Inactivation of Escherichia coli O157:H7 and Listeria monocytogenes by PR-26, a Synthetic Antibacterial Peptide†

2001 ◽  
Vol 64 (12) ◽  
pp. 1929-1934 ◽  
Author(s):  
THIRUNAVUKKARASU ANNAMALAI ◽  
KUMAR S. VENKITANARAYANAN ◽  
THOMAS A. HOAGLAND ◽  
MAZHAR I. KHAN
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Antibacterial Effect ◽  
Inhibitory Effect ◽  
Final Concentration ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Complete Inactivation ◽  
Peptone Water ◽  
Water Ph

This study reports the antibacterial effect of PR-26, a synthetic peptide derived from the first 26 amino acid sequence of PR-39, an antimicrobial peptide isolated from porcine neutrophils. A three-strain mixture of Escherichia coli O157:H7 or Listeria monocytogenes of approximately 108 CFU was inoculated to a final concentration of 107 CFU/ml in 1% peptone water (pH 7.0), containing 50 or 75 μg/ml of PR-26, and incubated at 37°C for 0, 6, 12, and 24 h; at 24°C for 0, 12, 24, and 36 h; or at 10 or 4°C for 0, 24, 72, and 120 h. Control samples included 1% peptone water inoculated with each pathogen mixture but containing no PR-26. The surviving population of each pathogen at each sampling time was determined by plating on tryptic soy agar with incubation at 37°C for 24 h. At 37°C, PR-26 decreased E. coli O157:H7 and L. monocytogenes populations by >5.0 log CFU/ml at 12 h, with complete inactivation at 24 h. At 24°C, PR-26 reduced E. coli O157:H7 and L. monocytogenes by approximately 3.5, 4.0, and 4.5 log CFU/ml at the end of 12-, 24-, and 36-h incubations, respectively. At 4 and 10°C, the inhibitory effect of PR-26 on E. coli O157:H7 and L. monocytogenes was significantly lower (P < 0.05) than that at 37 and 24°C; a 2- to 3-log CFU/ml reduction was observed at 120-h incubation. Results indicate that PR-26 could potentially be used as an antimicrobial agent, but applications in appropriate foods need to be validated.

Effects of UV Irradiation on Selected Pathogens in Peptone Water and on Stainless Steel and Chicken Meat

2002 ◽  
Vol 65 (7) ◽  
pp. 1142-1145 ◽  
Author(s):  
T. KIM ◽  
J. L. SILVA ◽  
T. C. CHEN
Keyword(s):  
Escherichia Coli ◽  
Stainless Steel ◽  
Listeria Monocytogenes ◽  
Uv Irradiation ◽  
Processing Time ◽  
Chicken Meat ◽  
Escherichia Coli O157 ◽  
Uv Treatment ◽  
E Coli ◽  
Peptone Water

Effects of intensity and processing time of 254 nm UV irradiation on Listeria monocytogenes, Escherichia coli O157: H7, and Salmonella Typhimurium were investigated. Intensities measured at 5.08, 10.1, 15.2, and 20.3 cm from the light source were 1,000, 500, 250, and 150 μW/cm2, respectively. Intensities of 250 or 500 μW/cm2 reduced all suspended pathogen cells in peptone water about 5 log cycles after 2 min and completely inactivated L. monocytogenes and E. coli O157:H7 after 3 min by reductions of 8.39 and 8.64 log cycles, respectively. Intensities of 250 or 500 μW/cm2 also reduced (P ≤ 0.05) the tested pathogens inoculated on stainless steel (SS) chips, and E. coli O157:H7 was completely destroyed at 500 μW/cm2 for 3 min. After UV treatment for 3 min at 500 μW/cm2, all selected pathogens on chicken meat with or without skin showed reduction ranges from 0.36 to 1.28 log cycles. Results demonstrated that UV irradiation could effectively decrease pathogens in peptone water and on SS but that it was less effective on chicken meat.

scholarly journals Efficacy of Electrolyzed Oxidizing Water for Inactivating Escherichia coli O157:H7, Salmonella enteritidis, and Listeria monocytogenes

1999 ◽  
Vol 65 (9) ◽  
pp. 4276-4279 ◽  
Author(s):  
Kumar S. Venkitanarayanan ◽  
Gabriel O. Ezeike ◽  
Yen-Con Hung ◽  
Michael P. Doyle
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Salmonella Enteritidis ◽  
Sampling Time ◽  
Deionized Water ◽  
Escherichia Coli O157 ◽  
Water Control ◽  
E Coli ◽  
Complete Inactivation ◽  
Control Samples

