Monitoring and Genotyping of Norovirus in Bivalve Molluscan Shellfish from Northern Italian Seas (2018-2020)

Norovirus (NoV) is an enteric virus with foodborne transmission. Bivalve shellfish are a main source of infections and outbreaks. In Italy a voluntary based monitoring plan to check the safety of bivalve shellfish was set up at provincial level. This study describes the occurrence and distribution of NoV in the Northern Adriatic Sea and in the Ligurian Sea. From October 2018 to September 2020, 807 bivalve shellfish samples (n = 205 oysters, n = 182 mussels, n = 348 clams, n = 72 other bivalve shellfish) were tested by One-Step Retrotranscription Real-time polymerase chain reaction for NoV GI and GII and quantified according to the ISO 15216-2:2013 and ISO 15216-1:2017. Positive samples were further analyzed to determine genotype by sequencing of the ORF1/ORF2 junction of the viral genome. A total of 126 samples were positive for NoV, mussels, and oysters had the highest probability of being positive and positive samples were found mainly in the colder season. Of these samples, 46% were NoV GII, 13% NoV GI, and 40% carried both genogroups. Thirty-seven samples were typeable (GI n = 12 and GII n = 25) with GI samples belonging to four genotypes and GII samples belonging to five genotypes. GII.3 genotype was the most prevalent, followed by GII.4, particularly Sydney 2012 subtype, a leading cause of infections worldwide, was found in three oysters' and three clams' samples. The phylogenetic analysis revealed a high heterogeneity among the species that are scattered in several clusters. Considering the low infectious dose the overall presence of NoV in edible shellfish, particular those to be eaten raw or undercooked, is moderately high. The presence of genotypes frequently involved in human infections strengthens the need for ongoing monitoring, which should be extended at national level.

Gluten quantification in gluten-free food for celiac people in Lombardy and Emilia Romagna - Italy

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.

Is SARS-CoV-2 a Concern for Food Safety? A Very Low Prevalence from a Food Survey during the COVID-19 Pandemic in Northern Italy

In 2019, SARS-CoV-2 was identified as the cause of an easily transmissible disease that was declared as a world pandemic. Foodborne transmission was never reported. However, early studies suggested that food could be involved in SARS-CoV-2 entry in the human gastrointestinal tract leading to possible infection, and highlighting the importance of further studies to inspect possible issues linked to food consumption. In this perspective, this work aimed at monitoring SARS-CoV-2 presence in some food and mains water samples in Northern Italy during the COVID-19 pandemic (2020–2022). A total of 1806 foods, 112 mains water samples, and 580 swabs on meat and dairy product surfaces were analyzed for SARS-CoV-2 RNA detection by Real-time PCR. All the analyzed samples were negative to viral RNA detection with the exception of one vegetable sample. Even if data on foodborne coronavirus transmission suggested a limited importance of this pathway, the impact of the current pandemic in Northern Italy deserved a rigorous investigation to rule out such possibility. Indeed, gaining insight on all SARS-CoV-2 possible transmission pathways, including the foodborne route, seemed of interest to maintain consumers’ confidence and trust in food safety, and for the effective management of the current, and future, possible pandemics.

Detection of Hepatitis A Virus and Norovirus in Different Food Categories: A 6-Year Survey in Italy

To observe the prevalence of contamination by hepatitis A virus (HAV) and norovirus (NoV) in different food types, 9242 samples were analyzed over a 6-year period (January 2014-December 2019). Samples were from routine official activities by Competent Authorities (CAs) and Food Business Operators, according to Hazard Analysis and Critical Control Points plans. Analyses were performed in accordance with European and Italian regulations. Food types were obtained from different production areas of Italy, and ranged from mollusks, ready-to-eat (RTE) and packaged vegetables, frozen berries, tap water, fruit and RTE fruit salads, and processed and preserved foods. No risk management plans were set by the authors' laboratory, because they were still adopted by conferring customers. Analyses were conducted according to ISO/TS 15216-2:2013 (ISO in Part 2: Method for Qualitative Detection. International Organization for Standardization, Geneva, 2013). The data showed that 2.25% (95% CI: 2.0-2.6) of samples were contaminated by at least one virus type, and that the most detected pathogen was NoV GII (89.50% of all positives). Mollusks (filter-feeding animals) were the most contaminated category (92.31% of all positives) not only by NoV or HAV individually, but also by multiple HAV/NoV contaminations consisting of 22.59% of all positives. For NoV, there was a significant correlation between shellfish positivity and season, with the autumn-winter period being the most associated with risk. Conversely, berries, drinking water and RTE vegetables, previously linked to several outbreaks, showed a low rate of contamination. These results from data collection have implications for the improvement of sampling plans for HAV and NoV by Italian CAs, and by food-producing and distribution operators. Moreover, these findings obtained by a standardized qualitative method contribute the collection of data aimed at establishing new microbiological criteria not yet foreseen (but advocated) by current European rules.

