Dioxide ◽  
Inactivation Rate ◽  
Inactivation Kinetics ◽  
Strong Temperature Dependence ◽  
E Coli ◽  
Inactivation Rate Constant ◽  
Effects Of Ph ◽  
Inactivation Efficiency ◽  
Kinetics Of

In this paper, the inactivation of both free Escherichia coli (FE) and particle-associated E. coli (PAE) with chlorine dioxide (ClO2) were investigated using granular activated carbon effluent water samples. The inactivation rate of FE was higher than that of PAE and the reactivation ratio of PAE was higher than that of FE, indicating the threat of particle-associated bacteria. Response surface methodology (RSM) was applied to determine the factors influencing the disinfection efficiency of ClO2 in inactivating PAE. The experimental results indicated that particle concentration was a principal factor influencing the PAE inactivation efficiency, presenting a negative correlation, while exposure time and ClO2 dosage revealed a positive correlation. The inactivation kinetics of PAE using ClO2 was also investigated and the results demonstrated that PAE inactivation with ClO2 fitted the Chick–Watson kinetic model. The inactivation rate constants of PAE were found to follow the Arrhenius expression with an activation energy of 107.5 kJ/mol, indicating a relatively strong temperature dependence. However, there are minor effects of pH and initial ClO2 dosage on PAE inactivation rate constant.

scholarly journals Inactivation of Escherichia coli O157:H7 in Simulated Human Gastric Fluid

2005 ◽  
Vol 71 (1) ◽  
pp. 320-325 ◽  
Author(s):  
Mark L. Tamplin
Keyword(s):  
Escherichia Coli ◽  
Shigella Flexneri ◽  
Survival Rates ◽  
Gastric Fluid ◽  
Inactivation Rate ◽  
Host Susceptibility ◽  
E Coli ◽  
Average Survival ◽  
The Matrix ◽  
Kinetics Of

ABSTRACT Human disease caused by Escherichia coli O157:H7 is a function of the number of cells that are present at potential sites of infection and host susceptibility. Such infectious doses are a result, in part, of the quantity of cells that are ingested and that survive human host defenses, such as the low-pH environment of the stomach. To more fully understand the kinetics of E. coli O157:H7 survival in gastric fluid, individual E. coli O157:H7 strains were suspended in various media (i.e., saline, cooked ground beef [CGB], and CGB containing a commercial antacid product [CGB+A]), mixed at various proportions with simulated human gastric fluid (SGF), and then incubated at 37�C for up to 4 h. The highest inactivation rate among nine E. coli O157:H7 strains was observed in saline. Specifically, the average survival rates in 100:1 and 10:1 proportions of SGF-saline were −1.344 � 0.564 and −0.997 � 0.388 log10 CFU/h, respectively. In contrast, the average inactivation rate for 10 E. coli O157:H7 strains suspended in 10:1 SGF-CGB was −0.081 � 0.068, a rate that was 12-fold lower than that observed for SGF-saline. In comparison, the average inactivation rate for Shigella flexneri strain 5348 in 100:1 and 10:1 SGF-saline was −8.784 and −17.310, respectively. These latter inactivation rates were 7- to 17-fold higher than those for E. coli O157:H7 strains in SGF-saline and were 4-fold higher than those for E. coli O157:H7 strains in SGF-CGB. The survival rate of E. coli O157:H7 strain GFP80EC increased as the dose of antacid increased from one-half to twice the prescribed dose. A similar trend was observed for the matrix pH over the range of pH 1.6 to 5.7, indicating that pH is a primary factor affecting E. coli O157:H7 survival in SGF-CGB+A. These results can be used in risk assessment to define dose-response relationships for E. coli O157:H7 and to evaluate potential surrogate organisms.

Reduction of Escherichia coli O157:H7 Counts on Whole Fresh Apples by Treatment with Sanitizers

2000 ◽  
Vol 63 (6) ◽  
pp. 703-708 ◽  
Author(s):  
MARCY A. WISNIEWSKY ◽  
BONITA A. GLATZ ◽  
MARK L. GLEASON ◽  
CHERYLL A. REITMEIER
Keyword(s):  
Escherichia Coli ◽  
Chlorine Dioxide ◽  
Phosphate Buffer ◽  
Phosphate Buffer Solution ◽  
Escherichia Coli O157 ◽  
Peroxyacetic Acid ◽  
Water Control ◽  
Buffer Solution ◽  
E Coli ◽  
Log Reduction

