Category Archives: E.coli

USA – FDA Sampling of Romaine Lettuce in Yuma Finds No Widespread STEC or Salmonella Contamination

Posted on August 19, 2019 by | Leave a comment

Food Safety Tech

Following last year’s widespread E.coli O157 outbreak involving romaine lettuce linked to the Yuma, Arizona growing region (Spring 2018), FDA launched a sampling assignment to test romaine lettuce for pathogenic Shiga toxin-producing Escherichia coli (STEC) and Salmonella spp. The microbiological surveillance samplingbegan on December 18, 2018 in the Yuma region and focused on 26 commercial coolers and cold storage facilities to allow FDA to sample multiple farms from several locations at once. The agency collected and tested a total of 188 samples for both pathogens. It did not detect Salmonella in any sample; STEC was detected in one sample, but additional analysis found that the bacteria was not pathogenic.

“The findings of this assignment suggest that there was no widespread Salmonella or STEC contamination of romaine lettuce from the Yuma growing region during the period when sampling occurred. As a next step, the FDA is working with leafy green stakeholders in the Yuma region to consider a longer-term environmental study to identify and control risks that will prevent future outbreaks, with the ultimate goal of protecting consumers. – FDA

The point of the sampling assignment was to determine whether target pathogens were present, and if so, to respond quickly before contaminated products reached consumers.

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Posted in E.coli, E.coli O157, E.coli O157:H7, food contamination, food handler, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Poisoning, food recall, Food Safety, Food Safety Alert, Food Testing, Food Toxin, Salmonella, Uncategorized

USA – Lake Nokomis E. coli Outbreak Has Sickened 49

Posted on August 19, 2019 by | Leave a comment

Food Poisoning Bulletin

The Lake Nokomis E. coli outbreak has now sickened 49 people, including the three confirmed cases of Shiga toxin-producing E. coli (STEC) in children that were announced earlier this week, according to a news release by the Minnesota Department of Health. That lake is located in Minneapolis.

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Posted in Contaminated water, E.coli, Food Micro Blog, Food Microbiology Blog, STEC, Uncategorized, Water, water microbiology

Research – Occurrence of Escherichia coli O157:H7 in Pest Flies Captured in Leafy Greens Plots Grown Near a Beef Cattle Feedlot

Posted on August 16, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Leafy greens are leading vehicles for Escherichia coli O157:H7 foodborne illness. Pest flies can harbor this pathogen and may disseminate it to produce. We determined the occurrence of E. coli O157:H7–positive flies in leafy greens planted up to 180 m from a cattle feedlot and assessed their relative risk to transmit this pathogen to leafy greens. The primary fly groups captured on sticky traps at the feedlot and leafy greens plots included house flies (Musca domestica L.), face flies (Musca autumnalisL.), stable flies (Stomoxys calcitrans L.), flesh flies (family Sarcophagidae), and blow flies (family Calliphoridae). E. coliO157:H7 carriage rates of house, face, flesh, and blow flies were similar (P > 0.05), ranging from 22.3 to 29.0 flies per 1,000 flies. In contrast, the carriage rate of stable flies was lower at 1.1 flies per 1,000 flies (P < 0.05). Differences in carriage rates are likely due to the uses of fresh bovine feces and manure by these different pest fly groups. E. coli O157:H7 carriage rates of total flies did not differ (P > 0.05) by distance (ranging from 0 to 180 m) from the feedlot. Most fly isolates were the same predominant pulsed-field gel electrophoresis types found in feedlot surface manure and leafy greens, suggesting a possible role for flies in transmitting E. coli O157:H7 to the leafy greens. However, further research is needed to clarify this role and to determine set-back distances between cattle production facilities and produce crops that will reduce the risk for pathogen contamination by challenging mechanisms like flies.

HIGHLIGHTS

  • E. coli O157:H7 was common in flies captured in leafy greens plots near a feedlot.

  • E. coli O157:H7 carriage rates of house, face, flesh, and blow flies were similar.

  • Stable flies had lower E. coli O157:H7 carriage than the other four fly groups.

  • E. coli O157:H7 carriage of total flies was not affected by distance up to 180 m.

  • Research is needed to determine risk for leafy green contamination by pest flies.

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Posted in E.coli, E.coli O157, E.coli O157:H7, Food Illness, Food Micro Blog, Food Microbiology Blog, Foodborne Illness, Illness, microbial contamination, Microbiology, Uncategorized

Research – Ultrasound treatment combined with fumaric acid for inactivating food-borne pathogens in apple juice and its mechanisms

Posted on August 16, 2019 by | Leave a comment

Science Direct

Highlights

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The combination of Ultrasound (US) and fumaric acid (FA) showed a synergistic bactericidal effect in apple juice.

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US-FA combined treatment of apple juice did not affect quality.

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Cell membrane damage was the main mechanism of US-FA synergistic lethal effect.