ABSTRACT The efficacy of electrolyzed oxidizing water for inactivatingEscherichia coli O157:H7, Salmonella enteritidis, and Listeria monocytogenes was evaluated. A five-strain mixture of E. coli O157:H7,S. enteritidis, or L. monocytogenes of approximately 108 CFU/ml was inoculated in 9 ml of electrolyzed oxidizing water (treatment) or 9 ml of sterile, deionized water (control) and incubated at 4 or 23°C for 0, 5, 10, and 15 min; at 35°C for 0, 2, 4, and 6 min; or at 45°C for 0, 1, 3, and 5 min. The surviving population of each pathogen at each sampling time was determined on tryptic soy agar. At 4 or 23°C, an exposure time of 5 min reduced the populations of all three pathogens in the treatment samples by approximately 7 log CFU/ml, with complete inactivation by 10 min of exposure. A reduction of ≥7 log CFU/ml in the levels of the three pathogens occurred in the treatment samples incubated for 1 min at 45°C or for 2 min at 35°C. The bacterial counts of all three pathogens in control samples remained the same throughout the incubation at all four temperatures. Results indicate that electrolyzed oxidizing water may be a useful disinfectant, but appropriate applications need to be validated.

scholarly journals Survival of Escherichia coli O157:H7, Listeria monocytogenes 4b and Yersinia enterocolitica O3 in ayran and modified kefir as pre- and postfermentation contaminant

2012 ◽  
Vol 48 (No. 5) ◽  
pp. 126-132 ◽  
Author(s):  
M. Gulmez ◽  
A. Guven
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Yersinia Enterocolitica ◽  
Cold Storage ◽  
Antibacterial Effect ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Microbiological Safety ◽  
Natural Flora ◽  
Long Life

The survival of Escherichia coli O157:H7, Listeria monocytogenes 4b and Yersinia enterocolitica O3 in traditional yogurt and kefir during fermentation, in ayran (a dairy beverage in Turkey), pasteurised (long-life) ayran, modified kefir (salted and diluted kefir) and pasteurised modified kefir during cold storage were investigated. Pasteurised samples were used to monitor the antibacterial effect of natural flora of yogurt and kefir during cold storage. Populations of all the strains were increased during fermentation, and thus pre-fermentation contamination appeared more rhisky than postfermentation contamination. Pasteurisation appeared not to be disaadventageous an application on the microbiological safety of the samples, neverthelessbiological benefits which may come from live microorganisms is lost. While E. coli O157:H7 and L. monocytogenes 4b survived for up to 21 days in all samples, Y. enterocolitica O3 survived only for 14 days in modified kefir. Yogurt microflora appeared to be more suppressive on the pathogens than that of kefir.

Impact of pH Enhancement on Populations of Salmonella, Listeria monocytogenes, and Escherichia coli O157:H7 in Boneless Lean Beef Trimmings†

2003 ◽  
Vol 66 (5) ◽  
pp. 874-877 ◽  
Author(s):  
STEVEN E. NIEBUHR ◽  
J. S. DICKSON
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Ground Beef ◽  
Final Concentration ◽  
Escherichia Coli O157 ◽  
Ammonia Gas ◽  
E Coli ◽  
Lean Beef ◽  
Pathogen Populations ◽  
Multiple Strains

Boneless lean beef trimmings were inoculated with multiple strains of salmonellae, Listeria monocytogenes, and Escherichia coli O157:H7 at levels of ca. 6 log10 CFU/g. pH enhancement with ammonia gas was then used to increase the pH of the trimmings to ca. 9.6. The product was then frozen, chipped, and compressed into blocks. pH enhancement reduced the populations of salmonellae, L. monocytogenes, and E. coli O157:H7 by approximately 4, 3, and 1 log10 cycles, respectively. After the product had been frozen and compressed into blocks, no salmonellae or E. coli O157:H7 were detectable by enumeration or after enrichment and isolation. The final populations of L. monocytogenes were reduced by ca. 3 log10 cycles relative to the initial populations. When uninoculated pH-enhanced lean boneless trimmings were blended with inoculated ground beef to a final concentration of 15% (wt/wt), pathogen populations in the ground beef were reduced by approximately 0.2 log10 cycles.

scholarly journals ATIVIDADE ANTIMICROBIANA DE MICRORGANISMOS ISOLADOS DE GRÃOS DE KEFIR

2018 ◽  
Vol 19 (0) ◽  
Author(s):  
Priscila Alves Dias ◽  
Daiani Teixeira Silva ◽  
Cláudio Dias Timm
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Salmonella Enterica ◽  
Escherichia Coli O157 ◽  
E Coli