The objectives of this study were to determine if washing of whole apples with solutions of three different sanitizers (peroxyacetic acid, chlorine dioxide, or a chlorine-phosphate buffer solution) could reduce a contaminating nonpathogenic Escherichia coli O157:H7 population by 5 logs and at what sanitizer concentration and wash time such a reduction could be achieved. Sanitizers were tested at 1, 2, 4, 8, and 16 times the manufacturer's recommended concentration at wash times of 5, 10, and 15 min. Whole, sound Braeburn apples were inoculated with approximately 1 × 108 or 7 × 106 CFU per apple, stored for 24 h, then washed with sterile water (control) or with sanitizers for the prescribed time. Recovered bacteria were enumerated on trypticase soy agar. Washing with water alone reduced the recoverable population by almost 2 logs from the starting population; this can be attributed to physical removal of organisms from the apple surface. No sanitizer, when used at the recommended concentration, reduced the recovered E. coli population by 5 logs under the test conditions. The most effective sanitizer, peroxyacetic acid, achieved a 5-log reduction when used at 2.1 to 14 times its recommended concentration, depending on the length of the wash time. The chlorine-phosphate buffer solution reduced the population by 5 logs when used at 3 to 15 times its recommended concentration, depending on wash time. At no concentration or wash time tested did chlorine dioxide achieve the 5-log reduction.

Inactivation of Escherichia coli O157:H7, Salmonella enterica Serotype Enteritidis, and Listeria monocytogenes on Lettuce by Hydrogen Peroxide and Lactic Acid and by Hydrogen Peroxide with Mild Heat

2002 ◽  
Vol 65 (8) ◽  
pp. 1215-1220 ◽  
Author(s):  
CHIA-MIN LIN ◽  
SARAH S. MOON ◽  
MICHAEL P. DOYLE ◽  
KAY H. McWATTERS
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Salmonella Enteritidis ◽  
Sensory Characteristics ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Log Reduction

Iceberg lettuce is a major component in vegetable salad and has been associated with many outbreaks of foodborne illnesses. In this study, several combinations of lactic acid and hydrogen peroxide were tested to obtain effective antibacterial activity without adverse effects on sensory characteristics. A five-strain mixture of Escherichia coli O157:H7, Salmonella enterica serotype Enteritidis, and Listeria monocytogenes was inoculated separately onto fresh-cut lettuce leaves, which were later treated with 1.5% lactic acid plus 1.5% hydrogen peroxide (H2O2) at 40°C for 15 min, 1.5% lactic acid plus 2% H2O2 at 22°C for 5 min, and 2% H2O2 at 50°C for 60 or 90 s. Control lettuce leaves were treated with deionized water under the same conditions. A 4-log reduction was obtained for lettuce treated with the combinations of lactic acid and H2O2 for E. coli O157:H7 and Salmonella Enteritidis, and a 3-log reduction was obtained for L. monocytogenes. However, the sensory characteristics of lettuce were compromised by these treatments. The treatment of lettuce leaves with 2% H2O2 at 50°C was effective not only in reducing pathogenic bacteria but also in maintaining good sensory quality for up to 15 days. A ≤4-log reduction of E. coli O157:H7 and Salmonella Enteritidis was achieved with the 2% H2O2 treatment, whereas a 3-log reduction of L. monocytogenes was obtained. There was no significant difference (P > 0.05) between pathogen population reductions obtained with 2% H2O2 with 60- and 90-s exposure times. Hydrogen peroxide residue was undetectable (the minimum level of sensitivity was 2 ppm) on lettuce surfaces after the treated lettuce was rinsed with cold water and centrifuged with a salad spinner. Hence, the treatment of lettuce with 2% H2O2 at 50°C for 60 s is effective in initially reducing substantial populations of foodborne pathogens and maintaining high product quality.

scholarly journals Effects of Essential Oils on Escherichia coli Inactivation in Cheese as Described by Meta-Regression Modelling

Foods ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 716
Author(s):  
Beatriz Nunes Silva ◽  
Vasco Cadavez ◽  
José António Teixeira ◽  
Ursula Gonzales-Barron
Keyword(s):  
Escherichia Coli ◽  
Essential Oils ◽  
Meta Analysis ◽  
Inhibitory Effects ◽  
Food Preservatives ◽  
E Coli ◽  
Log Reduction ◽  
Bactericidal Properties ◽  
Study Characteristics ◽  
Meta Regression