Torque Teno Sus Virus (TTSuV) Prevalence in Wild Fauna of Northern Italy

Torque teno sus virus (TTSuV) is a non-enveloped circular ssDNA virus which frequently infects swine and has been associated with hepatic, respiratory, and autoimmune disorders. TTSuV’s pathogenic role is still uncertain, and clear data in the literature on virus reservoirs are lacking. The aims of this study were to investigate the presence of potentially zoonotic TTSuV in wild animals in Northern Italy and to evaluate their role as reservoirs. Liver samples were collected between 2016 and 2020 during four hunting seasons from wild boars (Sus scrofa), red deer (Cervus elaphus), roe deer (Capreolus capreolus), and chamois (Rupicapra rupicapra). Samples originated from areas in Northern Italy characterized by different traits, i.e., mountains and flatland with, respectively low and high farm density and anthropization. Viral identification was carried out by end-point PCR with specific primers for TTSuV1a and TTSuVk2a species. TTSuV prevalence in wild boars was higher in the mountains than in the flatland (prevalence of 6.2% and 2.3%, respectively). In wild ruminants only TTSuVk2a was detected (with a prevalence of 9.4%). Our findings shed light on the occurrence and distribution of TTSuV in some wild animal species, investigating their possible role as reservoirs.

Monitoring of SARS-CoV 2 on primary production and manually processed foods in Northern Italy

Background

SARS CoV2 pandemic has generated interest in research of virus spread sources, apart from human contagion. In particular different studies are performed to understand surfaces involvement; during the epidemic event, different types of studies on surfaces have been performed. However, there is little information regarding the presence of the virus in food; wastewater contamination and poor hygiene practices could be the sources of viral contamination in handled food products. The aim of this work was to analyze different types of food for Sars CoV 2 presence.

Methods

390 samples of molluscs, 353 vegetables, 10 meat, 72 water, 169 berries, 16 seafood products and ready-to-eat dishes were analysed (2020-2021). Samples were selected from those provided for routine analysis during the pandemic period. The preparation was done based on ISO 15216-2 indications, followed by extraction with Nuclisense®Minimag® system; real-time PCR was applied to detect the Sars CoV2 virus Open Reading Frame 1ab, with two different master mixes.

Results

All samples tested were negative for ORF1ab detection. Many hypothesis can be made about negative Results: it could be possible that contamination levels in water, or on surfaces in contact with food, are too low to generate a detection signal; again, handling practices may be sufficient to avoid the transmission of the virus to food. Otherwise, the selected genetic target and the Real-time PCR performed, could have been not so efficient in detecting virus as expected.

Conclusions

In this preliminary work, food does not seem to be a substrate for Sars CoV2 contamination; other food categories or transformation/production processes could be investigated to confirm the obtained results. Also, different targets and amplification systems would have to be evaluated to verify the rule of foodstuffs as Sars CoV2 vehicles.

Key messages

Primary production and manual processed food don't seem to be at risk for SARS CoV2 contamination. Food has not been identified as a source of Sars CoV2 spreading.

One-Day Molecular Detection of Salmonella and Campylobacter in Chicken Meat: A Pilot Study

Salmonella and Campylobacter ssp. are bacterial pathogens responsible for most foodborne infections in EU countries. Poultry serves as a reservoir for these pathogens, and its important role in the meat industry makes it essential to develop a rapid detection assay able to provide results in one day. Indeed, the rapid identification of foodborne pathogens is an important instrument for the monitoring and prevention of epidemic outbreaks. To date, Salmonella and Campylobacter screening is mainly conducted through molecular methods (PCR or real-time PCR) performed after 18–24 h long enrichments. In this study, we evaluated short enrichments (0, 2, 4, and 6 h) combined with a colorimetric loop-mediated isothermal AMPlification (LAMP) or real-time PCR to detect Salmonella and Campylobacter in poultry meat contaminated at different concentration levels (10¹, 10³, and 10⁵ CFU/g). Our results show that real-time PCR allows the detection of Salmonella and Campylobacter, even after shorter enrichment times than prescribed by ISO references; particularly, it detected Salmonella down to 10¹ CFU/g since T0 and Campylobacter from 10³ CFU/g since T0. Detection with LAMP was comparable to real-time PCR without the requirement of a thermal cycler and with shorter execution times. These characteristics make colorimetric LAMP a valid alternative when one-day results are needed, improving the timely identification of positive meat batches, even in the absence of specialized instrumentation.

