Category Archives: Microbiology

Research – Efficacy of a Mixed Peroxyorganic Acid Antimicrobial Wash Solution against Salmonella, Escherichia coli O157:H7 or Listeria monocytogenes on Cherry Tomatoes

Journal of Food Protection

A study was conducted to evaluate a new organic produce wash composed of a combination of organic acids and hydrogen peroxide, in the form of a mixed peroxyacid solution, against foodborne pathogens.  The mixed peroxyacid, composed of lactic acid, hydrogen peroxide and one or more fruit acids, was challenged against Salmonella enterica, E. coli O157:H7, or Listeria monocytogenes in suspension or on the surface of dip-inoculated cherry tomatoes.  Cherry tomatoes were also treated with 8 ppm of free chlorine added in the form of sodium hypochlorite (NaOCL).  When tested against planktonic cells in pure culture for 120 s, Salmonella, and E. coli O157:H7 were reduced by 7.5 and 7.1 log cycles with 0.40% of the peroxyacid solution, respectively, while L. monocytogenes decreased by 5.0 log by treatment with a 0.80% solution.  When cherry tomatoes were dip-inoculated and treated with 8 ppm free chlorine, Salmonella and E. coli O157:H7 populations decreased by 2.5 and 2.6 log, respectively, which were not significantly different than reductions incurred by sterile water rinses.  A 1.0% solution of peroxyacid solution, however, reduced the same microorganisms by 3.8 and 3.4 log per tomato, respectively, which was significantly greater ( P < 0.05) than reductions achieved by the 2 min sterile water rinse.  When dip-inoculated with L. monocytogenes, and treated, populations were reduced by 3.5 log per tomato with 1.0% peroxyacid solution which was greater ( P < 0.05) than reductions achieved by 8 ppm free Cl (2.6 log) or sterile water (1.7 log).  Results demonstrate that this peroxyacid combination antimicrobial wash may be an effective organic produce wash for preventing cross-contamination during the washing of cherry tomatoes, as well as being capable of inactivating up to 3.8, 3.4, and 3.5 log  per tomato of S. enterica, E. coli O157:H7 and L. monocytogenes , respectively.

Research – Antibacterial Effect of Oregano Essential Oil against Vibrio vulnificus and Its Mechanism

MDPI

Oregano essential oil (OEO) is an effective natural antibacterial agent, but its antibacterial activity against Vibrio vulnificus has not been widely studied. The aim of this study was to investigate the inhibitory effect and germicidal activity of OEO on V. vulnificus and its possible inhibition mechanism. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of OEO against four V. vulnificus strains (ATCC 27562 and three isolates from seafoods) were from 0.06 to 0.15 μL/mL. Compared with untreated bacteria, OEO reduced the concentration of intracellular adenosine triphosphate (ATP), hyperpolarized the cell membrane, increased the level of reactive oxygen species (ROS), and increased the concentration of intracellular malondialdehyde (MDA), but there was no obvious DNA damage at the OEO test concentration. It was indicated that OEO inactivated V. vulnificus by generating ROS which caused lipid peroxidation of cell membranes, thereby reducing the permeability and integrity of cell membranes and causing morphological changes to cells, but there was no obvious damage to DNA. In addition, OEO could effectively kill V. vulnificus in oysters at 25 °C, and the number of bacteria decreased by 48.2% after 0.09% OEO treatment for 10 h. The good inhibitory effect and bactericidal activity of OEO showed in this study, and the economy and security of OEO make it possible to apply OEO to control V. vulnificus contamination in oysters and other seafoods. View Full-Text

Research – Effect of Anolyte on S. Typhimurium and L. monocytogenes Growth in Minced Pork and Beef Cuts

