This study investigated the prevalence of Staphylococcus aureus in raw milk dairy products handcrafted in traditional alpine small-scale farms, and characterised the enterotoxigenicity and resistance ...to methicillin. Among the analysed samples, 69% exceeded the international microbiological recommendations. The highest counts were observed for cheese or fatty products (~106 cfu/g). Conversely, lower contamination levels concerned raw milk and whey cheese (~102 cfu/g). A total of 163 S. aureus isolates were collected, and the prevalence of MRSA was low (1.7%) but not negligible. The finding of enterotoxins genes in 67% of the isolates is of concern for the public health.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract
Background
The raise in global food trading showed an increase in allergic cases in Europe. Ethnic, novel and hidden food enhanced the probability of consumers to adverse events. The demand ...for allergens-free food grew with the need to be informed on the ingredients content. EU Reg. 1169/2011, details the products causing allergies or intolerances that must be indicated on the label if present. This work studied the prevalence of suspected allergens into apparently compliant food and environmental samples, aiming to verify their safety.
Methods
Totally, 1611 foodstuffs and 128 swabs were received from January 2022 to April 2023. They were independently tested for gluten, milk, egg, mustard, peanut, pistachio, sesame, soy or hazelnut. Commercial ELISA kits were used according to manufacturers’ instructions. Non-compliance to gluten was >20 ppm, and for the other allergens it was “presence” above the limit of detection.
Results
Data showed 46 non-compliant samples (2.6%): 37 foodstuffs (2.1%) and 9 swabs (0.5%). Of these, 16 were irregular for gluten (34.8%) and 14 (9 swabs, 5 food) for egg (30.4%); 9 contained milk (19.5%), 4 (8.7%) hazelnut, 2 (4.3%) soy and 1 (2.2%) peanut. No positives for other allergens. The most tested parameters were gluten (85%) and milk (10%).
Conclusions
The frequency of food allergy in Europe has been increasingly reported. In this study, 97.4% of samples complied with the label and were safe for allergic consumers. Clients were highly sensitive to gluten, egg, milk, soy and nut-free products. Considering the importance of food for human health and the increase in illness cases, checking of compliance to the rules is important.
Key messages
• The majority of allergens can affect seriously allergic consumers (also death), even if present in traces. A continuous surveillance is very important to prevent risks for sensitive consumers.
• The foodstuffs collected in this survey are mainly safe for allergic people.
Background
In recent decades, the celiac disease showed a gradual increase in prevalence. Therefore, there was a raised demand of gluten-free products. EU Reg. 1169/2011 states that 20 mg.kg-1 (ppm) ...is the maximum gluten content in food for celiac people, and that "gluten-free" labelling must be put on compliant food packages. This work is a study on different food categories, aiming at verifying the safety of analyzed samples.
Methods
Totally, 4615 gluten-free-labelled specimens were collected from January 2019 to April 2022 (pasta, 2944; cured meat, 566; flours/bakery, 489; sweets, 125 and other matrices, 491). A commercially available E.L.I.S.A. kit, according to the AOAC 2012.01-2016 method, was used to quantify gluten.
Results
In 97% of samples (4475) the gluten content was <5 ppm (lower LOD), and in 2.4% (112) it was between 5 ppm and <20 ppm. In the remaining 0.6% (28), the gluten concentration was ≥20 ppm. Of these, 0.32% (15) were between 20 and <80 ppm (upper LOD), and 0.28% (13) ≥80 ppm.
Conclusions
The increased prevalence of celiac disease and the consumers' perception that a gluten-free diet gives benefits, lead to a greater demand of gluten-free products. In this study, 99.4% of samples were compliant with the gluten-free labelling and safe for celiac consumers. The 0.32% had a gluten content between 20 and 80 ppm, still considered "compliant", according to the EU Reg. 828/2014 that defines as very low gluten containing (thus edible for some celiac groups), those products with a gluten content <100 ppm. Only 0.28% of samples was non-compliant (≥80 ppm). However, the authors accounted irregular those foods with ≥20 ppm. Considering the importance of these products in the daily diet, and the increasing probability to get sick by individuals, the study of their compliance to the law limits results to be important.
Key messages
* A continuous surveillance of gluten-free-labelled food products is very important to prevent risks for celiac consumers.
* The foodstuffs distributed in the two considered regions are mainly safe for celiac patients.
Background
Listeria monocytogenes is a widespread foodborne pathogen that causes listeriosis, a human infection with low morbidity but high mortality. Internalin A (InlA), a L. monocytogenes ...virulence factor, has a key role in the invasion of human intestinal epithelium through the interaction with E-cadherin receptor. Truncated InlA caused by premature stop-codons (PMSC) have been correlated with attenuated virulence. To date, 29 mutations leading to a PMSC have been reported. In this study, we identified a rare PMSC mutation widespread in isolates from the production chain of the Gorgonzola and Taleggio PDO cheeses.
