Category Archives: Food Microbiology Research

Research – Assessing the microbiological quality of raw goats’ and ewes’ tank milk samples in Switzerland

Posted on December 16, 2019 by | Leave a comment

Science Direct

In recent years, popularity of raw milk has increased in many industrialised countries.

This study (i) enumerated total viable counts (TVC) and Escherichia coli counts, (ii) assessed prevalence of Staphylococcus (S.) aureus, Salmonella spp. and STEC, (iii) screened for methicillin resistant S. aureus (MRSA) and extended-spectrum β-lactamases (ESBL)-producing Enterobacteriaceae in sheep and goat tank milk samples collected throughout Switzerland and (iv) provided further strain characteristics on isolated pathogens and MRSA. One hundred and twenty-three tank milk samples from 116 farms were analysed. The median TVC was 3.8 log cfu mL-1. E. coli was detected in 16 (13.0%) and S. aureus in 18 (14.6%) samples. Polymerase chain reaction for stx genes was positive in 14 (11.4%) samples. MRSA were isolated from 4 (3.3%) samples. Salmonella spp. and ESBL-producing Enterobacteriaceae were not isolated.

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Posted in Enterobacteriaceae, ESBL, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, microbial contamination, Microbiology, MRSA, Research, Salmonella, Staphylococcus aureus, STEC, STEC E.coli, Uncategorized

Research – Simultaneous Effects of UV-A and UV-B Irradiation on the Survival of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in Buffer Solution and Apple Juice

Posted on December 15, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

The objective of this study was to evaluate the efficacy of simultaneous UV-A and UV-B irradiation (UV-A+B) for inactivating Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in both phosphate-buffered saline (PBS) and apple juice. A cocktail of the three pathogens was inoculated into PBS and apple juice, and then the suspensions were irradiated with UV lamps of 356 nm (UV-A) and 307 nm (UV-B). Significant (P < 0.05) log reductions of the three pathogens in PBS and apple juice were observed after a maximum dose of UV-B alone or the UV-A+B treatment, but few reductions were observed upon UV-A treatment alone. At all irradiation times, antagonistic effects were observed for the application of UV-A+B against in E. coli O157:H7, Salmonella Typhimurium, and L. monocytogenes in PBS and apple juice. The degree of antagonistic effect in apple juice was greater than that in PBS. The results of this study suggest that the combined treatment of commercial UV-A and UV-B lamps would be impractical for disinfecting juice products.

HIGHLIGHTS

  • Antimicrobial effect of UV-A+B irradiation in PBS and apple juice was investigated.

  • UV-A+B irradiation was antagonistic for inactivating pathogens in the PBS and juice.

  • The degree of antagonistic effect in apple juice was greater than that in PBS.

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

Research – Microbial Diversity in Bushmeat Samples Recovered from the Serengeti Ecosystem in Tanzania

Posted on December 15, 2019 by | Leave a comment

Nature.com

Bushmeat, the meat and organs derived from wildlife species, is a common source of animal protein in the diets of those living in sub-Saharan Africa and is frequently associated with zoonotic spillover of dangerous pathogens. Given the frequent consumption of bushmeat in this region and the lack of knowledge about the microbial communities associated with this meat, the microbiome of 56 fresh and processed bushmeat samples ascertained from three districts in the Western Serengeti ecosystem in Tanzania was characterized using 16S rRNA metagenomic sequencing. The results show that the most abundant phyla present in bushmeat samples include Firmicutes (67.8%), Proteobacteria (18.4%), Cyanobacteria (8.9%), and Bacteroidetes (3.1%). Regardless of wildlife species, sample condition, season, or region, the microbiome is diverse across all samples, with no significant difference in alpha or beta diversity. The findings also suggest the presence of DNA signatures of potentially dangerous zoonotic pathogens, including those from the genus Bacillus, Brucella, Coxiella, and others, in bushmeat. Together, this investigation provides a better understanding of the microbiome associated with this major food source in samples collected from the Western Serengeti in Tanzania and highlights a need for future investigations on the potential health risks associated with the harvesting, trade, and consumption of bushmeat in Sub-Saharan Africa.