MDPI

In this paper, anolyte is considered as a possible disinfectant for inhibiting the growth of bacteria in meat (beef cuts and minced pork). Meat cuts were contaminated with two concentrations of L. monocytogenes and S. Typhimurium, as these are the most common meat pathogens that are closely regulated by the EU, and treated with two different concentrations of anolyte: 20% for beef cuts and 18% for minced pork. Then, the total viable count (TVC), L. monocytogenes count and S. Typhimurium count were determined. In meat cuts and minced pork, anolyte was able to reduce TVC, S. Typhimurium and L. monocytogenes counts effectively, significantly decreasing L. monocytogenes and S. Typhimurium counts after spraying and throughout 29 days of incubation at 0–4 °C. TVC was reduced after spraying and for 10 days of incubation but later increased to be the same as before spraying with anolyte. Anolyte was effective when spraying beef cuts with a 20% solution for 60 s against pathogenic bacteria L. monocytogenes and Salmonella spp. and also when using it at a concentration of 18% from the minced meat mass. Initially, anolyte significantly decreased TVC, however during the storage period (10–29 days) TVC increased but remained significantly lower compared to control. Anolyte was effective in reducing L. monocytogenes and S. Typhimurium counts throughout the study, and after 29 days of incubation, these bacteria could not be detected in the samples treated with anolyte. View Full-Text

Research – Antifungal Preservation of Food by Lactic Acid Bacteria

MDPI

Aflatoxin

Image CDC

Fungal growth and consequent mycotoxin release in food and feed threatens human health, which might even, in acute cases, lead to death. Control and prevention of foodborne poisoning is a major task of public health that will be faced in the 21st century. Nowadays, consumers increasingly demand healthier and more natural food with minimal use of chemical preservatives, whose negative effects on human health are well known. Biopreservation is among the safest and most reliable methods for inhibiting fungi in food. Lactic acid bacteria (LAB) are of great interest as biological additives in food owing to their Generally Recognized as Safe (GRAS) classification and probiotic properties. LAB produce bioactive compounds such as reuterin, cyclic peptides, fatty acids, etc., with antifungal properties. This review highlights the great potential of LAB as biopreservatives by summarizing various reported antifungal activities/metabolites of LAB against fungal growth into foods. In the end, it provides profound insight into the possibilities and different factors to be considered in the application of LAB in different foods as well as enhancing their efficiency in biodetoxification and biopreservative activities. View Full-Text

Research – Phytic Acid against Clostridium perfringens Type A: A Food Matrix Study

MDPI

CDC Clost perf

This study evaluated the inhibitory effect of phytic acid (PA) on the spore germination and vegetative cells growth of Clostridium perfringens type A, as well as its effect in combination with maltodextrin (MD) in cooked sausages. The addition of 1% PA showed a satisfactory inhibition of spores’ germination and vegetative cells growth of C. perfringens in BHI media. The inhibitory effect of 1% PA on vegetative cells was similar to the additive sodium sorbate (SS) at 10%. Subsequently, a mixture of PA-MD (1:1; w/w) was evaluated for the inhibition of C. perfringens spores in cooked sausages. The PA-MD 1.5% and 2.5% had a similar performance to SS 10% and a similar or higher performance than 0.015% NO2 (p < 0.05). In an unprecedented way, the present study demonstrated that PA inhibited spore germination and vegetative cells growth of C. perfringens, highlighting its potential use as an alternative and natural preservative for the meat industry. View Full-Text

Research – Minimizing microbial contamination in primary production of fruits, vegetables, herbs and spices

Nestle

In the recent past, many plant-based ingredients, either processed or unprocessed, were found to be contaminated with pathogenic bacteria, viruses or parasites:–
In 2010, 272 individuals were infected with the bacterium Salmonella. This US outbreak was traced back to contaminated black pepper.–
In 2003, 640 people were sick and four died due to Hepatitis A virus in green onions. This was the most widespread Hepatitis A outbreak in the US.–
In 2015 in the US, 546 people were ill due to the parasite Cyclospora in fresh cilantro. Contamination was found to be caused by poor agricultural practices.
Where does the contamination at farm level come from?
Contamination can have several origins, these are the so-called “routes of microbial contamination”. Seven routes have been identified:
1. Growing field and adjacent land;
2. Animals;
3.Manure-based soil amendments;
4.Agricultural water;
5. Hygiene and human health;
6.Worker harvesting practices;
7.Equipment, premises and transportation.

See the full guide at the link above

USDA – Don’t Fumble Food Safety on Super Bowl Sunday

USDA

WASHINGTON, Feb. 3, 2022 — On February 13, millions of Americans will come together to watch Super Bowl LVI and feast on hot and cold snacks throughout the four-hour event. This uniquely American tradition scores big on entertainment, but it is also rife with opportunity for foodborne illness.