Methods
Within an ongoing monitoring plan for the characterization of L. monocytogenes, a total of 81 isolates collected in Lombardy (Northern Italy) from food, food processing environments, and clinical cases, between 2013-2021, were characterized using multilocus sequence tying (MLST) and then screened for the presence of PMSC by sequencing the 2400 pb inlA gene.
Results
A mutation leading to PMSC was identified on the position 277 (PMSC mutation type 26). To date, this mutation has been reported only on a CC7 strain from a clinical case. In our study, all isolates harbouring this mutation (n = 21) belong to ST325 (CC31, serotype 1/2a). Among these, 86% (n = 18) belong to the production chain of the Gorgonzola and Taleggio PDO cheeses.
Conclusions
To the best of our knowledge, this is the first report of PMSC mutation type 26 on food and environmental isolates. Although PMSC 26 is rarely found worldwide, our findings suggest that ST325 with this mutation is widespread in the production chain of the two PDO cheeses, and the presence of this PMSC may be correlated with the low incidence of ST325 clinical cases.
Key messages
A rare mutation leading to truncated InlA has been identified in a cluster of isolates correlated to the production chain of two PDO cheeses.
Truncated inlA is suggestive of adaptation to the niche to the detriment of virulence.
Abstract
Background
The importance of human milk in infants’ diets is well-known in the medical community. Unfortunately, breastfeeding isn't always possible for various reasons, human milk donation ...represents the main solution to this problem. The donated milk goes through a pasteurization treatment (62.5 °C for 30 minutes). Before consumption, the milk is tested to analyze the microbiological safety aspect, specifically: the protocol of a North Italian bank, provides for the total count of microorganisms and of Bacillus Cereus. The presence of B. Cereus in pasteurized milk samples has been witnessed in the last few years. B. Cereus infections in infants have consistently been reported and banked human milk could be one of the possible sources. This work aims to study the prevalence of B. Cereus in banked human milk sampled before and after pasteurization treatment.
Methods
Between 2020 and 2023 we tested 1055 samples, before and after the pasteurization treatment. The enumeration of B. cereus is performed in accordance with ISO 7932:2004. 100 µL of pure raw milk and two consecutive decimal dilutions in buffered peptone water were seeded on Bacillus cereus Agar (BCA) at 30° for 24h-48h. B. Cereus strains isolated were typed using the hemolysis test and BCA.
Results
We found 46 samples positives for B. Cereus from 1055 samples analyzed before the heat treatment. The number increased to 57 in the pasteurized samples. These data are confirmed by the typing of the isolated strains from the human milk.
Conclusions
The 4% of not pasteurized milk is discarded due to B. Cereus presence, and the rate increase to 5% in pasteurized milk. This information suggests that the heat treatment isn't capable to inhibit all the B. Cereus, and the increase of B. Cereus from not pasteurized to pasteurized need to be studied.
Key messages
• B. Cereus represents one of the main causes of noncompliance in banked human milk.
• Implementation of preventive/corrective actions is needed to prevent the contaminations led by the operators.
Abstract
Background
Bacillus cereus, responsible for 1.4%-12% of all food poisoning outbreaks worldwide, produces several virulence factors, including toxins which are mainly found in raw and ...processed food, as starch-based and dairy products. It can cause two types of gastrointestinal diseases: emetic form, with nausea and vomiting which appears as soon as after food consumption, and diarrheal form, with abdominal cramps, which occurs after 8-16 h. Moreover, B. cereus is the most common pathogen in pasteurized human milk, a precious aid in neonatal care. The aim of this study was to investigate the prevalence of B. cereus toxins kinds using WGS and to detect in silico sequence types (ST) in isolates from food and human milk.
Methods
During B. cereus routine surveillance in Lombardy (Italy), a total of 41 isolates were collected from food (n = 16) and donor breast milk (n = 25) between 2022-2023, and then analysed with WGS. Libraries were prepared using the Illumina DNA Prep Kit and WGS was performed on the Illumina MiSeq. Using the BTyper tool, for each sample emetic and diarrheal toxins were identified and ST was assigned.
Results
All 41 isolates had at least one diarrheal toxin, specifically the nonhemolytic enterotoxin was found in all the isolates, the cytotoxin K was detected in 37% of isolates, and the hemolysin BL in 32%. Instead, the emetic toxin was found in only 3 samples isolated from food. Using in silico MLST, different STs were found with a higher prevalence of ST26 and ST144.
Conclusions
Diarrheal toxins were detected in all samples underling that B. cereus food infections play an important role in the public health and in the food industry. These aspects are even more significant when the pathogen is isolated from human breast milk, as it can induce severe infections in newborns.
Key messages
• The presence of B. cereus toxins in food and human milk underlines the importance of its ongoing monitoring and analysis.
• Human breast milk has a high risk of B. cereus contamination which is the most frequent cause for its discarding.
