Category Archives: microbial contamination

Research – Detection of multiple naturally occurring Salmonella serotypes from commercial broiler carcasses with conventional methods

Wiley Online

Many laboratories sampling foods for Salmonella are interested only in presence or absence of Salmonella, so only one colony may be selected. The objectives of this study were to use two selective enrichment broths and two selective agar plating media for Salmonella recovery from naturally contaminated broiler carcass rinsates and evaluate these media combinations on Salmonella serotypes recovered from each carcass. Broiler carcasses (n = 52) from a commercial processing plant prior to chilling were rinsed with buffered peptone water and after incubation subcultured to gram‐negative and tetrathionate, and after inoculation to Rappaport Vassiliadis broth which was incubated and then streaked onto plates of Brilliant Green Sulfa and Xylose‐Lysine‐Tergitol‐4 agar. On 11/49 positive carcasses, both plating media yielded the same serotypes; for the other 38 positive samples different serotypes were found on the different plating media. Enrichment and plating media combinations influence the serotypes recovered and demonstrates bias even in a limited study such as this.

Research – Mode of action of nisin on Escherichia coli

nrc research 

Nisin is a class I polycyclic bacteriocin produced by the bacterium Lactococcus lactis, which is used extensively as a food additive to inhibit the growth of foodborne Gram-positive bacteria. Nisin also inhibits growth of Gram-negative bacteria when combined with membrane-disrupting chelators such as citric acid. To gain insight into nisin’s mode of action, we analyzed chemical–genetic interactions and identified nisin-sensitive Escherichia coli strains in the Keio library of knockout mutants. The most sensitive mutants fell into two main groups. The first group accords with the previously proposed mode of action based on studies with Gram-positive bacteria, whereby nisin interacts with factors involved in cell wall, membrane, envelope biogenesis. We identified an additional, novel mode of action for nisin based on the second group of sensitive mutants that involves cell cycle and DNA replication, recombination, and repair. Further analyses supported these two distinct modes of action.

Research – Indoor Particulate Matter From Smoker Homes Induces Bacterial Growth, Biofilm Formation, and Impairs Airway Antimicrobial Activity. A Pilot Study

Frontiers

Background: Particulate matter (PM) air pollution causes deleterious health effects; however, less is known about health effects of indoor air particulate matter (IAP).

Objective: To understand whether IAP influences distinct mechanisms in the development of respiratory tract infections, including bacterial growth, biofilm formation, and innate immunity. Additionally, we tested whether IAP from Iowa houses of subjects with and without recent respiratory exacerbations recapitulated the National Institute of Standards and Technology (NIST) IAP findings.

Methods: To test the effect of NIST and Iowa IAP on bacterial growth and biofilm formation, we assessed Staphylococcus aureus growth and Pseudomonas aeruginosa biofilm formation with and without the presence of IAP. To assess the effect of IAP on innate immunity, we exposed primary human airway surface liquid (ASL) to NIST, and Iowa IAP. Lastly, we tested whether specific metals may be responsible for effects on airway innate immunity.

Results: NIST and Iowa IAP significantly enhanced bacterial growth and biofilm formation. NIST IAP (whole particle and the soluble portion) impaired ASL antimicrobial activity. IAP from one Iowa home significantly impaired ASL antimicrobial activity (p < 0.05), and five other homes demonstrated a trend (p ≤ 0.18) of impaired ASL antimicrobial activity. IAP from homes of subjects with a recent history of respiratory exacerbation tended (p = 0.09) to impair ASL antimicrobial activity more than IAP from homes of those without a history respiratory exacerbation. Aluminum and Magnesium impaired ASL antimicrobial activity, while copper was bactericidal. Combining metals varied their effect on ASL antimicrobial activity.

Conclusions: NIST IAP and Iowa IAP enhanced bacterial growth and biofilm formation. ASL antimicrobial activity was impaired by NIST IAP, and Iowa house IAP from subjects with recent respiratory exacerbation tended to impair ASL antimicrobial activity. Individual metals may explain impaired ASL antimicrobial activity; however, antimicrobial activity in the presence of multiple metals warrants further study.