Abstract

The purpose of this study was to evaluate the synergistic bactericidal efficacy of combining ultrasound (US) and fumaric acid (FA) treatment against Escherichia coliO157:H7, Salmonella Typhimurium, and Listeria monocytogenes in apple juice and to identify the synergistic bactericidal mechanisms. Additionally, the effect of combination treatment on juice quality was determined by measuring the changes in color, pH, non-enzymatic browning index, and total phenolic content. A mixed cocktail of the three pathogens was inoculated into apple juice, followed by treatment with US (40 kHz) alone, FA (0.05, 0.1, and 0.15%) alone, and a combination of US and FA for 1, 2, 3, 4, and 5 min. Combined US and 0.15% FA treatment for 5 min achieved 5.67, 6.35, and 3.47 log reductions in E. coli O157:H7, S.Typhimurium, and L. monocytogenes, respectively, with the 1.55, 2.37, and 0.57 log CFU reductions attributed to the synergistic effect. Although the pH value slightly decreased as FA increased, there were no significant (P > 0.05) differences in color values, browning indices, and phenolic content between untreated and treated samples. To identify the mechanism of this synergistic bactericidal action, membrane integrity, malfunctions in the membrane efflux pump, and intracellular enzyme activity were measured. The analyses confirmed that damage to the cell envelope (membrane integrity and efflux pump) was strongly related to the synergistic microbial inactivation. These results suggest that simultaneous application of US treatment and FA is a novel method for ensuring the microbial safety of apple juice.

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Posted in E.coli, E.coli O157, E.coli O157:H7, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Technology, Listeria, Listeria monocytogenes, microbial contamination, Microbiology, Salmonella, Technology, Uncategorized

Research – Whole Genome Sequencing Characterization of Shiga Toxin–Producing Escherichia coli Isolated from Flour from Swiss Retail Markets

Posted on August 15, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Shiga toxin–producing Escherichia coli (STEC) strains are often found in food and cause human infections. Although STEC O157:H7 is most often responsible for human disease, various non-O157 subtypes have caused individual human infections or outbreaks. The importance of STEC serogroup typing is decreasing while detection of virulence gene patterns has become more relevant. Whole genome sequencing (WGS) reveals the entire spectrum of pathogen information, such as toxin variant, serotype, sequence type, and virulence factors. Flour has not been considered as a vector for STEC; however, this product has been associated with several STEC outbreaks in the last decade. Flour is a natural product, and milling does not include a germ-reducing step. Flour is rarely eaten raw, but the risks associated with the consumption of unbaked dough are probably underestimated. The aim of this study was to determine the prevalence of STEC in flour samples (n = 93) collected from Swiss markets and to fully characterize the isolates by PCR assay and WGS. The prevalence of STEC in these flour samples was 10.8% as indicated by PCR, and a total of 10 STEC strains were isolated (two flour samples were positive for two STEC subtypes). We found one stx2-positve STEC isolate belonging to the classic serogroups frequently associated with outbreaks that could potentially cause severe disease. However, we also found several other common or less common STEC subtypes with diverse virulence patterns. Our results reveal the benefits of WGS as a characterization tool and that flour is a potentially and probably underestimated source for STEC infections in humans.

HIGHLIGHTS

  • Several STEC serotypes, including O26, were isolated from 8 (8.6%) of 93 flour samples.

  • STEC isolates from flour had a variety of virulence patterns.

  • Flour is a probably underestimated source of STEC infections in humans.

  • WGS for STEC characterization is more comprehensive than common serotyping.

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Posted in E.coli, E.coli O157, E.coli O157:H7, E.coli O26, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Poisoning, Food Safety, Food Technology, Food Testing, Food Toxin, STEC, STX 1, STX 2, Uncategorized

Research – Desiccation and Thermal Resistance of Escherichia coli O121 in Wheat Flour

Posted on August 12, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Non-O157 Shiga toxin–producing Escherichia coli infections have recently been associated with wheat flour on two separate accounts in the United States and Canada. However, there is little information regarding the thermal resistance and longevity of non-O157 Shiga toxin–producing Escherichia coli during storage in low-moisture environments. The objectives of this study were to determine the thermal inactivation kinetics of E. coli O121 in wheat flour and to compare the thermal inactivation rates with those of other pathogens. Wheat flour, inoculated with E. coli O121, was equilibrated at 25°C to a water activity of 0.45 in a humidity-controlled conditioning chamber. Inoculated samples were treated isothermally at 70, 75, and 80°C, and posttreatment population survivor ratios were determined by plate counting. D– and z-values calculated with a log-linear model, were compared with those obtained in other studies. At 70, 75, and 80°C, the D-values for E. coli O121 were 18.16 ± 0.96, 6.47 ± 0.50, and 4.58 ± 0.40 min, respectively, and the z-value was 14.57 ± 2.21°C. Overall, E. coli O121 was observed to be slightly less thermally resistant than what has been previously reported for Salmonella Enteritidis PT30 in wheat flour as measured under the same conditions with the same methods.

