Research Publications (Food Safety)

Global regulator of virulence A (GrvA) is a ToxR-family transcriptional regulator that activates locus of enterocyte effacement (LEE)-dependent adherence in enterohemorrhagic E. coli (EHEC). LEE activation by GrvA requires the Rcs phosphorelay response regulator RcsB and is sensitive to physiologically-relevant concentrations of bicarbonate, a known stimulant of virulence systems in intestinal pathogens.

Cyclic diadenylate monophosphate (c-di-AMP) is a second messenger utilized by diverse bacteria. In many species, including the Gram-positive human pathogen Listeria monocytogenes, c-di-AMP is essential for growth. Here we show that the single diadenylate cyclase of L. monocytogenes, CdaA, is an integral membrane protein that interacts with its potential regulatory protein, CdaR, via the transmembrane protein domain.

Summary

Avian influenza A(H9N2) is an agricultural and public health threat. We characterized an H9N2 virus from a pet market in Bangladesh and demonstrated replication in samples from pet birds, swine tissues, human airway and ocular cells, and ferrets. Results implicated pet birds in the potential dissemination and zoonotic transmission of this virus.

Hepatitis E virus (HEV) infection is a common acute hepatitis transmitted by the fecal-oral route. In developed countries, the virus has a zoonotic potential, and domestic pigs and wild boars are considered main reservoirs. To assess the prevalence of HEV-positive animals in the Calabria region (southern Italy) on a serological and molecular level, a total of 216 autochthonous healthy pigs (Apulo-Calabrese breed) were sampled. Both sera and feces were collected.

The aim of this study was to detect the prevalence of Salmonella spp., Listeria monocytogenes, and Yersinia enterocolitica in freshwater fish in Latvia. In total, 235 samples, including freshly caught fish from fives lakes (n = 129) and fish from retail markets (n = 106), were collected from April 2014 to December 2014 in Latvia. Samples were tested according to International Organization for Standardization methods. No Salmonella spp.

The aim of this study was to investigate the prevalence of Vibrio spp. in shrimp at retail and in shrimp farms in Ecuador and to determine the antimicrobial agent resistance patterns of farm isolates. The presence of genes linked to early mortality syndrome (EMS) or acute hepatopancreatic necrosis disease (AHPND) also was evaluated. Vibrio spp. were isolated from retail shrimps in Cuenca, Ecuador, and farm shrimps originating from provinces El Oro and Guayas, Ecuador.

Shiga toxin (Stx)–producing Escherichia coli (STEC) strains are food- and waterborne pathogens that are often transmitted via beef products or fresh produce. STEC strains cause both sporadic infections and outbreaks, which may result in hemorrhagic colitis and hemolytic uremic syndrome. STEC strains may elaborate Stx1, Stx2, and/or subtypes of those toxins.

Previous research demonstrated significant variation in the prevalence of Salmonella in peripheral lymph nodes (LNs) of feedlot cattle and cull cows, with greater prevalence in feedlot cattle. Therefore, we performed experiments to investigate whether these differences in Salmonella prevalence in subiliac LNs are due to, or influenced by, breed, which in many respects is a proxy for the production system in which the animal is derived.

This study was intended to characterize the perceived risks of urban agriculture by residents of four low-income neighborhoods in which the potential exists for further urban agriculture development and to provide data to support whether any chemical hazards and foodborne pathogens as potential food safety hazards were present. Sixty-seven residents participated in focus groups related to environmental health, food security, and urban gardening.

To evaluate the persistence of infectious virus after heating, mussels contaminated with a rotavirus strain were prepared following the French recipe moules marinières (mariner's mussels). Rotavirus was then quantified by real-time quantitative PCR (RT-qPCR) and a cell culture infectivity assay. Results showed the persistence of infectious virus after 3 min of cooking.

Osmotolerant yeasts are primarily responsible for spoilage of sugar-rich foods. In this work, an electronic nose (e-nose) was used to diagnose contamination caused by two osmotolerant yeast strains (Zygosaccharomyces rouxii and Candida tropicalis) in a high-sugar medium using test panel evaluation as the reference method.

Because of the major international-level events that have recently been held in Brazil, concerns about the sensory and hygienic-sanitary conditions of food have increased. The objective of this study was to evaluate the implementation of good handling practices in food and beverage areas of hotels, with and without outsourced professional intervention.