“As families and friends safely gather to watch the big game, keep food safety in mind. No matter who you’re rooting for, foodborne illness is a dangerous opponent we face during the game,” said Agriculture Secretary Tom Vilsack. “Millions of people get sick from food poisoning each year. Following guidance on keeping food at safe temperatures, proper handwashing and avoiding cross-contamination will protect you and your party guests.”

Unlike other food holidays when meals are often consumed within an hour, Super Bowl fans often snack on food throughout the game. Perishable foods, such as chicken wings, deli wraps and meatball appetizers, as well as cut fruit and vegetable platters, can only be left out for two hours before they become at risk of bacteria multiplying to dangerous levels. USDA recommends you put out small amounts of food and replenish it frequently.

Here are some food safety tips for Super Bowl Sunday:

#1 Remember Your Four Steps to Food Safety

  • Clean: Wash hands for 20 seconds before and after handling raw meat and poultry. Clean hands, surfaces and utensils with soap and warm water before cooking and after contact with raw meat and poultry. After cleaning surfaces that raw meat and poultry has touched, apply a commercial or homemade sanitizing solution (1 tablespoon of liquid chlorine bleach per gallon of water). Use hand sanitizer that contains at least 60 percent alcohol.
  • Separate: Use separate cutting boards, plates and utensils to avoid cross-contamination between raw meat or poultry and foods that are ready-to-eat.
  • Cook: Confirm foods are cooked to a safe internal temperature by using a food thermometer.
  • Chill: Chill foods promptly if not consuming immediately after cooking. Don’t leave food at room temperature for longer than two hours.

#2 Cook Your Food to a Safe Internal Temperature

  • Using a food thermometer, ensure you reach a safe internal temperature when cooking: meat (whole beef, pork and lamb) 145 F with a 3-minute rest; ground meats 160 F; poultry (ground and whole) 165 F; eggs 160 F; fish and shellfish 145 F; and leftovers and casseroles 165 F.
  • If chicken wings are on the menu, use a food thermometer on several wings to gauge the doneness of the entire batch. If one is under 165 F, continue cooking all wings until they reach that safe internal temperature.

#3 Avoid the Danger Zone

  • Bacteria multiply rapidly between 40 F and 140 F. This temperature range is called the Danger Zone.
  • Perishable foods, such as chicken wings, deli wraps and meatball appetizers, should be discarded if left out for longer than two hours. To prevent food waste, refrigerate or freeze perishable items within two hours.
    • Keep cold foods at a temperature of 40 F or below by keeping food nestled in ice or refrigerated until ready to serve.
    • Keep hot foods at a temperature of 140 F or above by placing food in a preheated oven, warming trays, chafing dishes or slow cookers.
  • Divide leftovers into smaller portions and refrigerate or freeze them in shallow containers which helps leftovers cool quicker than storing them in large containers.

#4 Keep Takeout Food Safe

  • If you order food and it’s delivered or picked up in advance of the big game, divide the food into smaller portions or pieces, place in shallow containers and refrigerate until ready to reheat and serve. You can also keep the food warm (above 140 F) in a preheated oven, warming tray, chafing dish or slow cooker.
  • When reheating food containing meat or poultry, make sure the internal temperature reaches 165 F as measured by a food thermometer.
  • If heating food in the microwave, ensure that contents are evenly dispersed. Because microwaved food can have cold spots, be sure to stir food evenly until the food has reached a safe internal temperature throughout.

RASFF Alerts – Animal Feed – Salmonella – Feeder Mice – Rapeseed Extraction Meal

RASFF

Salmonella spp. in rapeseed extraction meal from Germany in the Netherlands

RASFF

Salmonella detected in Feeder Mice from Lithuania in the UK, Poland and Netherlands

Research – Effect of phenolic compounds and cold shock on survival and virulence of Escherichia coli pathotypes