Resumo Kefir é o produto da fermentação do leite pelos grãos de kefir. Esses grãos contêm uma mistura simbiótica de bactérias e leveduras imersas em uma matriz composta de polissacarídeos e proteínas. Muitos benefícios à saúde humana têm sido atribuídos ao kefir, incluindo atividade antimicrobiana contra bactérias Gram positivas e Gram negativas. A atividade antimicrobiana de 60 microrganismos isolados de grãos de kefir, frente à Escherichia coli O157:H7, Salmonella enterica subsp. enterica sorotipos Typhimurium e Enteritidis, Staphylococcus aureus e Listeria monocytogenes, foi estudada através do teste do antagonismo. A ação antimicrobiana dos sobrenadantes das bactérias ácido-lácticas que apresentaram atividade no teste do antagonismo foi testada. O experimento foi repetido usando sobrenadantes com pH neutralizado. Salmonella Typhimurium e Enteritidis sobreviveram por 24 horas no kefir em fermentação. E. coli O157:H7, S. aureus e L. monocytogenes foram recuperados até 72 horas após o início da fermentação. Todos os isolados apresentaram atividade antimicrobiana contra pelo menos um dos patógenos usados no teste do antagonismo. Sobrenadantes de 25 isolados apresentaram atividade inibitória e três mantiveram essa atividade com pH neutralizado. As bactérias patogênicas estudadas sobreviveram por tempo superior àquele normalmente utilizado para a fermentação do kefir artesanal, o que caracteriza perigo em potencial para o consumidor quando a matéria-prima não apresentar segurança sanitária. Lactobacillus isolados de grãos de kefir apresentam atividade antimicrobiana contra cepas de E. coli O157:H7, Salmonella sorotipos Typhimurium e Enteritidis, S. aureus e L. monocytogenes além daquela exercida pela diminuição do pH.

Growth Inhibition of Escherichia coli O157:H7 and Listeria monocytogenes by Carvacrol and Eugenol Encapsulated in Surfactant Micelles

2005 ◽  
Vol 68 (12) ◽  
pp. 2559-2566 ◽  
Author(s):  
SYLVIA GAYSINSKY ◽  
P. MICHAEL DAVIDSON ◽  
BARRY D. BRUCE ◽  
JOCHEN WEISS
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Listeria Monocytogenes ◽  
Essential Oil ◽  
Growth Inhibition ◽  
Surfactant Concentration ◽  
Escherichia Coli O157 ◽  
Surfactant Micelles ◽  
E Coli ◽  
Oil Components

Growth inhibition of four strains of Escherichia coli O157:H7 (H1730, F4546, 932, and E0019) and Listeria monocytogenes (Scott A, 101, 108, and 310) by essential oil components (carvacrol and eugenol) solubilized in nonionic surfactant micelles (Surfynol 465 and 485W) was investigated. Concentrations of encapsulated essential oil components ranged from 0.02 to 1.25% depending on compound, surfactant type, and surfactant concentration (0.5 to 5%). Eugenol encapsulated in Surfynol 485W micelles was most efficient in inhibiting growth of the pathogens; 1% Surfynol 485W and 0.15% eugenol was sufficient to inhibit growth of all strains of E. coli O157:H7 and three of four strains of L. monocytogenes (Scott A, 310, and 108). The fourth strain, L. monocytogenes 101, was inhibited by 2.5% Surfynol and 0.225% eugenol. One percent Surfynol 485W in combination with 0.025% carvacrol was effective in inhibiting three of four strains of E. coli O157:H7. Strain H1730 was the most resistant strain, requiring 0.3% carvacrol and 5% surfactant for complete inhibition. Growth inhibition of L. monocytogenes by combinations of carvacrol and Surfynol 465 ranged between 0.15 and 0.35% and 1 and 3.75%, respectively. Generally, the antimicrobial activity of Surfynol 465 in combination with eugenol was higher than that for the combination with carvacrol. The potent activity was attributed to increased solubility of essential oil components in the aqueous phase due to the presence of surfactants and improved interactions of antimicrobials with microorganisms.

Antibacterial Effect of Monocaprylin on Escherichia coli O157:H7 in Apple Juice

2005 ◽  
Vol 68 (9) ◽  
pp. 1895-1899 ◽  
Author(s):  
MANOJ KUMAR MOHAN NAIR ◽  
HANEM ABOUELEZZ ◽  
THOMAS HOAGLAND ◽  
KUMAR VENKITANARAYANAN
Keyword(s):  
Escherichia Coli ◽  
Apple Juice ◽  
Antibacterial Effect ◽  
Storage Temperature ◽  
Escherichia Coli O157 ◽  
Organoleptic Properties ◽  
E Coli ◽  
Low Concentrations ◽  
Storage Temperatures ◽  
Control Samples