Utilization of Digital PCR in Quantity Verification of Plasmid Standards Used in Quantitative PCR

Quantitative PCR (qPCR) is a widely used method for nucleic acid quantification of various pathogenic microorganisms. For absolute quantification of microbial load by qPCR, it is essential to create a calibration curve from accurately quantified quantification standards, from which the number of pathogens in a sample is derived. Spectrophotometric measurement of absorbance is a routine method for estimating nucleic acid concentration, however, it may be affected by presence of other potentially contaminating nucleic acids or proteins and salts. Therefore, absorbance measurement is not reliable for estimating the concentration of stock solutions of quantification standards, based on which they are subsequently diluted. In this study, we utilized digital PCR (dPCR) for absolute quantification of qPCR plasmid standards and thus detecting possible discrepancies in the determination of the plasmid DNA number of standards derived from UV spectrophotometry. The concept of dPCR utilization for quantification of standards was applied on 45 qPCR assays using droplet-based and chip-based dPCR platforms. Using dPCR, we found that spectrophotometry overestimated the concentrations of standard stock solutions in the majority of cases. Furthermore, batch-to-batch variation in standard quantity was revealed, as well as quantitative changes in standards over time. Finally, it was demonstrated that droplet-based dPCR is a suitable tool for achieving defined quantity of quantification plasmid standards and ensuring the quantity over time, which is crucial for acquiring homogenous, reproducible and comparable quantitative data by qPCR.

Evaluation of Norovirus contamination in bivalve molluscs harvested from Northern Adriatic Sea, Italy

Background

Norovirus (NoV) is the leading cause of acute gastroenteritis in developed countries. Transmission is through direct contact, unsanitary food handling or ingestion of contaminated water or food. Shellfish bioaccumulate NoV and current post-harvest depuration is not effective for its removal.

Materials and

Methods

A monitoring programme for NoV in bivalve shellfish harvested from Northern Adriatic Sea was initiated in 2016. From January 2016 to March 2019, 418 samples including 257 Manila clams, 73 mussels, 46 striped clams, and 42 oysters, were examined. Mollusc samples were tested for NoV genogroups I (NoV GI) and II (NoV GII) contamination by RealTime RT-PCR according to ISO 15216-2.

Results

Ninety-three out of 418 tested samples (22.2%) were contaminated by at least one NoV genogroup, the simultaneous presence of the two genogroups was detected in 19/418 of the cases. Positive samples were distributed among the tested species as follow: 29/73 (39.7%) mussels, 51/257 (19.5%) Manila clams, 8/42 (19.0%) oysters, 5/46 (10.9%) striped clam. In 2016 (n = 135), 2017 (n = 122), 2018 (n = 132) and in the first trimester of 2019 (n = 12), prevalence of NoV was 6.7%, 24.6%, 31.8% and 41.4%, respectively. NoV GII was largely predominant being detected, alone or in association with GI, in 98.9% of the contaminated samples. On the other hand, GI prevalence increased from 1.5% (2016) to 12.1% in 2018, maybe reflecting a higher circulation of this genogroup in production environments.

The vast majority of positive samples (91.4%) were detected during the cold season (November to March).

Conclusions

Overall positive samples have increased over the years (from 6.7% in 2016 to 31.8% in 2018). NoV GII was the most frequently detected genogroup, but NoV GI prevalence significantly raised in 2018. The routine application of quantitative RT-PCR (ISO 15216-1) to determine the viral load in bivalve molluscs would expand knowledge on potential for foodborne transmission.

Key messages

Overall positive samples have increased over the years. The routine application of quantitative PCR to determine the viral load in bivalve molluscs would expand knowledge on potential for foodborne transmission.

Contamination of Poultry Meat with Salmonella infantis should be considered a Risk for Food Safety?

Issue/problem

EU Regulation regarding fresh poultry meat considers only S. enteritidis or S. typhimurium as Food Safety Criteria. On the contrary, the isolation of other Salmonella spp. in this food matrices is considered compliant. Several bibliographical sources indicate an increase in the isolation trend of S. infantis in the poultry industry and in derived products.

Description of the problem

Episodes of food poisoning caused by fresh chicken meat contaminated with S. infantis have been recently reported. According to CDC, last year in USA, an outbreak caused by a S. infantis strain, resistant to multiple antibiotics, ended with 129 sick people, 25 hospitalizations and a death. National Salmonellosis Control Plan for Poultry 2019-21 establishes in Italy the abatement conditions for poultry farms in case of positive isolation of S. enteritidis, S. typhimurium and S. infantis.

Results

In 2018, the National Health System disposed the analysis of batches of fresh chicken meat from Poland, sampled in a cold storage facility in Northern Italy. Food Control Dept. of IZSLER analysed 156 samples for a total of 780 sampling units (s.u.), for Salmonella spp.: 72 samples were positive (46,15%;corresponding to 222 s.u. - 28,46%). 42 strains were serotyped as S. enteritidis, 149 as S. infantis, 26 as S. newport, 4 as S. kentucky and 1 as S. mbandaka. According to EU Regulation, batches positive for S. enteritidis were indicated as not compliant, but batches positive to other Salmonella were considered regular.

