The synergistic effect of Escherichia coli inactivation by sequential disinfection with low level chlorine dioxide followed by free chlorine

To the best of our knowledge, there was little information available on pathogen removal using low level disinfectant followed by free chlorine in sequential disinfection (SD). This study investigated Escherichia coli inactivation by four types of disinfection: single step disinfection (SSD), SD, traditional sequential disinfection (TSD) and mixed disinfectant disinfection (MDD). Results indicated that SD had higher ability to inactivate E. coli than the others, indicating there was a positive synergistic effect on chlorine disinfection by prior dosing with a low level of chlorine dioxide (ClO2). The ONPG assay suggested that the permeability of cell wall rather than the viability of E. coli were changed under 0.02 mg/l ClO2 treatment. The coexistence of residual ClO2 and free chlorine also plays an active synergistic effect. Additionally, temperature had a positive effect on E. coli inactivation in SD, while inactivation was reduced in alkaline compared to neutral and acidic conditions.

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

Journal of Food Protection ◽

10.4315/0362-028x-63.6.703 ◽

2000 ◽

Vol 63 (6) ◽

pp. 703-708 ◽

Cited By ~ 65

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.

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Comparison of Single and Combined Use of Catechin, Protocatechuic, and Vanillic Acids as Antioxidant and Antibacterial Agents against Uropathogenic Escherichia Coli at Planktonic and Biofilm Levels

Molecules ◽

10.3390/molecules23112813 ◽

2018 ◽

Vol 23 (11) ◽

pp. 2813 ◽

Cited By ~ 9

Author(s):

Ariadna Bernal-Mercado ◽

Francisco Vazquez-Armenta ◽

Melvin Tapia-Rodriguez ◽

Maria Islas-Osuna ◽

Veronica Mata-Haro ◽

...

Keyword(s):

Escherichia Coli ◽

Phenolic Compounds ◽

Synergistic Effect ◽

Vanillic Acid ◽

Protocatechuic Acid ◽

Uropathogenic Escherichia Coli ◽

E Coli ◽

Planktonic Bacteria ◽

Combined Use ◽

Antioxidant Agents

The objective of this study was to evaluate the effect of combining catechin, protocatechuic, and vanillic acids against planktonic growing, adhesion, and biofilm eradication of uropathogenic Escherichia coli (UPEC), as well as antioxidant agents. The minimum inhibitory concentrations (MIC) of protocatechuic, vanillic acids and catechin against the growth of planktonic bacteria were 12.98, 11.80, and 13.78 mM, respectively. Mixing 1.62 mM protocatechuic acid + 0.74 mM vanillic acid + 0.05 mM catechin resulted in a synergistic effect acting as an MIC. Similarly, the minimum concentrations of phenolic compounds to prevent UPEC adhesion and biofilm formation (MBIC) were 11.03 and 7.13 mM of protocatechuic and vanillic acids, respectively, whereas no MBIC of catechin was found. However, combinations of 1.62 mM protocatechuic acid + 0.74 mM vanillic acid + 0.05 mM catechin showed a synergistic effect acting as MBIC. On the other hand, the minimum concentrations to eradicate biofilms (MBEC) were 25.95 and 23.78 mM, respectively. The combination of 3.20 mM protocatechuic acid, 2.97 mM vanillic acid, and 1.72 mM catechin eradicated pre-formed biofilms. The antioxidant capacity of the combination of phenolics was higher than the expected theoretical values, indicating synergism by the DPPH•, ABTS, and FRAP assays. Effective concentrations of catechin, protocatechuic, and vanillic acids were reduced from 8 to 1378 times when combined. In contrast, the antibiotic nitrofurantoin was not effective in eradicating biofilms from silicone surfaces. In conclusion, the mixture of phenolic compounds was more effective in preventing cell adhesion and eradicating pre-formed biofilms of uropathogenic E. coli than single compounds and nitrofurantoin, and showed antioxidant synergy.