Wiley Online

Phenolic compounds (PC) affect many metabolic processes of microbes; however, there is no information about their effectiveness when these act in combination with low temperatures for the control of Escherichia coli pathotypes. In this study, four PC, (tannic acid [TA], gallic acid [GA], methyl gallate [MG], and epigallocatechin gallate [EG]) in combination with cold shock (CS, 10°C) were evaluated for their effect on growth, swarming motility, biofilm formation, and expression of selected virulence-related genes of E. coli pathotypes [enteropathogenic (EPEC), enterohemorrhagic (EHEC), and enterotoxigenic (ETEC)]. Sub-inhibitory concentrations of the PC were used alone (37°C) or in combination with CS. For CS assays, E. coli strains were grown at 37°C until mid-log phase and then subjected to 10°C for 4 hr. Membrane damage was determined by flow cytometry; swarming motility was measured on soft-LB agar, biofilm formation was analyzed by crystal violet staining, and gene expression of CS, biofilm, and swarming motility related-genes was determined by qPCR. Sub-inhibitory concentrations of the PC did not affect the viability of the strains. The combination of CS + TA provoked the highest (p ≤ .05) mortality in all pathotypes. CS + GA inhibited (100%) the motility of EHEC and ETEC. PC and CS + PC reduced (p ≤ .05) biofilm formation. The combination of PC and CS affected virulence factors and their gene expression of pathogenic E. coli presenting a novel alternative for its control in foods.

UK – Water quality – Risk assessments for Pseudomonas aeruginosa and other waterborne pathogens. Code of practice

BSI

CDC Pseudomonas

Overview

What is BS 8580-2 – Risk assessments for Pseudomonas aeruginosa about?

Our experts identified a lack of guidance on how to conduct risk assessments for Pseudomonas aeruginosa (PA) and other opportunistic waterborne pathogens other than Legionella. To fill that gap, BS 8580-2 is a new British Standard recommending a PA risk assessment process and supplying information and support on how to understand microbial hazards, prioritize actions and minimize risks.

Who is BS 8580-2 – Risk assessments for Pseudomonas aeruginosa for?

BS 8580-2 on risk assessments for pseudomonas aeruginosa applies in all types of healthcare provision, including hospitals, and care, nursing and residential homes, together with other settings where water systems and associated equipment can pose a risk. This can include in the educational, travel, industrial, leisure and beauty sectors, including health spas, nail bars and tattoo parlours.

Users of BS 8580-2 will be building and design engineers and architects; providers of fittings, outlets and components for water systems; installers and commissioners; risk assessors; regulatory bodies; building services engineers; water treatment consultants; travel, leisure and other relevant buildings owners and operators; and those responsible for the safe management of water systems, especially within leisure centres, schools, swimming pools, passenger vessels, spa pools, hot tubs etc.

BS 8580-2 will also interest clinicians, microbiologists, augmented care specialists and infection controllers in healthcare.

What does BS 8580-2 – Risk assessments for Pseudomonas aeruginosa cover?

BS 8580-2 gives recommendations and guidance on how to carry out risk assessments for pseudomonas aeruginosa (PA) and other waterborne pathogens whose natural habitat is within constructed water systems and the aqueous environment (autochthonous), rather than those present as a result of a contamination event. It includes those pathogens that can colonize and grow within water systems and the associated environment.

BS 8580-2 also covers risk assessments of distributed water systems and associated equipment, system components and fittings as well as above ground drainage systems. It covers PA risk assessment reviews and reassessments where a previous assessment has been undertaken and risk factors identified. It takes account of all relevant environmental and clinical factors and aspects of human behaviour leading to contamination events. It considers risk factors within the associated environment leading to conditions which can encourage the colonization and growth of waterborne pathogens and transfer of antibiotic resistance.

NOTE: BS 8580-2 does not cover risk assessments for Legionella spp.; these are covered in BS 8580-1, or risk assessments for enteric microorganisms derived from human or animal faecal contamination or sewage ingress.

Why should you use BS 8580-2 – Risk assessments for Pseudomonas aeruginosa?

You should use BS 8580-2 on risk assessments for pseudomonas aeruginosa because:

  • It plugs an information gap in relation to pseudomonas aeruginosa (PA) risk assessments, taking its unique additional considerations into account
  • It codifies the latest and most efficient approach to multidisciplinary PA risk assessments
  • Its recommended processes can be applied to other opportunistic waterborne pathogens
  • It can help healthcare providers demonstrate compliant risk management in respect of Dept of Health Guidance
  • It can help leisure sector organizations maintain compliance with their legal health and safety obligations
  • It can help users develop their expertise in risk assessment and strengthen organizational risk management

BS 8580-2 contributes to UN Sustainable Development Goal 3 on good health and well-being and Goal 6 on clean water and sanitation.