Lessons

EU legislation allows the circulation of chicken meat contaminated with S. infantis. Chicken meat should be consumed after appropriate well cooking eliminating this hazard, but it does not protect the consumer from the risk of cross-contamination of tools and surfaces at the household level. It’s therefore fundamental the application of correct processing practices in order to prevent the spreading of Salmonella in home kitchens and limit dangerous episodes of infection.

Key messages

S. infantis trend of isolation in the poultry industry is increasing. application of GMPs in home cooking is fundamental to limit food outbreaks of infection.

Integrated veterinary-medical activity on characterization of shigatoxin producing Escherichia coli

Background

Shiga toxin-producing Escherichia coli (STEC) are an important public health concern as they cause severe conditions (bloody diarrhea and hemolytic uremic syndrome - HUS) and have epidemic potential. Cattle are the main reservoir for the highly virulent STEC O157 strain, and other HUS-associated non-O157 strains. This study aimed to characterize strains from animals and humans and to compare their molecular profiles. Animal isolates were tested for the presence of virulence factors correlated to their pathogenic potential.

Methods

74 STEC human isolates from 43 clinical cases (sporadic or epidemic) and 270 animal isolates from feces from 62 cattle farms were collected. Epidemiological investigation to collect environmental and suspected food samples was carried out for 22 cases. All isolates were typed with PFGE and their serotype was defined by Real-Time PCR. Animal isolates were also tested for the presence of subAB, saa, tia, cfk, adfO, hlyA, efaI1-lifA5’3’, and toxB virulence genes.

Results

O157 was detected in 44% of human cases, other relevant serogroups O26, O111, O103, O145 in 21, 9, 5 and 5% of cases, respectively. The source of infection was identified in one case (cheese contaminated by a O157 strain). Among animal isolates 2, 0.7, 0.7 and 0.3% were identified as O157, O11, O113, and O145, respectively. PFGE highlighted a high heterogeneicity among animal strains, however no pulsotype common to cattle and clinical isolates was found. adfO, cfk, efaI1-lifA5’3’ and toxB were found significantly correlated to eae (intimin).

Conclusions

Human and cattle strains were not correlated, however STEC diversity in cattle was very high and included some strains potentially pathogenic to humans. For this reason, upholding an integrated surveillance is very important.

Key messages

Serotypes relevant to human health were found in cattle in a small but not negligible frequence. No direct correlation was found between animal and clinical isolates.

Comparison among the Quantification of Bacterial Pathogens by qPCR, dPCR, and Cultural Methods

The demand for rapid methods for the quantification of pathogens is increasing. Among these methods, those based on nucleic acids amplification (quantitative PCRs) are the most widespread worldwide. Together with the qPCR, a new approach named digital PCR (dPCR), has rapidly gained importance. The aim of our study was to compare the results obtained using two different dPCR systems and one qPCR in the quantification of three different bacterial pathogens: Listeria monocytogenes, Francisella tularensis, and Mycobacterium avium subsp. paratuberculosis. For this purpose, three pre-existing qPCRs were used, while the same primers and probes, as well as PCR conditions, were transferred to two different dPCR systems: the QX200 (Bio-Rad) and the Quant Studio 3D (Applied Biosystems). The limits of detection and limits of quantification for all pathogens, and all PCR approaches applied, were determined using genomic pure DNAs. The quantification of unknown decimal suspensions of the three bacteria obtained by the three different PCR approaches was compared through the Linear Regression and Bland and Altman analyses. Our results suggest that, both dPCRs are able to quantify the same amount of bacteria, while the comparison among dPCRs and qPCRs, showed both over and under-estimation of the bacteria present in the unknown suspensions. Our results showed qPCR over-estimated the amount of M. avium subsp. paratuberculosis and F. tularensis cells. On the contrary, qPCR, compared to QX200 dPCR, under-estimated the amount of L. monocytogenes cells. However, the maximum difference among PCRs approaches was <0.5 Log₁₀, while cultural methods underestimated the number of bacteria by one to two Log₁₀ for Francisella tularensis and Mycobacterium avium subsp. paratuberculosis. On the other hand, cultural and PCRs methods quantified the same amount of bacteria for L. monocytogenes, suggesting for this last pathogen, PCRs approaches can be considered as a valid alternative to the cultural ones.