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Quantitative Determination of the Role of Lettuce Leaf Structures in Protecting Escherichia coli O157:H7 from Chlorine Disinfection

Journal of Food Protection ◽

10.4315/0362-028x-64.2.147 ◽

2001 ◽

Vol 64 (2) ◽

pp. 147-151 ◽

Cited By ~ 89

Author(s):

KAZUE TAKEUCHI ◽

JOSEPH F. FRANK

Keyword(s):

Escherichia Coli ◽

Leaf Surface ◽

Dead Cell ◽

Escherichia Coli O157 ◽

E Coli ◽

Chlorine Disinfection ◽

Sytox Green ◽

Tissue Surface ◽

Confocal Scanning

Viability of Escherichia coli O157:H7 cells on lettuce leaves after 200 mg/liter (200 ppm) chlorine treatment and the role of lettuce leaf structures in protecting cells from chlorine inactivation were evaluated by confocal scanning microscopy (CSLM). Lettuce samples (2 by 2 cm) were inoculated by immersing in a suspension containing 109 CFU/ml of E. coli O157: H7 for 24 ± 1 h at 4°C. Rinsed samples were treated with 200 mg/liter (200 ppm) chlorine for 5 min at 22°C. Viability of E. coli O157:H7 cells was evaluated by CSLM observation of samples stained with Sytox green (dead cell stain) and Alexa 594 conjugated antibody against E. coli O157:H7. Quantitative microscopic observations of viability were made at intact leaf surface, stomata, and damaged tissue. Most E. coli O157:H7 cells (68.3 ± 16.2%) that had penetrated 30 to 40 μm from the damaged tissue surface remained viable after chlorine treatment. Cells on the surface survived least (25.2 ± 15.8% survival), while cells that penetrated 0 to 10 μm from the damaged tissue surface or entered stomata showed intermediate survival (50.8 ± 13.5 and 45.6 ± 9.7% survival, respectively). Viability was associated with the depth at which E. coli O157:H7 cells were in the stomata. Although cells on the leaf surface were mostly inactivated, some viable cells were observed in cracks of cuticle and on the trichome. These results demonstrate the importance of lettuce leaf structures in the protection of E. coli O157:H7 cells from chlorine inactivation.

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Tyrosine phosphorylation-dependent localization of TmaR that controls activity of a major bacterial sugar regulator by polar sequestration

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2016017118 ◽

2020 ◽

Vol 118 (2) ◽

pp. e2016017118

Author(s):

Tamar Szoke ◽

Nitsan Albocher ◽

Sutharsan Govindarajan ◽

Anat Nussbaum-Shochat ◽

Orna Amster-Choder

Keyword(s):

Escherichia Coli ◽

Sugar Uptake ◽

Dependent Manner ◽

Tyrosine Residue ◽

Sugar Consumption ◽

E Coli ◽

Acidic Conditions ◽

Enzyme I ◽

Uptake And Metabolism ◽

Protein Enzyme

The poles of Escherichia coli cells are emerging as hubs for major sensory systems, but the polar determinants that allocate their components to the pole are largely unknown. Here, we describe the discovery of a previously unannotated protein, TmaR, which localizes to the E. coli cell pole when phosphorylated on a tyrosine residue. TmaR is shown here to control the subcellular localization and activity of the general PTS protein Enzyme I (EI) by binding and polar sequestration of EI, thus regulating sugar uptake and metabolism. Depletion or overexpression of TmaR results in EI release from the pole or enhanced recruitment to the pole, which leads to increasing or decreasing the rate of sugar consumption, respectively. Notably, phosphorylation of TmaR is required to release EI and enable its activity. Like TmaR, the ability of EI to be recruited to the pole depends on phosphorylation of one of its tyrosines. In addition to hyperactivity in sugar consumption, the absence of TmaR also leads to detrimental effects on the ability of cells to survive in mild acidic conditions. Our results suggest that this survival defect, which is sugar- and EI-dependent, reflects the difficulty of cells lacking TmaR to enter stationary phase. Our study identifies TmaR as the first, to our knowledge, E. coli protein reported to localize in a tyrosine-dependent manner and to control the activity of other proteins by their polar sequestration and release.

