N.C. Quaglia

Assessment of mercury and cadmium via seafood consumption in Italy: estimated dietary intake (EWI) and target hazard quotient (THQ)

Mercury (Hg) and cadmium (Cd) were quantified in fish, cephalopods and crustaceans from Italian supermarkets. Sample compliance with European dietary standards as well as human health risks according to provisional tolerable weekly intake (PTWI) and the methodology of target hazard quotient (THQ) were evaluated. Both element levels were under European legal limits, except for some fish having Hg and Cd contents exceeding or equal to critical values. Estimated weekly intakes (Hg: fish = 0.07–1.44 µg kg−1 bw week–1; cephalopods = 0.05–0.15 µg kg−1 bw week–1; crustaceans = 0.04–0.08 µg kg−1 bw week–1; and Cd: fish = 0.04–0.32 µg kg−1 bw week–1; cephalopods = 0.07–0.27 µg kg−1 bw week–1; crustaceans = 0.05–0.11 µg kg−1 bw week–1) as well as THQ < 1 were within safe limits. Although there seems to be no important risks associated with seafood consumption, Hg exposure was in some cases close to safety margins and thus levels of this metal should be under frequent surveillance.

Verocytotoxin-producing Escherichia coli O26 in raw water buffalo (Bubalus bubalis) milk products in Italy.

Escherichia coli 026 is known as a verocytotoxin-producing E. coli (VTEC) organism that causes severe foodborne diseases such as hemorrhagic colitis and hemolytic uremic syndrome. Although cattle are the most important reservoir of VTEC, only a few reports on the role of water buffalo (Bubalus bubalis) as a reservoir of VTEC and on the presence of these organisms in their milk are available. However, in Southern Italy, where water buffalo are intensively reared, an outbreak of hemolytic uremic syndrome due to E. coli 026 has recently been reported, in which the consumption of typical dairy products was considered to be a common risk factor. The aims of this work were to assess the prevalence of E. coli O26 in raw water buffalo milk, to characterize the virulence gene profiles of the isolates, and to evaluate their phenotypic antimicrobial resistance pattern. Of 160 analyzed samples, 1 (0.6%) tested positive for E. coli O26, and the isolate showed the stx1+/stx2+/eae-/hlyA+ genotypic profile. The strain showed resistance against glycopeptides, macrolides, and penicillins. The presence of VTEC organisms in raw water buffalo milk could be considered to be a potential threat to consumers; however, the strict adherence to the processes used in the preparation of the most common buffalo dairy products could strongly mitigate the foodborne risk. To our knowledge, this article reports the first isolation and characterization of E. coli O26 VTEC in raw water buffalo milk.

Typing of Escherichia coli O157 strains isolated from fresh sausage

Abstract E. coli O157 is a foodborne pathogen responsible for serious human illnesses, such as hemorrhagic colitic and hemolytic uremic syndrome. Ground beef products are among the foods that are more commonly contaminated, and the strains isolated have been frequently found to carry virulence factors of this pathotype. This paper reports the results of serotyping assays and of investigations performed to screen for virulence factors of 10 E. coli O157 strains isolated from fresh sausages purchased at retail meat outlets in various provinces of Apulia (southern Italy). The presence of verocytotoxins was assessed on VERO cells and ELISA tests. Multiplex PCR assays were performed for the eae, stx1, stx2 and hlyA genes. Six of the 10 strains examined presented the H7 antigen and all of them proved to be potentially pathogenic due to the presence of individual or multiple virulence factors.

Microbiological quality of Burrata cheese produced in Puglia region: southern Italy.

Burrata cheese is a popular typical Italian food product, produced in Puglia (an administrative region of southern Italy), and this study investigated the microbiological quality of 404 samples of this cheese. The samples were analyzed in order to quantify Escherichia coli and to detect the presence of Staphylococcus aureus, Salmonella spp., and Listeria monocytogenes. No sample exceeded the values of E. coli set by EC Regulation 1441/07 for some dairy products, while 15 (3.7%) samples tested coagulase-positive staphylococci positive, with values greater than 10(3) CFU/g. One strain of S. aureus was identified and characterized from each of these positive samples, and of these strains, 7 (46.6%) produced staphylococcal enterotoxin A, 5 (33.3%) produced staphylococcal enterotoxin C, 2 (13.3%) produced staphylococcal enterotoxin D, and 1 (6.6%) produced both staphylococcal enterotoxins A and D. All strains were mecA negative. The 15 S. aureus isolates were tested for their antimicrobial resistance patterns, and all analyzed strains showed antimicrobial resistance properties for at least one of the tested antibiotics. Testing for the other pathogens mentioned above gave negative results. The results of our study mean that the microbiological quality of Burrata cheese can be assumed to be good, although care must be taken with raw materials and good hygiene during processing in order to guarantee greater food safety.

Multiplex-touchdown PCR assay for the detection and genotyping of Helicobacter pylori from artificially contaminated sheep milk.