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Posted in Bacillus, food contamination, Food Hygiene, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Pathogen, Food Safety, Food Testing, Research, Uncategorized

Research – Evaluation of Inactivation of Murine Norovirus in Inoculated Shell Oysters by High Hydrostatic Pressure Treatment

Posted on December 14, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

One of the major foods causing norovirus gastroenteritis is bivalve shellfish, such as oysters. Depuration and relaying methods have been used to control norovirus. However, these methods may be inadequate to control norovirus gastroenteritis. The present study aimed to investigate the effectiveness of high hydrostatic pressure (HHP) treatment in controlling norovirus in shelled oysters, by evaluating the inactivating effect of HHP on murine norovirus strain 1 (MNV-1) inoculated into a buffer, oyster homogenate, and shelled oysters. First, MNV-1 was inoculated (infectivity of 4.5 log PFU/mL) into the buffer and oyster homogenate, with a pH of 6.3 and salinity (NaCl) of 1.5%, mimicking the habitats of the Pacific oyster (Crassostrea gigas). HHP treatment at 100, 200, 275, and 300 MPa for 2 and 5 min was conducted at an initial temperature of 0 or 5°C. The infectivity of MNV-1 in both the buffer and the oyster homogenate was lower when the initial temperature was 0°C. In the buffer, the infectivity of MNV-1 decreased to 1.8 log PFU/mL after HHP treatment (200 MPa for 5 min at 0°C), and the inactivating effect was higher in the buffer than in the oyster homogenate. MNV-1 was inoculated into shelled oysters (4.8 log PFU per oyster), and HHP treatment was done at 275, 300, and 350 MPa for 5 min at the initial temperature of 0°C. The infectivity of MNV-1 decreased to 2.8 log PFU per oyster after HHP treatment at 275 MPa for 5 min. The results indicate that the inactivating effect of HHP treatment varies, depending on the medium surrounding the viral particles. Inactivation was best in buffer, followed by oyster homogenate and shelled oysters. The data could inform the development of methods to control norovirus in oysters.

HIGHLIGHTS

  • HHP inactivation of MNV-1 was more pronounced at 0°C than at 5°C.

  • Inactivation differed, depending on the medium surrounding the virus.

  • HHP at 275 MPa for 5 min at 0°C inactivated MNV-1 inoculated in shucked oysters.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Technology, Food Virus, microbial contamination, Microbiology, Norovirus, Research, Technology, Uncategorized, Virus

Research -Prevalence and Genetic Analysis of Salmonella enterica from a Cross-Sectional Survey of the New Zealand Egg Production Environment

Posted on December 14, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Epidemiological evidence suggests that Salmonella on New Zealand eggs is not an important pathway for human salmonellosis. However, robust nationally representative data for Salmonella contamination of eggs is not available to support this. To better understand the exposure of New Zealand commercial eggs to Salmonella, a cross-sectional survey collected data on prevalence and serotypes of Salmonella in the feed, laying sheds (feces, dust, and boot or manure belt swabs), and packhouses (egg contact surfaces) of New Zealand commercial egg layer farms. Salmonella was not detected on 16 of 28 surveyed farms, and 4 farms had only one positive sample. Of the 43 (13.3%) of 323 Salmonella-positive samples, dust samples had the highest prevalence (19 of 67, 28.4%), followed by boot or manure belt swabs (11 of 67, 16.4%), feces (7 of 67, 10.4%), packhouse egg contact surfaces (5 of 87, 5.7%), and feed (1 of 33, 3.0%). A significantly higher prevalence was from caged (33 of 75, 44.0%; P < 0.001) compared with cage-free (4 of 126, 3.2%) systems, yet multiple practices differ between laying systems, which could influence prevalence. Salmonella-positive packhouse samples were only identified on the three farms with the highest laying shed prevalence, and isolates were genetically related (as determined by single nucleotide polymorphism analyses) suggesting cross-contamination between the laying shed and packhouse surfaces. Serotypes isolated included Salmonella Infantis, Salmonella Thompson, Salmonella Typhimurium, Salmonella Anatum, and Salmonella Mbandaka. Importantly, Salmonella Enteritidis, which causes egg-associated outbreaks internationally, was not isolated. Genomic comparisons of isolates supported the presence of a common contamination source in the shed and farm environments rather than multiple sporadic contamination events. This survey establishes a benchmark of Salmonella prevalence and types in the New Zealand egg production environment and provides a reference point for assessing the impact of changes to practices on Salmonella prevalence.

HIGHLIGHTS

  • Salmonella prevalence was lower than from similar international surveys.

  • The highest prevalence was from pooled dust samples.

  • Salmonella occurred on packhouse egg contact surfaces from high-prevalence farms.

  • Isolates from the same farm, laying shed, and packhouse were genetically related.

  • Isolates included common New Zealand serotypes; Salmonella Enteritidis was not found.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, microbial contamination, Microbiology, Research, Salmonella, Uncategorized

Europe – Salmonella the most common cause of foodborne outbreaks in the European Union

Posted on December 13, 2019 by | Leave a comment

ECDC

Nearly one in three foodborne outbreaks in the EU in 2018 were caused by Salmonella. This is one of the main findings of the annual report on trends and sources of zoonoses published today by the European Food Safety Authority (EFSA) and the European Centre for Disease Prevention and Control (ECDC).