The importance of an early alert from the Microbiology Laboratory and multidisciplinary collaboration during a suspected salmonellosis outbreak

<em>Background and aims.</em> Salmonellosis is one of the most common and widely distributed food-borne diseases. The increasing complexity and globalization of the food industry are causing an increase of some of these large-scale food-borne illnesses, thus there is a need for improvements in public health signal detection and communication streams between laboratories and regulatory agencies. The aim of this study is to show how the early reporting of salmonellosis cases directly from the Laboratory of Microbiology to the Local Health Service Infectious Diseases Office along with the prompt response of the ASL, and the rapid involvement of the Local Veterinary Prevention Department resulted in an improved individuation and investigation of a suspected food-borne outbreak with anomalous manifestation. <br /><em>Materials and methods.</em> From August to November 2014 the early warning from the Laboratory of Microbiology regarding <em>Salmonella</em> spp. isolates with the identical serogroup and antibiotic resistance phenotype, allowed for prompt identification of a food-borne infection. <br /><em>Results and conclusions.</em> The genotyping analysis suggested that over the period considered there was more than a single monophasic <em>Salmonella</em> <em>typhimurium</em> isolate: one responsible for the sporadic cases that occurred in September and October, and another in November.

Seasonal Variability of Thermophilic Campylobacter Spp. in Raw Milk Sold by Automatic Vending Machines in Lombardy Region

In temperate climates, a seasonal trend was observed in the incidence of human campylobacteriosis cases, with peaks reported in spring and autumn in some countries, or in summer in others; a similar trend was observed in Campylobacter spp. dairy cattle faecal shedding, suggesting that cattle may play a role in the seasonal peak of human infection. The objectives of this study were to assess if a seasonal trend in thermophilic Campylobacter spp. contamination of raw milk exists and to evaluate a possible relation between this and the increase of human campylobacteriosis incidence in summer months. The results showed a mean prevalence of 1.6% of milk samples positive for thermophilic Campylobacter spp. with a wide range (0.0-3.1%) in different months during the three years considered. The statistical analysis showed a significant difference (P<0.01) of the prevalence of positive samples for thermophilic Campylobacter spp. between warmer and cooler months (2.3 vs 0.6%). The evidence of a seasonal trend in thermophilic Campylobacter spp. contamination of raw milk sold for direct consumption, with an increase of the prevalence in warmer months, may represent one of the possible links between seasonal trend in cattle faecal shedding and seasonal trend in human campylobacteriosis.

Genomic characteristics of Staphylococcus aureus strains associated with high within-herd prevalence of intramammary infections in dairy cows

Staphylococcus aureus is one of the most important causes of mastitis in dairy cattle. Based on previous research, Staph. aureus genotypes with different pathogenic and contagious properties can cause intramammary infection (IMI) and coexist in the same herd. Our study aimed to compare Staph. aureus strains from herds that differed in IMI prevalence using different molecular approaches such as ribosomal spacer (RS)-PCR, multilocus sequence typing (MLST), spa typing, ribotyping, pulsed-field gel electrophoresis (PFGE), and multiplex PCR. For this purpose, 31 dairy herds with Staph. aureus IMI were selected, and 16 of these were chosen for a comparison study: the 8 high-prevalence (HP) herds had Staph. aureus IMI prevalence >28% and the 8 low-prevalence (LP) herds had an IMI prevalence <4%. A total of 650 isolates of Staph. aureus from mammary quarters of all positive cows were genotyped with RS-PCR, a technique based on amplification of a portion of the intergenic spacer 16S-23S rRNA, and a subset of 54 strains was also analyzed by multiplex PCR, ribotyping, PFGE, MLST, and spa typing. The RS-PCR analysis revealed 12 different profiles. Staphylococcus aureus strains isolated from 5 out of 8 HP herds showed a profile identical to the genotype B (GTB), described in previous studies as being strongly associated with high within-herd prevalence of Staph. aureus mastitis and the presence of the genes coding for enterotoxins sea, sed, and sej, a long x-region of spa gene, and 3 lukE fragments. Moreover, all strains isolated in the HP herds possessed genes coding for staphylococcal enterotoxins. In LP herds, a limited number of strains of 6 genotypes, different from those isolated in HP herds, were identified and GTB was not found. Within these genotypes, 4 strains were positive for the mecA gene. Preliminary results and comparison with other genotyping methods confirmed that genotyping by RS-PCR is an accurate, rapid, and inexpensive tool for future field studies on Staph. aureus mastitis strains and generates clinically relevant results.

Behaviour of Listeria Monocytogenes and Escherichia Coli O157:H7 During the Cheese Making of Traditional Raw-Milk Cheeses from Italian Alps

The behaviour of Listeria monocytogenes and Escherichia coli O157:H7 was studied during the manufacture and ripening of two traditional Italian Alps cheeses. Each cheese type was manufactured in a pilot plan from raw cow milk (without the addition of starter cultures) artificially inoculated with L. monocytogenes and E. coli O157:H7 to a final concentration of about 4 log CFU/mL. The pathogens were enumerated throughout the cheese making and ripening processes to study their behaviour. When the milk was inoculated with 4 Log CFU/mL, the pathogens counts increased in the first time during the manufacturing process and then remained constant, until the end of ripening, or decreased significantly. Results indicate that the environment and nature of food borne pathogens affected the concentration of the bacteria during the manufacturing and ripening process. Thus, the presence of low cells numbers of L. monocytogenes and E. coli O157:H7 in milk destined for the production of raw milk cheeses characterized by a cooking of the curd less than 48°C can constitute a hazard for the consumer.