HIGHLIGHTS

  • Thermal resistance of E. coli O121 in wheat flour was studied.

  • E. coli O121 exhibited greater survival upon desiccation than E. coli O157:H7.

  • E. coli O121 was slightly less thermally resistant than was previously reported for Salmonella in wheat flour.

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Posted in E.coli, E.coli O121, Food Micro Blog, Food Microbiology Blog, microbial contamination, Microbiology, STEC, Uncategorized

Research – Global Emergence of Colistin-Resistant Escherichia coli in Food Chains and Associated Food Safety Implications: A Review

Posted on August 12, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Antimicrobial resistance in bacteria represents one of the most important challenges for public health worldwide. Human infections from antimicrobial-resistant bacteria can be transmitted from person to person, via the environment (especially in the hospital environment), or via handling or eating contaminated foods. Colistin is well known as a last-resort antibiotic for the treatment of human infections; a recent study performed in the People’s Republic of China has revealed that colistin resistance is also conferred by the plasmid-mediated mcr-1 gene in Escherichia coli. After that discovery, further plasmid-mediated, colistin resistance genes have been detected. However, to date, only reports on E. coli carrying the mcr-1 gene (E. coli mcr-1+) in foodstuff are available. E. coli mcr-1+ has been isolated from food of animal origin and vegetables; this discovery has opened a debate among food safety experts. This review aims to provide a critical overview of the currently available scientific literature on the presence of the plasmid-mediated, colistin resistance gene E. coli mcr-1 in foodstuffs, focusing on the main implications and future perspectives for food safety.

HIGHLIGHTS

  • Antimicrobial resistance in the food chain: a One Health perspective.

  • Escherichia coli carries the mcr-1 gene in food-producing animals.

  • Escherichia coli carrying the mcr-1 gene in food from animals and vegetables is significant.

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Posted in Antibiotic Resistance, antimicrobial resistance, Antimicrobials, Colistin Resistant, E.coli, Food Micro Blog, Food Microbiology Blog, mcr-1 gene, microbial contamination, Microbiology, Uncategorized

Research – Conditions at the time of inoculation influence survival of attenuated Escherichia coli O157:H7 on field-inoculated lettuce

Posted on August 9, 2019 by | Leave a comment

Science Direct

Highlights

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Higher percentages of E. coli–positive plants recovered when inoculation was closer to harvest.

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Higher relative humidity and leaf surface wetness were measured during night inoculation.

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Short-term smaller initial population declines were observed after night inoculation.

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E. coli population sizes were similar 2 or more days after night or day inoculation.

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Probability of detecting E. coli was higher for longer times when inoculated at higher levels.

Abstract

The impact of plant development, environmental conditions at the time of inoculation, and inoculum concentration on survival of attenuated BSL1 Escherichia coli O157:H7 strain ATCC 700728 on field-grown romaine lettuce was evaluated over 3 years. E. coli 700728 was inoculated onto 4- and 6-week-old romaine lettuce plants in the Salinas Valley, CA, at night or the next morning with either low (5 log) or high (7 log) cell numbers per plant to simulate a single aqueous contamination event. At night, when leaf wetness and humidity levels were high, E. coli cell numbers declined by 0.5 log CFU/plant over the first 8–10 h. When applied in the morning, E. coli populations declined up to 2 log CFU/plant within 2 h. However, similar numbers of E. coli were retrieved from lettuce plants at 2 and 7 days. E. coli cell numbers per plant were significantly lower (P < 0.05) 7 days after application onto 4-week-old compared to 6-week-old plants. E. coli 700728 could be recovered by plating or enrichment from a greater proportion of plants for longer times when inoculated at high compared with low initial concentrations and after inoculation of 6-week-old plants compared with 4-week-old plants, even at the low initial inoculum. A contamination event near harvest or when leaf wetness and humidity levels are high may enhance survivability, even when low numbers of E. coli are introduced.

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Posted in E.coli, E.coli O157, E.coli O157:H7, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Poisoning, Food Safety, Food Technology, Food Testing, Uncategorized

RASFF Alert – E.coli – Live Cockles

Posted on August 2, 2019 by | Leave a comment

RASFF-Logo

RASFF – too high count of Escherichia coli (13000 MPN/100g) in live cockles from France in France

 

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Posted in E.coli, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Poisoning, food recall, Food Safety, Food Safety Alert, Food Testing, Food Toxin, RASFF, Uncategorized

USA – E. coli hits South Dakota – Sisseton Area

Posted on July 31, 2019 by | Leave a comment

Food Poison Journal

According to KSFY, the South Dakota Department of Health is investigating several cases of E. coli in northeastern South Dakota. The cases are in and around the Sisseton area.

Source not identified

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Posted in Contaminated water, E.coli, food contamination, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Pathogen, Food Safety, Food Safety Alert, Uncategorized, water microbiology, Water Safety