In 2018, EU Member States reported 5 146 foodborne outbreaks affecting 48 365 people. A foodborne disease outbreak is an incident during which at least two people contract the same illness from the same contaminated food or drink.

Slovakia, Spain and Poland accounted for 67% of the 1 581 Salmonella outbreaks. These outbreaks were mainly linked to eggs.

 “Findings from our latest Eurobarometer show that less than one third of European citizens rank food poisoning from bacteria among their top five concerns when it comes to food safety. The number of reported outbreaks suggests that there’s room for raising awareness among consumers as many foodborne illnesses are preventable by improving hygiene measures when handling and preparing food” said EFSA’s chief scientist Marta Hugas.

Salmonellosis was the second most commonly reported gastrointestinal infection in humans in the EU (91 857 cases reported), after campylobacteriosis (246 571).

Shiga toxin-producing E. coli (STEC) has become the third most common cause of foodborne zoonotic disease with 8 161 reported cases – replacing yersiniosis with a 37% increase compared to 2017. This may be partly explained by the growing use of new laboratory technologies, making the detection of sporadic cases easier.

Of the zoonotic diseases covered by the report, listeriosis accounts for the highest proportion of hospitalised cases (97%) and highest number of deaths (229), making it one of the most serious foodborne diseases.

The number of people affected by listeriosis in 2018 is similar to 2017 (2 549 in 2018 against 2 480 the previous year). However, the trend has been upward over the past ten years.

The report also includes data on Mycobacterium bovis, Brucella, Yersinia, Trichinella, Echinococcus, Toxoplasma, rabies, Coxiella burnetii (Q fever), and tularaemia.

Read the report

Publication

The European Union One Health 2018 Zoonoses Report

Surveillance report – 

This report of the European Food Safety Authority and the European Centre for Disease Prevention and Control presents the results of zoonoses monitoring activities carried out in 2018 in 36 European countries (28 Member States (MS) and 8 non-MS).

The European Union One Health 2018 Zoonoses Report – EN – [PDF-14.15 MB]
e.

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Posted in E.coli, E.coli O157, E.coli O157:H7, food bourne outbreak, food contamination, food death, Food Hygiene, Food Illness, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Pathogen, Food Poisoning, food recall, Food Safety, Food Safety Alert, Food Testing, Food Toxin, foodborne disease, Foodborne Illness, foodborne outbreak, foodbourne outbreak, Listeria, Listeria monocytogenes, Research, Salmonella, STEC, STEC E.coli, Uncategorized

Research – Preventative care: Increasing Hepatitis A vaccinations among food service workers

Posted on December 12, 2019 by | Leave a comment

Food Safety News 

Thesis: Over the past three years, there has been an ongoing outbreak of Hepatitis A in the United States although it is the only foodborne disease that has a vaccination. Mandating vaccinations to food service workers is essential to reduce the spread of Hepatitis A, especially since outbreaks involving food handlers are in the public eye. 

Background & Analysis: It is estimated that in the United States alone there are 48 million cases of foodborne illness annually. Out of these 48 million, 128,000 are hospitalized and 3,000 people die. The CDC recommends to the general public that the best way to prevent Hepatitis A is through vaccination, but not have explicitly stated that food service workers should be administered the vaccination. While food service workers are not traditionally designated as having an increased risk of Hepatitis A transmission, they are not free from risk. Additionally, 24% of Hepatitis A cases are asymptomatic which means a food-handler carrying the virus can unknowingly transmit the disease to a consumer. Historically, when an outbreak occurs local health departments start administering the vaccine for free or at a reduced cost. The funding from these vaccinations is through taxpayer dollars. 

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Posted in food handler, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Virus, Hand Washing, Hepatitis A, microbial contamination, Microbiology, Uncategorized, Virus

Germany – No impact on Campylobacter contamination from new rules

Posted on December 12, 2019 by | Leave a comment

Food Safety News

 

Stricter rules on Campylobacter have not yet led to a decrease in contamination based on figures from a German agency.

Almost a quarter of carcasses in the country had Campylobacter counts of more than 1,000 colony forming units per gram (cfu/g) in 2018, according to the Federal Office of Consumer Protection and Food Safety (BVL).

The process hygiene criterion of no more than 1,000 cfu/g on broiler carcasses at slaughterhouse level was introduced from January 2018 across the EU to determine the presence of Campylobacter spp. in the poultry meat chain. The aim is to prevent poultry meat with high levels of Campylobacter per gram being sold. If high levels are detected, the food business must improve hygiene.

In 2017, prior to introduction of the legislation, 22.7 percent of carcasses in Germany exceeded the levels. In 2018, the rate remained virtually unchanged at 22.6 percent. BVL said ongoing zoonotic monitoring will show to what extent the introduced threshold leads to an improvement in the situation.