Almost one in seven American households were food insecure in 2012, experiencing difficulty in providing enough food for all family members due to a lack of resources. Food pantries assist a food-insecure population through emergency food provision, but there is a paucity of information on the food safety–related operating procedures used in the pantries.

Effective hand hygiene is essential to prevent the spread of pathogens on produce farms and reduce foodborne illness. The U.S. Food and Drug Administration Food Safety Modernization Act Proposed Rule for Produce Safety recommends the use of soap and running water for hand hygiene of produce handlers. The use of alcohol-based hand sanitizer (ABHS) may be an effective alternative hygiene intervention where access to water is limited.

The aim of this research was to evaluate the effect of thermal treatments (isothermal or nonisothermal) combined with nisin, a natural antimicrobial, on the survival and recovery of Clostridium sporogenes spores. The addition of nisin to the heating medium at concentrations up to 0.1 mg liter−1 did not reduce the heat resistance of C. sporogenes. Without a thermal treatment, nisin added at concentrations up to 0.1 mg liter−1 did not reduce the viable counts of C.

Shelf life of fish packaged under modified atmosphere (MA) is extended, but within the United States, commercial application of MA with impermeable packaging films is restricted due to concerns that botulinum toxin production would precede spoilage when contaminated fish are held at abusive storage temperatures.

A total of 156 Staphylococcus aureus isolates were obtained from 330 imported fresh fish samples from three countries. Selective media were used for the isolation of S. aureus, and the isolates were confirmed by PCR. The isolates were tested for mecA gene, antibiotic resistance, and enterotoxin genes (sea, seb, sec, sed, see, seg, seh, and sei). Most isolates carried sea, seg, and sei genes, and seg-sei was the most frequent enterotoxin profile. About 88.5% of the S.

A longitudinal study was conducted to determine the prevalence of Listeria spp. in a commercial fresh mushroom slicing and packaging environment. Samples were collected at three different sampling periods within a 13-month time interval. Of the 255 environmental samples collected, 18.8% tested positive for L. monocytogenes, 4.3% for L. innocua, and 2.0% for L. grayi. L. monocytogenes was most often found on wet floors within the washing and slicing and packaging areas. Each of the 171 L.

This study was conducted to evaluate the microbial quality of lamb and goat meat sold through local (Virginia) and Internet (U.S.) retail markets. A total of 134 frozen meat products consisting of locally purchased lamb ground (LLG) and lamb chops and Internet-procured lamb ground, goat ground, lamb chops (ILC), goat chops (IGC), lamb stew, and goat stew were tested.

Seafood is often associated with foodborne illnesses, and Vibrio parahaemolyticus is the most common pathogen implicated in outbreaks in Taiwan. In this study, the microbiological quality of 300 raw or mixed ready-to-eat (RTE) and other cooking-needed seafood samples was examined. The total aerobic and coliform counts of the RTE samples were significantly higher than those of other cooking-needed samples.

Studies were conducted to evaluate the efficacy of a commercial blend of sulfuric acid and sodium sulfate (SSS) in reducing Salmonella on inoculated whole chilled chicken wings and to compare its efficacy to peroxyacetic acid (PAA) and cetylpyridinium chloride (CPC).

The purpose of this study was to evaluate (i) the behavior of several strains of non-O157 Shiga toxin–producing Escherichia coli (STEC) serogroups (O26, O103, O111, and O145) exposed to different stress conditions and (ii) the growth dynamics of stressed and nonstressed non-O157 STEC cells in five enrichment media. STEC strains were exposed to acid, cold, and freeze stresses. Lethal and sublethal injuries were determined by plating in parallel on selective and nonselective agar media.

The survival of Salmonella on fresh ginger root (Zingiber officinale) during drying was examined using both a laboratory oven at 51 and 60°C with two different fan settings and a small commercially available food dehydrator. The survival of Salmonella in ground ginger stored at 25 and 37°C at 33% (low) and 97% (high) relative humidity (RH) was also examined. To inoculate ginger, a four-serovar cocktail of Salmonella was collected by harvesting agar lawn cells.

The objective of this study was to determine Salmonella levels (presence and numbers) in turkey drumstick bone, spleen, and neck skin samples in relation to Salmonella contamination levels in ground turkey at the flock level. Over a 10-month period, a total of 300 samples of each turkey part (i.e., neck skin, spleen, and drumstick) from 20 flocks were collected at a commercial turkey processing plant after the evisceration step.