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Development of an Algorithm for Feed-Forward Chlorine Dosing of Lettuce Wash Operations and Correlation of Chlorine Profile with Escherichia coli O157:H7 Inactivation

Journal of Food Protection ◽

10.4315/0362-028x.jfp-13-352 ◽

2014 ◽

Vol 77 (4) ◽

pp. 558-566 ◽

Cited By ~ 19

Author(s):

BIN ZHOU ◽

YAGUANG LUO ◽

XIANGWU NOU ◽

PATRICIA MILLNER

Keyword(s):

Escherichia Coli ◽

Reduction Potential ◽

Free Chlorine ◽

Organic Load ◽

Escherichia Coli O157 ◽

Feed Forward ◽

E Coli ◽

Wash Solution ◽

Oxidation Reduction ◽

Oxidation Reduction Potential

The dynamic interactions of chlorine and organic matter during a simulated fresh-cut produce wash process and the consequences for Escherichia coli O157:H7 inactivation were investigated. An algorithm for a chlorine feed-forward dosing scheme to maintain a stable chlorine level was further developed and validated. Organic loads with chemical oxygen demand of 300 to 800 mg/liter were modeled using iceberg lettuce. Sodium hypochlorite (NaOCl) was added to the simulated wash solution incrementally. The solution pH, free and total chlorine, and oxidation-reduction potential were monitored, and chlorination breakpoint and chloramine humps determined. The results indicated that the E. coli O157:H7 inactivation curve mirrored that of the free chlorine during the chlorine replenishment process: a slight reduction in E. coli O157:H7 was observed as the combined chlorine hump was approached, while the E. coli O157:H7 cell populations declined sharply after chlorination passed the chlorine hump and decreased to below the detection limit (<0.75 most probable number per ml) after the chlorination breakpoint was reached. While the amounts of NaOCl required for reaching the chloramine humps and chlorination breakpoints depended on the organic loads, there was a linear correlation between NaOCl input and free chlorine in the wash solution once NaOCl dosing passed the chlorination breakpoint, regardless of organic load. The data obtained were further exploited to develop a NaOCl dosing algorithm for maintaining a stable chlorine concentration in the presence of an increasing organic load. The validation tests results indicated that free chlorine could be maintained at target levels using such an algorithm, while the pH and oxidation-reduction potential were also stably maintained using this system.

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Antibacterial Activity of Geraniol in Combination with Standard Antibiotics against Staphylococcus aureus, Escherichia coli and Helicobacter pylori

Natural Product Communications ◽

10.1177/1934578x1801300701 ◽

2018 ◽

Vol 13 (7) ◽

pp. 1934578X1801300 ◽

Cited By ~ 1

Author(s):

Subrat Kumar Bhattamisra ◽

Chew Hui Kuean ◽

Lee Boon Chieh ◽

Vivian Lee Yean Yan ◽

Chin Koh Lee ◽

...

Keyword(s):

Escherichia Coli ◽

Staphylococcus Aureus ◽

Helicobacter Pylori ◽

Antibacterial Activity ◽

Synergistic Effect ◽

Inhibitory Concentration ◽

Therapeutic Potential ◽

E Coli ◽

Checkerboard Assay ◽

H Pylori

The antibacterial activity of geraniol and its effect in combination with ampicillin, amoxicillin and clarithromycin against Staphylococcus aureus, Escherichia coli and Helicobacter pylori was tested. The minimum inhibitory concentrations (MICs) and combinatory effects of geraniol against the bacteria were assessed by using the modified broth microdilution and checkerboard assay, respectively. The combinatory effect is expressed as fractional inhibitory concentration index (FICI). The MIC of geraniol against S. aureus, E. coli and H. pylori was found to be 11200, 5600, and 7325 μg/mL, respectively. A significant synergistic effect was observed with geraniol and ampicillin against S. aureus with FICI in the range 0.19 to 0.32. Geraniol and ampicillin exhibited a partial synergistic effect against E. coli. A similar effect was observed with geraniol and clarithromycin against S. aureus. A partial synergistic effect was observed with clarithromycin and geraniol against H. pylori with the FICI value in the range 0.86 to 0.89. An additive effect was observed with geraniol and amoxicillin combination against H. pylori. However, the amoxicillin and clarithromycin dose was reduced by thirty-two fold when combined with geraniol against H. pylori. The anti- H. pylori effect of geraniol with clarithromycin and amoxicillin could be of potential interest in the treatment of H. pylori infection and associated ulcers in humans. Further, geraniol, in combination with other antibiotics, has substantial therapeutic potential against S. aureus and E.coli infection.