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Posted in Campylobacter, Food Micro Blog, Food Microbiology Research, Food Safety, microbial contamination, Microbiology, Research, Uncategorized

Research – Evaluating the Antimicrobial Efficacy of White Mustard Essential Oil Alone and in Combination with Thymol and Carvacrol against Salmonella

Posted on December 11, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

It is estimated that nontyphoidal Salmonella causes approximately 1 million illnesses and 378 deaths per year in the United States. Reduction of Salmonella-related foodborne infections can be achieved through application of food antimicrobials. Essential oils in combination with other antimicrobials can be added to food products to reduce the levels of the organism below the infectious dose for healthy individuals. The purpose of this study was to investigate the antimicrobial efficacy of white mustard essential oil (WMEO) against serovars of Salmonella and its potential to be used with carvacrol or thymol to control Salmonella. Results showed that WMEO at the highest concentration of 0.84% (v/v) compared with the positive control had approximately a 6- to 7-log reduction for all serovars. It was found that no difference in susceptibility existed among the serovars tested (P > 0.05). In addition, the MICs were determined to be 0.5, 0.02, and 0.02% for WMEO, carvacrol, and thymol, respectively, against Salmonella Typhimurium. The fractional inhibitory concentration index was calculated. A score of 1 indicated an additive effect occurred when WMEO was combined with thymol or carvacrol. Combining WMEO with carvacrol or thymol indicated that the concentration of individual essential oils needed to inhibit Salmonella can be reduced using these combinations and warrants further study to determine potential use in controlling Salmonella in commercial food products.

HIGHLIGHTS

  • WMEO showed no significant difference in antimicrobial activity between Salmonella serovars.

  • The MIC of WMEO against Salmonella Typhimurium was 0.5%.

  • Combination with thymol or carvacrol had an additive effect on the antimicrobial activity of WMEO.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Technology, microbial contamination, Microbiology, Research, Salmonella, Technology, Uncategorized

Research – Occurrence and Abundance of Pathogenic Vibrio Species in Raw Oysters at Retail Seafood Markets in Northwestern Mexico

Posted on December 10, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Seafood has frequently been associated with foodborne illness because pathogens are easily introduced during seafood cultivation, handling, and processing. Vibrio parahaemolyticus and Vibrio cholerae are human pathogens that cause gastroenteritis and cholera, respectively, and Vibrio vulnificus can cause fatal wound infections and septicemia. However, information about the occurrence of these pathogens in oysters from the Pacific coast of Mexico is limited to V. parahaemolyticus. In the present study, we evaluated the presence and abundance of these three Vibrio species in 68 raw oysters (Crassostrea corteziensis) obtained from retail seafood markets in Sinaloa, Mexico. The most probable number (MPN)–PCR assay was used for amplification of the tlh (thermolabile hemolysin), ompW (outer membrane protein), and vvhA (hemolytic cytolysin) genes that are specific to V. parahaemolyticus, V. cholerae, and V. vulnificus, respectively. All oyster samples were positive for at least one Vibrio species. V. parahaemolyticus, V. cholerae, and V. vulnificus prevalences were 77.9, 8.8, and 32.3% overall, respectively, and most species were present in all sample periods with increased prevalence in period 3. The tdh (thermostable direct hemolysin) gene was detected in 30.1%, trh (TDH-related hemolysin) was detected in 3.7%, and tdh/trh was detected in 7.5% of the total tlh-positive samples (53 of 68), whereas the pandemic serotype O3:K6 (orf8 positive) was detected in only 1 sample (1.8%). The total prevalence of tdh and/or trh was 41.5%. In none of the samples positive for V. cholerae were the cholera toxin (ctxA) and cholix (chxA) toxigenic genes or the rfb gene encoding the O1 and O139 antigens amplified, suggesting the presence of non-O1 non-O139 V. cholerae strains. Our results clearly indicated a high prevalence of pathogenic Vibrio species in raw oysters from retail seafood markets in Mexico. Consumption of these raw oysters carries the potential risk of foodborne illness, which can be limited by cooking.

HIGHLIGHTS

  • V. parahaemolyticus, V. cholerae, and V. vulnificus were prevalent in raw oysters from Mexico.

  • The tdh and trh genes and the pandemic O3:K6 serotype were detected in raw oysters.

  • The ctxA and chxA genes, and O1/O139 serotypes were absent from V. cholerae–positive samples.

  • The consumption of raw oysters represents a health risk for Vibrio infections.

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Posted in Contaminated water, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, microbial contamination, Microbiology, Research, Uncategorized, Vibrio, Vibrio cholera, Vibrio parahaemolyticus, Vibrio vulnificans, Vibrio vulnificus, Water, water microbiology