Helicobacter pylori (Hp) is an organism commonly present worldwide in the human population, sometimes causing serious illnesses such as duodenal and gastric ulcers, adenocarcinoma of the stomach, and low-grade B-cell mucosa-associated lymphoid tissue lymphoma of the stomach. This article describes a multiplex-touchdown PCR method for the identification and genotyping (vacA-s1/m1, sl/m2, and s2/m2-and cagA genes) of Hp directly from sheep milk artificially contaminated with Hp strains from human gastric biopsies and with Hp ATCC 43504. The strains from humans carried sl/m2 cagA+ and s2/m2 cagA allelic combinations, while the ATCC strains carried an sl/ml cagA+ allelic combination. The technique showed a sensitivity of 15 CFU/ml for species identification and of 1,500 CFU/ml for the detection of genes encoding for VacA and CagA. It has proven to be specific and rapid, and the authors suggest that it be used as a rapid screening method to ensure that sheep milk is uncontaminated with this organism.

Market survey of Vibrio spp. and other microrganisms in Italian shellfish.

A survey was conducted of Vibrio spp., Escherichia coli, fecal coliforms, and Salmonella in 644 molluscan shellfish samples marketed in the Apulia region of southern Italy. Vibrios were found in 278 samples (43%), and levels of E. coli and fecal coliforms were above the Italian legal limit in 27 and 34 samples (4 and 5%), respectively. Salmonella was not detected in any of the samples. Because the majority of the vibrio isolates were found in samples that were compliant with Italian regulations, there appears to be no relationship between the presence of microorganisms of fecal origin and the presence of vibrios potentially harmful to human health.

Development of a multiplex PCR for rapid detection of verocytotoxin-producing Escherichia coli O26 in raw milk and ground beef.

Verocytotoxin-producing Escherichia coli (VTEC) O26 is an emergent pathotype that has caused an increasing number of sporadic cases and outbreaks of gastroenteritis, hemorrhagic colitis, and hemolytic uremic syndrome in the United States and Europe. Many cases are associated with the consumption of milk and undercooked or fermented meats. The stx(2) strains of VTEC O26 seem to be more likely to cause human infections than isolates expressing only stx(1). The isolation and identification of VTEC O26 from foods is labor intensive and time-consuming. We developed a multiplex PCR (M-PCR) assay for the identification and characterization of E. coli O26 VTEC and its detection in raw milk and ground beef. The method is based on the amplification of the wzx, stx(1), and stx(2) genes for the simultaneous detection of the O26 antigen and verocytotoxin types 1 and 2. This M-PCR assay had a sensitivity of 10(8) CFU/ml when applied to a bacterial suspension and of 10(6) CFU/ml or g when applied to both inoculated milk and minced beef samples. This M-PCR assay also was highly specific, and results were consistently negative for negative controls (nonpathogenic E. coli strains, uninoculated milk and beef samples, and samples inoculated with the nontarget microorganisms). This method could be used for the rapid detection of E. coli O26 VTEC from foods and for the rapid identification and characterization of clinical and environmental isolates.

Helicobacter pylori: A foodborne pathogen?

Helicobacter pylori (H. pylori) is an organism that is widespread in the human population and is sometimes responsible for some of the most common chronic clinical disorders of the upper gastrointestinal tract in humans, such as chronic-active gastritis, duodenal and gastric ulcer disease, low-grade B-cell mucosa associated lymphoid tissue lymphoma of the stomach, and gastric adenocarcinoma, which is the third leading cause of cancer death worldwide. The routes of infection have not yet been firmly established, and different routes of transmission have been suggested, although the most commonly accepted hypothesis is that infection takes place through the faecal-oral route and that contaminated water and foods might play an important role in transmission of the microorganism to humans. Furthermore, several authors have considered H. pylori to be a foodborne pathogen because of some of its microbiological and epidemiological characteristics. H. pylori has been detected in drinking water, seawater, vegetables and foods of animal origin. H. pylori survives in complex foodstuffs such as milk, vegetables and ready-to-eat foods. This review article presents an overview of the present knowledge on the microbiological aspects in terms of phenotypic characteristics and growth requirements of H. pylori, focusing on the potential role that foodstuffs and water may play in the transmission of the pathogen to humans and the methods successfully used for the detection of this microorganism in foodstuffs and water.

PCBs and PCDD/Fs in Bluefin Tuna: Occurrence and Dietary Intake

Polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-furans (PCDD/Fs) were measured in Mediterranean bluefin tuna (Thunnus thynnus) to verify the compliance with the EU regulations for food commercialization. The estimated intakes were also evaluated. The analyses were performed by gas chromatography-ion trap tandem mass spectrometry (GC-MS-MS). The PCBs were dominant (1132.0 ng g−1 l.w.), followed by PCDFs (23.2 pg g−1 l.w.) and PCDDs (8.5 pg g−1 l.w.). The pollutant levels (dl-PCBs: 0.7 pg TEQ/g w.w.; PCDD/Fs: 1.9 pg TEQ/g w.w.) and their sum expressed as TEQ values (2.6 pg TEQ/g w.w.) remained below the limits for human consumption proposed by the European Union. On the contrary, the sum of the six indicator non-dioxin-like PCBs (84.2 ng g−1 w.w.) was slightly above the maximum level fixed by the in-force legislation. The estimated dietary intakes for PCDD/Fs plus dl-PCBs were below the toxicological reference values (TRVs) set by various international bodies, while non-cancer and cancer risk assessment revealed a safety concern. Additionally, the estimated intake of ndl-PCBs exceeded the maximum levels set by different European countries. These findings suggest caution in tuna consumption together with an active and frequent surveillance of the chemical quality of its flesh.