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Role of enteric pathogens in the aetiology of neonatal diarrhoea in lambs and goat kids in Spain

Epidemiology and Infection ◽

10.1017/s0950268800001321 ◽

1996 ◽

Vol 117 (1) ◽

pp. 203-211 ◽

Cited By ~ 80

Author(s):

M. Muñoz ◽

M. Álvarez ◽

I. Lanza ◽

P. Cármenes

Keyword(s):

Escherichia Coli ◽

Synergistic Effect ◽

Cryptosporidium Parvum ◽

Clinical Characteristics ◽

Enteric Pathogens ◽

E Coli ◽

Neonatal Diarrhoea ◽

Group A ◽

Group B

SummaryFaeces samples from diarrhoeic and non-diarrhoeic lambs and goat kids aged 1–45 days were examined for enteric pathogens.Cryptosporidium parvumwas detected in both diarrhoeic lambs (45%) and goat kids (42%) but not in non-diarrhoeic animals. F5+(K99+) and/or F41+Escherichia colistrains were isolated from 26% and 22% of the diarrhoeic lambs and goat kids, respectively, although these strains, which did not produce enterotoxins ST I or LT I, were found with similar frequencies in non-diarrhoeic animals. A F5−F41−ST I+E. colistrain was isolated from a diarrhoeic lamb (0·6%). VerotoxigenicE. coliwas isolated from both diarrhoeic and non-diarrhoeic lambs (4·1% and 8·2%, respectively) and there was no association between infection and diarrhoea. The prevalence of group A rotavirus infection in diarrhoeic lambs was very low (2·1%). Groups A and B rotaviruses were detected in three (8·1%) and five (13·5%) diarrhoeic goat kids from two single outbreaks. Group C rotaviruses were detected in four non-diarrhoeic goat kids. An association of diarrhoea and infection was demonstrated only for group B rotavirus.Clostridium perfringenswas isolated from 10·8% of the diarrhoeic goat kids but not from non-diarrhoeic goat kids or lambs.Salmonella arizonaewas isolated from a diarrhoeic goat kid (2·7%) and the clinical characteristics of the outbreaks where these two latter enteropathogens were found different from the rest. Picobirnaviruses were detected in a diarrhoeic lamb. No coronaviruses were detected using a bovine coronavirus ELISA. No evidence was found of synergistic effect between the agents studied. Enteric pathogens were not found in four (8·7%) and three (20%) outbreaks of diarrhoea in lambs and goat kids, respectively.

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Resistance and Virulence Mechanisms of Escherichia coli Selected by Enrofloxacin in Chicken

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01824-18 ◽

2019 ◽

Vol 63 (5) ◽

Cited By ~ 3

Author(s):

Jun Li ◽

Haihong Hao ◽

Menghong Dai ◽

Heying Zhang ◽

Jianan Ning ◽

...

Keyword(s):

Escherichia Coli ◽

Efflux Pumps ◽

Genetic Alterations ◽

Site Directed Mutagenesis ◽

Single Mutation ◽

Genetic Characteristics ◽

Content Type ◽

E Coli ◽

Low Level ◽

High Level

ABSTRACT This study aimed to investigate the genetic characteristics, antibiotic resistance patterns, and novel mechanisms involved in fluoroquinolone (FQ) resistance in commensal Escherichia coli isolates. The E. coli isolates were recovered from a previous clinical study and subjected to antimicrobial susceptibility testing and molecular typing. Known mechanisms of FQ resistance (target site mutations, plasmid-mediated quinolone resistance [PMQR] genes, relative expression levels of efflux pumps and porins) were detected using DNA sequencing of PCR products and real-time quantitative PCR. Whole-genome shotgun sequencing was performed on 11 representative strains to screen for single nucleotide polymorphisms (SNPs). The function of a key SNP (A1541G) was investigated by site-directed mutagenesis and allelic exchange. The results showed that long-term enrofloxacin treatment selected multidrug-resistant (MDR) E. coli isolates in the chicken gut and that these E. coli isolates had diverse genetic backgrounds. Multiple genetic alterations, including double mutations on GyrA (S83L and D87N), a single mutation on ParC (S80I) and ParE (S458E), activation of efflux pumps, and the presence of the QnrS1 protein, contributed to the high-level FQ resistance (enrofloxacin MIC [MICENR] ≥ 128 μg/ml), while the relatively low-level FQ resistance (MICENR = 8 or 16 μg/ml) was commonly mediated by decreased expression of the porin OmpF, besides enhancement of the efflux pumps. No significant relationship was observed between resistance mechanisms and virulence genes. Introduction of the A1541G mutation on aegA was able to increase FQ susceptibility by 2-fold. This study contributes to a better understanding of the development of MDR and the differences underlying the mechanisms of high-level and low-level FQ resistance in E. coli.