Detection and Molecular Characterisation of Swine Hepatitis E Virus in Brescia Province, Italy

Hepatitis E virus (HEV) is an important public health concern in many developing countries and it occurs in sporadic forms in industrialized areas. With the discovery of swine HEV in pigs, which is genetically closely related to human HEV, hepatitis E is considered to be a zoonotic disease. To investigate the circulation of HEV within a distinct area of Lombardy region (Northern Italy), 17 pig farms were subjected to monitoring study by collection of fresh stool samples each represented by ground-pooled specimens. In particular, three distinct types of breeding farms were focused, represented by farrow to weaning, farrow to finish and fattening farms, respectively. Epidemiological data confirm that in Europe the seroprevalence in pigs, more than 9 month of age, ranges from 51.4 to 75%, while in 3-9 months fatteners is about 38%. In France and Italy, the positivity among farms is respectively 30 and 97.4% and the seroprevalence in Italy is 50.2%. Since HEV viremia was typically observed in the early period of life in swine, faeces were collected in boxes containing weaning pigs. For the study, 183 stool samples were collected and amplifications were performed with universal primers specific for the ORF2 region of genome. Twentyeight samples resulted positive to HEV RNA and genotyping demonstrated that they were closely related to HEV strains belonging to genotype 3 and circulating in Europe. Comparison with reference strains from GenBank excluded their similarity to genotype 1, 2 or 4 confirming that genotype 3 strains are circulating in Europe. Since it was demonstrated that swine act as a reservoir for HEV, and since many strains into HEV genotype 3 share a strong molecular similarity to human HEV, it was important to detect the presence of HEV in a restricted area with a very high density of pigs.

Synergistic effect of high hydrostatic pressure (HHP) and marination treatment on the inactivation of hepatitis a virus in mussels (Mytilus galloprovincialis)

Consumption of raw or insufficiently cooked mussels contaminated with hepatitis A virus (HAV) is a major cause of infection to humans. The origin of mussels commonly used for the preparation of marinated seafood salads is often unknown, since different producers worldwide undergo a precooking treatment at the original collection site with methods and parameters not always indicated. These treatments could be insufficient for the inactivation of HAV, which is characterized by a high temperature resistance. Both high hydrostatic pressure (HHP) and marinade treatments have been shown to affect HAV vitality. In this study, two treatments (HHP and marinating) were combined in order to assess a potential synergistic effect on the virus vitality. A kinetic test was conducted by subjecting the experimentally-contaminated mussels (HAV titre: 10(6)/ml TCID50) to marinating, and to different HHP treatment (4,000; 5,000; and 6,000 bar for 1, 5, and 9 min). Virus post-treatment vitality was assessed by its ability to grow on cell cultures and by quantitative real-time RT-PCR to evaluate virus resistance under such conditions. Marinating treatment alone (final pH 4.3, and NaCl 2 %) did not inactivate the virus. On the other hand, the use of HHP treatment alone on non-marinated HAV-contaminated mussels was effective only above 5,000 bar for 5 min. The results of the present study elucidate the synergistic effect of a combination between marination and HHP treatments on the inactivation of the virus.

Quantitative risk assessment of human salmonellosis and listeriosis related to the consumption of raw milk in Italy

Two quantitative risk assessment (RA) models were developed to describe the risk of salmonellosis and listeriosis linked to consumption of raw milk sold in vending machines in Italy. Exposure assessment considered the official microbiological records monitoring raw milk samples from vending machines performed by the regional veterinary authorities from 2008 to 2011, microbial growth during storage, destruction experiments, consumption frequency of raw milk, serving size, and consumption preference. Two separate RA models were developed: one for the consumption of boiled milk and the other for the consumption of raw milk. The RA models predicted no human listeriosis cases per year either in the best or worst storage conditions and with or without boiling raw milk, whereas the annual estimated cases of salmonellosis depend on the dose-response relationships used in the model, the milk storage conditions, and consumer behavior in relation to boiling raw milk or not. For example, the estimated salmonellosis cases ranged from no expected cases, assuming that the entire population boiled milk before consumption, to a maximum of 980,128 cases, assuming that the entire population drank raw milk without boiling, in the worst milk storage conditions, and with the lowest dose-response model. The findings of this study clearly show how consumer behavior could affect the probability and number of salmonellosis cases and in general, the risk of illness. Hence, the proposed RA models emphasize yet again that boiling milk before drinking is a simple yet effective tool to protect consumers against the risk of illness inherent in the consumption of raw milk. The models may also offer risk managers a useful tool to identify or implement appropriate measures to control the risk of acquiring foodborne pathogens. Quantification of the risks associated with raw milk consumption is necessary from a public health perspective.