Research – Assessment of the potential of Arabic gum as an antimicrobial and antioxidant agent in developing vegan “egg‐free” mayonnaise

Wiley Online

The main factors affecting the spoilage of mayonnaise are lipid oxidation and microbial contamination. Therefore, the investigation was carried out to estimate the antimicrobial and antioxidant properties of the aqueous extract of the Arabic gum (AG). The effect of the addition of AG powder on physical–chemical and sensory properties has been evaluated in different percentages of 25, 50, 75, and 100 into mayonnaise. At the highest concentration of AG 20 mg/ml, the DPPH result represented high antioxidant activity at 92.13%. AG had inhibitory effects on gram‐negative and gram‐positive bacteria, with Staphylococcus aureus and Bacillus subtilis being the most susceptible bacteria. The use of AG as an egg substitute in mayonnaise has been shown to have a great effect on physical–chemical properties. All mayonnaise samples were sensory acceptable, particularly vegan mayonnaise (100% AG) and still acceptable for consumption at 5°C for 5 months of storage. AG could be considered an additive with significant emulsifier properties, antioxidant, and antimicrobial activities. Therefore, AG is a good choice to produce new vegetarian products for consumers who are unable to eat egg‐based foods.

RASFF Alert – Animal Feed – Aflatoxin – Shelled Peanuts

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RASFF – aflatoxins (B1 = 25.2 µg/kg – ppb) in shelled peanuts from the United States in the UK

RASFF Alerts – Animal Feed – Salmonella – Fish Meal – Organic Rape Cake

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RASFF – Salmonella enterica ser. Oranienburg (in 5 out 5 samples) in fish meal from the United States in Greece

RASFF – Salmonella enterica ser. Oranienburg (presence /25g) in fishmeal from the United States in Greece

RASFF – Salmonella enterica ser. Oranienburg (present /25g) in fish meal from the United States in Greece

RASFF – Salmonella enterica ser. Senftenberg (presence /25g) in organic rape cake expeller from France in Finland

RASFF – Salmonella enterica ser. Oranienburg (presence /25g) in fishmeal from the United States in Greece

Europe -Salmonellosis – Annual Epidemiological Report for 2017

ECDC

Salmonellosis is the second most commonly reported gastrointestinal infection and an important cause of foodborne outbreaks in the EU/EEA. In 2017, 92 649 laboratory-confirmed cases were reported of which 156 were fatal. The EU/EEA notification rate was 19.6 cases per 100 000 population. Salmonellosis notification rates have stabilised in the last five years after a long period marked by a declining trend. The notification rate was highest in young children 0−4 years with 94.1 cases per 100 000 population, eight times higher than in adults 25–64 years.

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Research -Impacts of broadband and selected infrared wavelength treatments on inactivation of microbes on rough rice.

Wiley Online

This study investigated the effects of broadband and selected infrared (IR) wavelength treatments of rough rice on microbial inactivation. Rough rice was treated at different IR wavelengths and product‐to‐emitter distances (110, 275, and 440 mm) followed by tempering at 60°C for 4 hr. The total mold and aerobic plate counts (APC) on non‐treated and treated samples were determined. Significant total mold reductions of 1.14 and 3.11 log CFU/g were obtained after IR heating using broadband and selected wavelengths, respectively (p < .05). The most significant reduction of APC using selected IR wavelength was 1.09 log CFU/g; the broadband IR wavelength had no effect on the mean APC. The IR treatments followed by tempering step resulted in greater reductions of total mold counts and APC (4.03 and 3.50 log CFU/g) in comparison to IR treatments without tempering (3.11 and 1.09 log CFU/g). Overall, bacteria showed more resistance to IR treatments than molds.

Research – Researchers find spread of bacteria in seafood likely impacted by trade

Food Safety News

A Centers for Disease Control and Prevention study has found that international trade of shellfish might be involved in the dispersal of Vibrio parahaemolyticus populations into the United States and Spain. The study found that severe weather, such as El Niño conditions in Peru, provide ideal conditions for the proliferation of Vibrio parahaemolyticus, Vibrio alginolyticus and Vibrio vulnificus.

The CDC reports that compared to other major foodborne illnesses, Vibrio parahaemolyticus infections have been steadily increasing. Vibrio parahaemolyticus is the leading cause of seafood-related bacterial infections globally. The CDC estimates that the average annual incidence of all Vibrio infections increased 54 percent during 2006–2017. Vibrio parahaemolyticus is believed to be responsible for about 35,000 human infections each year in the United States and has been the leading cause of foodborne infections in China since the 1990s.

The transition of V. parahaemolyticus disease from a regional to a global pathogen is connected to the emergence of isolates with epidemic potential.

Research – Stressed-out dust is sharing antibiotic resistance genes

Northwestern

First study to show indoor dust bacteria have transferrable antibiotic resistance genes.

A new Northwestern University study is the first to find that bacteria living in household dust can spread antibiotic resistance genes. Although most bacteria are harmless, the researchers believe these genes could potentially spread to pathogens, making infections more difficult to treat.

“This evidence, in and of itself, doesn’t mean that antibiotic resistance is getting worse,” said Northwestern’s Erica Hartmann, who led the study. “It’s just one more risk factor. It’s one more thing that we need to be careful about.”