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Inactivation of Escherichia coli by Ultrasound Combined with Nisin

Journal of Food Protection ◽

10.4315/0362-028x.jfp-18-023 ◽

2018 ◽

Vol 81 (6) ◽

pp. 993-1000 ◽

Cited By ~ 5

Author(s):

ZUWEN WANG ◽

XIUFANG BI ◽

RUI XIANG ◽

LIYI CHEN ◽

XIAOPING FENG ◽

...

Keyword(s):

Escherichia Coli ◽

Synergistic Effect ◽

Linear Models ◽

Treatment Time ◽

Nutrient Broth ◽

Inactivation Kinetics ◽

Growth Phases ◽

E Coli ◽

Kinetics Of ◽

Inactivation Effect

ABSTRACT The aim of this study was to investigate the inactivation of nonpathogenic Escherichia coli in nutrient broth and milk through the use of either ultrasound (US) alone or US combined with nisin (US + nisin) treatments. The E. coli cells were treated at 0 to 55°C, 242.04 to 968.16 W/cm2 for 0 to 15 min. The results showed that the inactivation of E. coli by US and US + nisin increased when the temperature, US power density, and treatment time were increased. The inactivation kinetics of E. coli in nutrient broth by US and US + nisin both conformed to linear models. The largest reductions of 2.89 and 2.93 log cycles by US and US + nisin, respectively, were achieved at 968.16 W/cm2 and at 25°C for 15 min. The suspension media of the E. coli cells influenced the inactivation effect of US, while the growth phases of E. coli cells did not affect their resistance to US. Under all experiment conditions of this study, the differences between US and US + nisin in their respective inactivation effects on E. coli were not obvious. The results suggested that nisin had either no effect at all or a weak synergistic effect with US and that the E. coli cells were inactivated mainly by US, thus indicating that the inactivation of E. coli by US is an “all or nothing” event.

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Inactivation of Escherichia coli and Staphyloccocus aureus in Litchi Juice by Dimethyl Dicarbonate (DMDC) Combined With Nisin

Journal of Food Research ◽

10.5539/jfr.v3n3p1 ◽

2014 ◽

Vol 3 (3) ◽

pp. 1 ◽

Cited By ~ 4

Author(s):

Yuanshan Yu ◽

Yujuan Xu ◽

Jijun Wu ◽

Gengsheng Xiao ◽

Jing Wen ◽

...

Keyword(s):

Escherichia Coli ◽

Synergistic Effect ◽

Ph Value ◽

Inactivation Rate ◽

Gram Positive ◽

Gram Negative ◽

E Coli ◽

Complete Inactivation ◽

Staphyloccocus Aureus ◽

Addition Level

Inactivation of Gram-negative Escherichia coli and Gram-positive Staphyloccocus aureus in litchi juice by DMDC combined with nisin was individually investigated. A 1.66 log cycles reduction of E. coli and 2.03 log cycles reduction of S. aureus in litchi juice (pH 4.5) added without nisin was achieved as exposed to 150 mg/l DMDC at 30 °C for 1 h, and the inactivation rate of E. coli and S. aureus during initial 1 h was far greater than during the remaining 5 h. As exposed to 150 mg/l DMDC at 30 °C for 1 h, the inactivation of E. coli and S. aureus in the litchi juice showed a trend toward increase with increasing of nisin addition level in the range from 0 to 200 IU/ml. Moreover, DMDC and nisin exhibited a synergistic effect on the inactivation of E. coli and S. aureus in litchi juice, and the inactivation of E. coli and S. aureus in the litchi juice also depends on the temperature of litchi juice, pH value of litchi juice and DMDC concentration when treated with DMDC and nisin. In addition, E. coli showed higher resistance to nisin as comparing with S. aureus. After E. coli and S. aureus in the litchi juice of pH 4.0 were individually treated with 150 mg/l DMDC combined with 200 IU/ml nisin at 30 °C for 1 h, a complete inactivation of S. aureus (6.59 log cycles) was achieved, but only 3.52 log cycles reduction of E. coli was observed.

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