Isolation and genomic sequence of hepatitis A virus from mixed frozen berries in Italy

Hepatitis A virus (HAV) was detected in two samples of mixed frozen berries linked to Italian hepatitis A outbreak in April and September 2013. Both viruses were fully sequenced by next-generation sequencing and the genomes clustered with HAV complete genomes of sub-genotype IA with nucleotide identities of 95-97%.

Study of Growth Potential of Listeria Monocytogenes in Low Fat Salami: An Innovative Italian Meat Product

In the last years, consequently to EC Regulation no. 1924/2006 on nutrition and health claims made on foods, some Italian food businnes operators (FBOs) leaders in the meat sector, invested in research to develop innovative products such as low fat salami, containing up to 30% less fat than the traditional one. For FBOs it is essential to demonstrate for each production process whether the substrate allows the growth of L. monocytogenes and whether L. monocytogenes could reach or exceed the limit of 100 cfu g-1 at the end of the shelf life, as stated by EC Regulation no. 2073/2005. In the present study, the growth potential of L. monocytogenes during the shelf life of low fat salami packed in modified atmosphere was evaluated. The results show that the product is unable to support the growth of pathogen, even if the storage temperature is between 8 and 12°C.

Growth Potential of Listeria Monocytogenes in Sliced Turkey Bresaola Packed in Modified Atmosphere

According to EC Regulation No 2073/2005, for food business operators that produce ready-to-eat (RTE) product, it is crucial to be able to demonstrate if the product supports the growth of Listeria monocytogenes. The objective of the study was therefore to evaluate the behaviour of L. monocytogenes in sliced RTE turkey bresaola (made by cured turkey breast 4.5% NaCl, 1% sodium lactate, sodium nitrite 150 ppm and flavouring) during the shelf life of the product, simulating a contamination during the slicing operation. Considering a shelf life of 90 days, as defined by manufacturer, the packages of sliced bresaola were stored at 5°C for 7 days and at 8°C for the remaining storage time (83 days). L. monocytogenes count decreased during storage test from 1.43/1.98 log cfu/g in the three batches tested to 1.03 log cfu/g in one batch and to undetectable levels in the other two batches. The results show that the investigated product is unable to support the growth of L. monocytogenes.

Behaviour of Escherichia Coli O157:H7 During the Manufacture and Ripening of an Italian Traditional Raw Goat Milk Cheese

Formagelle di capra is a raw goat cheese produced from whole chilled goat milk; traditional technology involving unpasteurised milk and indigenous lactic starter cultures is employed for its production in Italy. The purpose of this study was to assess the behaviour of Escherichia coli O157:H7 during the manufacturing and ripening of this raw goat milk cheese. Raw milk was experimentally inoculated with E. coli O157:H7 in a laboratory scale plant and the count was monitored during production and 30 days of ripening required for this cheese. Results showed that E. coli O157:H7 count increased to more than 1.5 Log cfu g-1 during cheese production and remained constant until the end of ripening. The evidence that E. coli O157:H7 is able to survive during the manufacturing and ripening process suggests that the 30-day ripening period alone is insufficient to eliminate levels of viable E. coli O157:H7 in Formaggelle di capra cheese and that the presence of low numbers of E. coli O157:H7 in milk destined for the production of raw goat milk cheeses could represent a potential source of infection for humans and a threat for consumers.

Two unlinked cases of foodborne botulism in Italy at the beginning of 2010

The study provides data on two cases of foodborne botulism caused by consumption of commercial vegetable products: artichoke preserve and cream of vegetable soup. By mouse bioassay, Clostridium botulinum toxin in both the suspected food samples was detected and identified as type B toxin. The detection of C. botulinum toxin in the artichoke preserve indicates an inadequate food production technology while the presence of C. botulinum toxin in the vegetable soup appeared to be related to wrong behavior on the part of the consumer and to faulty food preservation. The study confirms that an early identification and reporting of suspected botulism cases is vital in the prevention of accidental widespread outbreaks.

