Cause Of Foodborne Illness Research Articles

High-Resolution Comparative Genomics of Salmonella Kentucky Aids Source Tracing and Detection of ST198 and ST152 Lineage-Specific Mutations

Non-typhoidal Salmonella (NTS) is a major cause of foodborne illness globally. Salmonella Kentucky is a polyphyletic NTS serovar comprised of two predominant multilocus sequence types (STs): ST152 and ST198. Epidemiological studies have revealed that ST152 is most prevalent in US poultry whereas ST198 is more prevalent in international poultry. Interestingly, ST152 is sporadically associated with human illness, whereas ST198 is more commonly associated with human disease. The goal of this study was to develop a better understanding of the epidemiology of ST198 and ST152 in WA State. We compared the antimicrobial resistance phenotypes and genetic relationship, using pulsed-field gel electrophoresis, of 26 clinical strains of S. Kentucky isolated in Washington State between 2004 and 2014, and 140 poultry-associated strains of S. Kentucky mostly recovered from the northwestern USA between 2004 and 2014. We also sequenced whole genomes of representative human clinical and poultry isolates from the northwestern USA. Genome sequences of these isolates were compared with a global database of S. Kentucky genomes representing 400 ST198 and 50 ST152 strains. The results of the phenotypic, genotypic, and case report data on food consumption and travel show that human infections caused by fluoroquinolone-resistant (FluR) S. Kentucky ST198 in WA State originated from outside of North America. In contrast, fluoroquinolone-susceptible (FluS) S. Kentucky ST198 and S. Kentucky ST152 infection have a likely domestic origin, with domestic cattle and poultry being the potential sources. We also identified lineage-specific non-synonymous single nucleotide polymorphisms (SNPs) that distinguish ST198 and ST152. These SNPs may provide good targets for further investigations on lineage-specific traits such as variation in virulence, metabolic adaptation to different environments, and potential for the development of intervention strategies to improve the safety of food.

Global Genomic Characterization of Salmonella enterica Serovar Telelkebir.

Non-typhoidal Salmonella (NTS) is a common cause for self-limiting gastroenteritis, representing a public health concern globally. NTS is one of the leading causes of foodborne illnesses in China; however, the invasive infection caused by NTS is largely underappreciated. Here, we reported an NTS invasive infection caused by an infrequently reported serovar Telelkebir (13,23:d:e,n,z15) strain FJ001 in China, which carries antimicrobial-resistant genes [fosA7 and aac(6′)-Iaa] and typhoid-toxin genes (cdtB, pltA, and pltB). By conducting the whole genomic sequencing, we also investigated the relatedness of this strain with an additional 120 global contextual Salmonella enterica serovar Telelkebir (S. Telelkebir) isolates, and assessed the antimicrobial-resistant determinants and key virulence factors using the available genomic dataset. Notably, all 121 (100%) of the S. Telelkebir strains possessed the typhoid toxin genes cdtB, pltA, and pltB, and 58.67% (71/121) of S. Telelkebir harbored antimicrobial-resistant gene fosaA7. The study by core genome multilocus sequence typing (cgMLST) and core single-nucleotide polymorphism (SNP)-based phylogenomic analysis demonstrated that the S. Telelkebir isolates from different sources and locations clustered together. This suggests that regular international travels might increase the likelihood of rapid and extensive transmissions of potentially pathogenic bacteria. For the first time, our study revealed the antimicrobial resistance, virulence patterns, and genetic diversity of the serovar S. Telelkebir isolate in humans and similar isolates over the world. The present study also suggests that genomic investigation can facilitate surveillance and could offer added knowledge of a previously unknown threat with the unique combination of virulent and antimicrobial-resistant determinants.

Occurrence of mcr-mediated colistin resistance in Salmonella clinical isolates in Thailand

Nontyphoidal Salmonella, an important zoonotic pathogen and a major cause of foodborne illnesses, could be a potential reservoir of plasmids harbouring mobile colistin resistance gene (mcr). This study reported, for the first time, a high rate of mcr-carrying Salmonella clinical isolates (3.3%, 24/724) in Thailand, associated with mcr-3 gene (3.0%, 22/724) in S. 4,[5],12:i:-(15.4%, 4/26), S. Typhimurium (8.8%, 5/57), and S. Choleraesuis (5.6%, 13/231). Remarkably, the increasing trends of colistin and extended-spectrum cephalosporin resistances have displayed a high agreement over the years, with a dramatic rise in the mcr-carrying Salmonella from 1.1% (6/563) during 2005–2007 to 11.2% (18/161) during 2014–2018 when CTX-M-55 became abundant. Clonal and plasmid analysis revealed that the self-transferable IncA/C and a novel hybrid IncA/C-FIIs MDR plasmids were the major vehicles to disseminate both mcr-3 and blaCTX-M55 genes among diverse Salmonella strains, from as early as 2007. To our knowledge the occurrence of mcr-3 and the co-existence of it with blaCTX-M-55 in S. Choleraesuis are reported here for the first time, leading to clinical concern over the treatment of the invasive salmonellosis. This study provides evidence of the potential reservoirs and vectors in the dissemination of the mcr and highlights the co-selection by colistin and/or cephalosporins.