Staphylococcus aureus is able to produce enterotoxins causing staphylococcal food poisoning, and is frequently harboured by dairy products. Also, S. aureus is able to form biofilm in the production ...environment, enhancing the risk of food contamination. The ability of 49 S. aureus isolates from the dairy production chain to form biofilm aim was tested, and their genetic diversity in terms of population structure and presence of genes involved in biofilm formation or enterotoxins production was explored. The majority of the genotypes found were generally bovine associated; however, some have been also reported frequently in human clinical cases. Two isolates were methicillin-resistant. In total, 38.7% of the isolates were biofilm producers, and among them 47.3%, 42.1% and 10.5% exhibited weak, moderate, or strong biofilm-forming ability, respectively. In total 68% of the biofilm producing isolates were also positive for enterotoxins genes, raising concerns for consumer safety.
Abstract
Background
Norovirus is an enteric virus with foodborne transmission. Bivalve shellfish are a main source of infections and outbreaks, which in the last years are showing an increasing ...trend. Therefore, in Italy a voluntary based monitoring plan to control the safety of bivalve shellfish was set up at provincial level. This study describes the occurrence and distribution of Norovirus in different areas of Northern Italy seas.
Methods
Between the years 2018-2020 622 samples (n = 173 oysters, n = 139 mussels, n = 300 clams, n = 10 other bivalve shellfish) were tested by OneStep RT Real Time PCR for Norovirus GI and GII and quantified according to the ISO 15216:2017. Positive samples were further analyzed to determine genotype by sequencing of the ORF1/ORF2 junction of the Norovirus genome.
Results
A total of 111 (18%) samples were positive for Norovirus (mussels 22%; oysters 18%; clams 16%, other molluscs 20%), positive samples were found mainly in the winter season. The mean contamination was 103 ge/µL and ranged 100-105 ge/µL. Thirty-two samples were typeable (GI n = 10; GII n = 22) with GI samples belonging to four genotypes and GII samples belonging to five genotypes. GII.4, particularly Sydney 2012 subtype (found in three oysters and three clams samples), was the most prevalent, followed by GII.3. Often more than one genotype was found in samples collected simultaneously in the same sampling site. The virus was found with relatively high occurrence both in samples collected close to the coast (38%) and in those harvested from farms located 3-6 nautical miles offshore (73%).
Conclusions
The overall prevalence of Norovirus in edible shellfish, particular those to be eaten raw, is moderately high (18%). No difference in contamination was highlighted among the different species or different sampling sites. One of the most prevalent variants found (i.e. GII.4 Sydney 2012) is a leading cause of infections worldwide.
Key messages
Given the moderately high proportion of positive samples (18%), oysters (which are often eaten raw), regardless of the origin, represent the main risk of infection. The presence of genotypes frequently involved in human infections strengthens the need for ongoing monitoring, which should be extended to all provinces involved in shellfish farming.
Abstract
Background
Listeria monocytogenes is a foodborne pathogen with low incidence but severe manifestations in at risk categories (up to 30% fatality rate in YOPI). L. monocytogenes can form ...biofilm and persist in food processing environments for decades. In the Lombardy Region up to 50% of listeriosis cases have been attributed to dairy products. This study aimed at investigating a L. monocytogenes clone widely present in one of the most important Italian cheese production chain.
Methods
Through a retrospective analysis of the Lombardy Region PFGE database a cluster comprising isolates from eight PDO Gorgonzola and Taleggio dairies (2013-2019) was identified. A representative subset of 33 isolates was typed with MLVA and MLST. All isolates were further typed with WGS and compared to all Lombardy clinical isolates (n = 9) that shared the same Sequence Type (ST). Genomic relationship among isolates were investigated with cgMLST and SNP analysis.
Results
All isolates had the same MVLA/MLST profile (ST325). cgMLST and SNP analysis divided the isolates in two clusters that however shared a very high similarity (99.4%). Interestingly, isolates collected from same production plants clustered separately. Conversely, isolates collected in different years and plants clustered together. By querying the L. monocytogenes MLVA database it was possible to identify isolates of the same production chain with identical profile back to the year 2005. ST325 clinical isolates represented 2% of all typed clinical isolates and have an incidence of 0.007 cases/100000 inhabitants. Due to the high genomic similarity, it was not possible to link any clinical isolate to a putative source.
Conclusions
Our data suggest a persistent contamination by a L. monocytogenes ST325 clone traced back to the year 2005 present in the dairy production chain of Lombardy. Given the high similarity among the isolates further analyses with a larger dataset and are needed to elucidate the epidemiology of this clone.
Key messages
A highly clonal contamination by L. monocytogenes is widespread in the Lombardy Region dairy production chain. The low incidence of ST325 among the population suggests a low pathogenicity of the strain, however the occurrence of an ongoing long-term outbreak cannot be excluded.
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