Evaluation of the protective effects of alpha-tocopherol and retinol against ochratoxin A cytotoxicity

Ochratoxin A (OTA), a mycotoxin frequently present in food and feedstuffs, produces a wide range of toxic effects, including cell death via lipid peroxidation. In one human and four animal cell lines we determined the half lethal concentration (LC50) of OTA, its effect on reactive oxygen species (ROS) production, and its ability to induce cytochrome p450 activity. We also examined the protective effect of alpha-tocopherol and all-trans-retinol in the most sensitive cell lines (i.e. bovine mammary epithelia, for which LC50 was 0.8 microg/ml (24 h), and Madin Darby canine kidney, for which LC50 was 4.3 microg/ml (48 h)). Pre-incubation for 3 h with either antioxidant significantly (P<0.05) ameliorated the OTA-induced reduction in cell viability and significantly decreased (P<0.05) ROS production. These findings indicate that oxidative stress is an important factor in OTA cytotoxicity. Supplementation with antioxidant molecules may counteract the short-term toxicity of this mycotoxin.

[Role of the Istituti Zooprofilattici Sperimentali in controlling the microbiological and toxicologic risks related to seafood]

The "Istituti Zooprofilattici" are an important network whose main function is the monitoring of animal health as well as food. As a result of the recent improvements in aquaculture technology interest in the safety of seafood is increasing. Therefore, the purpose of this study was to set up diagnostic methods for the detection of virus contamination, as well as the use of in vitro techniques able to identify the different toxins. The results have allowed the development of molecular biology assays which, together with the isolation in cell cultures, can detect contaminations/infections by the hepatitis A virus and the most common enteroviruses. Moreover, specific selected cell lines have led to the detection of different toxins. These laboratory methods will be used in order to control seafood safety.

[In vitro study of the nephrotoxic mechanism of mercuric chloride]

OBJECTIVES

Mercury (Hg), one of the most diffused and hazardous organ-specific environmental contaminants, exists in a wide variety of physical and chemical states, each of which with unique characteristics of target organ specificity. Exposure to Hg vapour and to organic mercurials specifically affects the CNS, while the kidney is the target organ for inorganic Hg compounds. Despite the increasing number of studies, the molecular bases of the nephrotoxic potential of Hg has not, up to now, been clarified, even if there is evidence suggesting that the ability of the metal to interact with proteins (thiol groups) or to generate oxygen radicals may play a major role. Within this context, the aim of the present study was to investigate, in vitro, the mechanism(s) of the early nephrotoxic potential of mercury chloride (HgCl2), one of the most diffused and biologically active mercury (Hg2+) compounds. For this purpose, two kidney-derived in vitro systems (the MDCK and the LLC-PK1 cell lines) were tested for their sensitivity to the salt, and MDCK was chosen as the most suitable in vitro model for our study. As possible biological markers of the organ-specific toxicity of the metal we analysed: i) critical biochemical parameters related to oxidative stress conditions (effect of Hg2+ on the anti-oxidant status of the cell), and ii) gap-junctional function (GJIC).

METHODS

Classical toxicity tests (MTT and NR) were used for assessing the sensitivity (IC50) of LLP-CK1 and MDCK cell lines to the mercuric salt. Complete solubilisation of the salt in the culture media was verified by inductively coupled plasma mass spectrometry (ICP-MS). The influence of the metal on cell growth rate and viability were evaluated by conventional proliferation assays. For the following mechanistic studies, cells were exposed for different time periods (4 to 72 hours) to non-cytotoxic (0.1-50 microM) HgCl2 concentrations. The biochemical analysis of the pro-oxidant properties of the mercuric compound was performed by the measurement of anti-oxidant cellular defences against H2O2 [catalase (Cat), glutathione peroxidase (Gpx), and total glutathione (GSH)]. The influence of the metal on the GJIC capacity of MDCK cells was assessed by the "microinjection/dye-coupling" assay.

RESULTS

Among the two kidney-derived in vitro systems, MDCK cell line was the most specifically sensitive to the toxic effect of HgCl2: it was, consequently, chosen as a "tubular cell model" for the following experimental steps. Tested for various time periods at increasing concentrations, the HgCl2 effect on MDCK cell proliferation and viability was found to be time- and dose-related. For concentrations < or = 50 microM, HgCl2 inhibits MDCK cell growth rate, being this effect significant (> 50% in respect to untreated controls) from the 24th from the beginning of the treatment, while, for concentrations > 50 microM, the metal causes cell death. Concerning the influence of HgCl2 on MDCK anti-oxidant defences, the most interesting results were obtained by analysing the influence of the mercury salt on the GSH cell content and Gpx activity. Both were, in fact, significantly affected by the presence of the mercury ion. HgCl2 also induced a rapid, dose- and time-related inhibitory effect on the GJIC capacity of the cells.

CONCLUSIONS

Even if further investigations are needed to better clarify the possible causal relationship between our findings, they indicate that: a) MDCK cells represent a suitable in vitro model for the study of Hg nephrotoxicity; b) GJIC function is, among those considered in our study, one of the most sensitive biological endpoints for investigating the mechanism(s) of Hg2+ specific toxicity.