The antibacterial effect of low concentrations of monocaprylin on Escherichia coli O157:H7 in apple juice was investigated. Apple juice alone (control) or containing 2.5 mM (0.055%) or 5 mM monocaprylin was inoculated with a five-strain mixture of E. coli O157:H7 at ~6.0 log CFU/ml. The juice samples were stored at 23 or 4°C for 14 or 21 days, respectively, and the population of E. coli O157:H7 was determined on tryptic soy agar plates supplemented with 0.6% yeast extract. At both storage temperatures, the population of E. coli O157:H7 in monocaprylin-supplemented juice samples was significantly lower (P < 0.05) than that in the control samples. The concentration of monocaprylin and the storage temperature had a significant effect on the inactivation of E. coli O157:H7 in apple juice. Monocaprylin at 5 mM was significantly more effective than 2.5 mM monocaprylin for killing E. coli O157:H7 in apple juice. Inactivation of E. coli O157:H7 by monocaprylin was more pronounced in juice stored at 23°C than in the refrigerated samples. Results of this study indicated that monocaprylin is effective for killing E. coli O157:H7 in apple juice, but detailed sensory studies are needed to determine the organoleptic properties of apple juice containing monocaprylin.

Contamination of Intact Apples after Immersion in an Aqueous Environment Containing Escherichia coli O157:H7†

1999 ◽  
Vol 62 (5) ◽  
pp. 444-450 ◽  
Author(s):  
R. L. BUCHANAN ◽  
S. G. EDELSON ◽  
R. L. MILLER ◽  
G. M. SAPERS
Keyword(s):  
Escherichia Coli ◽  
Outer Core ◽  
Core Region ◽  
Effect Of Temperature ◽  
Aqueous Environment ◽  
Escherichia Coli O157 ◽  
Dye Uptake ◽  
E Coli ◽  
Golden Delicious ◽  
Peptone Water

The extent and location of Escherichia coli O157:H7 contamination after intact apples were immersed in cold (2°C) 1% peptone water containing approximately 3 × 107 CFU/ml was assessed using four apple varieties, Golden Delicious, McIntosh, Red Delicious, and Braeburn. Room temperature and refrigerated apples were used to determine the effect of temperature differential on E. coli infiltration. The highest levels of E. coli were associated with the outer core region of the apple, followed by the skin. Apples were subsequently treated by immersing them for 1 min in 2,000 mg/liter sodium hypochlorite, followed by a 1-min tapwater rinse. This treatment reduced pathogen levels by 1- to 3-log cycles but did not eliminate the microorganism, particularly from the outer core region. While E. coli was not detected in the inner core of most apples, warm fruit immersed in cold peptone water occasionally internalized the pathogen. The frequency and extent of internalization of the pathogen was less when cold apples were immersed in cold peptone water. Subsequent dye uptake studies with Golden Delicious apples indicated that approximately 6% of warm apples immersed into a cold dye solution accumulated dye via open channels leading from the blossom end into the core region. However, dye uptake did not occur when the dye solution was warmer than the apple.

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.

Simultaneous Enrichment of Shiga Toxin–Producing Escherichia coli O157 and O26 and Salmonella in Food Samples Using Universal Preenrichment Broth

2009 ◽  
Vol 72 (10) ◽  
pp. 2065-2070 ◽  
Author(s):  
MASASHI KANKI ◽  
KAZUKO SETO ◽  
JUNKO SAKATA ◽  
TETSUYA HARADA ◽  
YUKO KUMEDA
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Food Samples ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Significant Difference ◽  
Peptone Water ◽  
Radish Sprouts ◽  
Pork Samples ◽  
Better Than

Universal preenrichment broth (UPB) was compared with modified Escherichia coli broth with novobiocin (mEC+n) for enrichment of Shiga toxin–producing E. coli O157 and O26, and with buffered peptone water (BPW) for preenrichment of Salmonella enterica. Ten strains each of the three pathogens were inoculated into beef and radish sprouts following thermal, freezing, or no treatment. With regard to O157 and O26, UPB incubated at 42°C recovered significantly more cells from inoculated beef than UPB at 35°C and from radish sprout samples than UPB at 35°C and mEC+n. With regard to Salmonella, UPB incubated at 42°C was as effective as UPB at 35°C and BPW at recovering cells from beef and radish sprout samples. No significant difference was noted between the effectiveness of UPB at 42°C and UPB at 35°C or BPW in the recovery of Salmonella from 205 naturally contaminated poultry samples. By using UPB at 42°C, one O157:H7 strain was isolated from the mixed offal of 53 beef samples, 6 cattle offal samples, and 50 pork samples all contaminated naturally, with no pathogen inoculation. The present study found that UPB incubated at 42°C was as effective as, or better than, mEC+n for enrichment of O157 and O26 and comparable to BPW for preenrichment of Salmonella. These findings suggest that a great deal of labor, time, samples, and space may be saved if O157, O26, and Salmonella are enriched simultaneously with UPB at 42°C.

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