The growing intention to replace chemical food preservatives with plant-based antimicrobials that pose lower risks to human health has produced numerous studies describing the bactericidal properties of biopreservatives such as essential oils (EOs) in a variety of products, including cheese. This study aimed to perform a meta-analysis of literature data that could summarize the inactivation of Escherichia coli in cheese achieved by added EOs; and compare its inhibitory effectiveness by application method, antimicrobial concentration, and specific antimicrobials. After a systematic review, 362 observations on log reduction data and study characteristics were extracted from 16 studies. The meta-regression model suggested that pathogenic E. coli is more resistant to EO action than the non-pathogenic type (p < 0.0001), although in both cases the higher the EO dose, the greater the mean log reduction achieved (p < 0.0001). It also showed that, among the factual application methods, EOs’ incorporation in films render a steadier inactivation (p < 0.0001) than when directly applied to milk or smeared on cheese surface. Lemon balm, sage, shallot, and anise EOs showed the best inhibitory outcomes against the pathogen. The model also revealed the inadequacy of inoculating antimicrobials in cheese purposely grated for performing challenge studies, as this non-realistic application overestimates (p < 0.0001) the inhibitory effects of EOs.

scholarly journals Inactivation of Multi-Drug Resistant Non-Typhoidal Salmonella and Wild-Type Escherichia coli STEC Using Organic Acids: A Potential Alternative to the Food Industry

Pathogens ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 849
Author(s):  
Vinicius Silva Castro ◽  
Yhan da Silva Mutz ◽  
Denes Kaic Alves Rosario ◽  
Adelino Cunha-Neto ◽  
Eduardo Eustáquio de Souza Figueiredo ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Acetic Acid ◽  
Organic Acids ◽  
Sodium Hypochlorite ◽  
Bacterial Species ◽  
Disk Diffusion ◽  
Clinical Strains ◽  
Linear Pattern ◽  
E Coli ◽  
Log Reduction

Salmonella and Escherichia coli are the main bacterial species involved in food outbreaks worldwide. Recent reports showed that chemical sanitizers commonly used to control these pathogens could induce antibiotic resistance. Therefore, this study aimed to describe the efficiency of chemical sanitizers and organic acids when inactivating wild and clinical strains of Salmonella and E. coli, targeting a 4-log reduction. To achieve this goal, three methods were applied. (i) Disk-diffusion challenge for organic acids. (ii) Determination of MIC for two acids (acetic and lactic), as well as two sanitizers (quaternary compound and sodium hypochlorite). (iii) The development of inactivation models from the previously defined concentrations. In disk-diffusion, the results indicated that wild strains have higher resistance potential when compared to clinical strains. Regarding the models, quaternary ammonium and lactic acid showed a linear pattern of inactivation, while sodium hypochlorite had a linear pattern with tail dispersion, and acetic acid has Weibull dispersion to E. coli. The concentration to 4-log reduction differed from Salmonella and E. coli in acetic acid and sodium hypochlorite. The use of organic acids is an alternative method for antimicrobial control. Our study indicates the levels of organic acids and sanitizers to be used in the inactivation of emerging foodborne pathogens.

scholarly journals Using a Chemical Genetic Screen to Enhance Our Understanding of the Antimicrobial Properties of Gallium against Escherichia coli

Genes ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 34 ◽  
Author(s):  
Natalie Gugala ◽  
Kate Chatfield-Reed ◽  
Raymond J. Turner ◽  
Gordon Chua
Keyword(s):  
Escherichia Coli ◽  
Cell Envelope ◽  
Antimicrobial Properties ◽  
Iron Sulfur Cluster ◽  
Nucleotide Biosynthesis ◽  
E Coli ◽  
Chemical Genetic ◽  
Iron Sulfur ◽  
Insight Into ◽  
Mutant Collection

The diagnostic and therapeutic agent gallium offers multiple clinical and commercial uses including the treatment of cancer and the localization of tumors, among others. Further, this metal has been proven to be an effective antimicrobial agent against a number of microbes. Despite the latter, the fundamental mechanisms of gallium action have yet to be fully identified and understood. To further the development of this antimicrobial, it is imperative that we understand the mechanisms by which gallium interacts with cells. As a result, we screened the Escherichia coli Keio mutant collection as a means of identifying the genes that are implicated in prolonged gallium toxicity or resistance and mapped their biological processes to their respective cellular system. We discovered that the deletion of genes functioning in response to oxidative stress, DNA or iron–sulfur cluster repair, and nucleotide biosynthesis were sensitive to gallium, while Ga resistance comprised of genes involved in iron/siderophore import, amino acid biosynthesis and cell envelope maintenance. Altogether, our explanations of these findings offer further insight into the mechanisms of gallium toxicity and resistance in E. coli.

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