Salmonella Typhimurium DT 104 response to Lytic bacteriophage and Lactobionic acid on raw chicken breast

Bacterial food poisoning cases due to Salmonella have been linked with a variety of poultry products. This study evaluated the effects of a Salmonella-specific Lytic bacteriophage and Lactobionic acid (LBA) on Salmonella Typhimurium DT 104 growth on raw chicken breast meat. Each chicken breast was randomly assigned to a treatment group (Control, DI water, phage 1%, phage 5%, LBA 10 mg/mL, LBA 20 mg/mL, and phage 5% + LBA 20 mg/mL) with four chicken breasts per group. Samples were inoculated with 106 CFU/mL of Salmonella and stored at 4 °C for 30 min. The inoculated chicken breasts were randomly assigned to different storage time (0 h, 1 h, 24 h, or 48 h). Both time and treatment showed significance reduction (P < 0.0001) of microbial growth. The weight loss was significantly different (P < 0.0001) between treatments. The LBA treatments were not effective when compared to the control group, but Lytic bacteriophage significantly reduced the amount of microbial growth.

Critical occurrence of verotoxgenic E.coli and non-typhoidal salmonella in some heat treated dairy products.

Pathogenic strains of E.coli and Salmonella are common causes of foodborne illness and have been frequently isolated from inadequately heat-treated milk products in Mansoura city. The current study was performed to explore the prevalence of E.coli and Salmonella spp. in heattreated milk products intended for consumption in Mansoura university hospitals and hostels, as well as, to investigate their serotypes and virulence potential. Seventyfive samples of heat-treated milk products (Soft cheese, yoghurt, and processed cheese, 25 of each) were randomly gathered and directed to further investigation using conventional and molecular microbiology. Result revealed that 3(12%) of soft cheese samples harbored E.coli O146:H21, O26:H11 and O128:H2 serotypes and 2(8%) of yoghurt samples were contaminated with O128:H2 and O121:H7 serotypes while 3(12%) of processed cheese samples were positive for non-typhoidal Salmonella (NTS) serovars (Salmonella Typhimurium, Salmonella Infantis and Salmonella Essen). Virulence gene profiling reported that all E.coli isolates harbored eaeA gene and only E.coli O26:H11 and O121:H7 encoded stx2 (verotoxin) gene. Further, all Salmonella isolates harbored invA and stn genes, while only Salmonella Typhimurium and Salmonella Infantis encoded spvC gene. This study confirmed the existence of highly pathogenic verotoxogenic E.coli (VTEC) and NTS in investigated milk products which could be hazardous for public health and resident in Mansoura hospitals and hostels. Hence, the implementation of good hygienic practices together with hazard analysis, and risk-based preventive control measures are rigorously required in the process of HACCP plan to eliminate the risk of contamination that may occur during the manufacturing process.

Risk Assessment of Norovirus Illness from Consumption of Raw Oysters in the United States and in Canada.

Human norovirus (NoV) is the leading cause of foodborne illness in the United States and Canada. Bivalve molluscan shellfish is one commodity commonly identified as being a vector of NoV. Bivalve molluscan shellfish are grown in waters that may be affected by contamination events, tend to bioaccumulate viruses, and are frequently eaten raw. In an effort to better assess the elements that contribute to potential risk of NoV infection and illness from consumption of bivalve molluscan shellfish, the U.S. Department of Health and Human Services/Food and Drug Administration (FDA), Health Canada (HC), the Canadian Food Inspection Agency (CFIA), and Environment and Climate Change Canada (ECCC) collaborated to conduct a quantitative risk assessment for NoV in bivalve molluscan shellfish, notably oysters. This study describes the model and scenarios developed and results obtained to assess the risk of NoV infection and illness from consumption of raw oysters harvested from a quasi‐steady‐state situation. Among the many factors that influence the risk of NoV illness for raw oyster consumers, the concentrations of NoV in the influent (raw, untreated) and effluent (treated) of wastewater treatment plants (WWTP) were identified to be the most important. Thus, mitigation and control strategies that limit the influence from human waste (WWTP outfalls) in oyster growing areas have a major influence on the risk of illness from consumption of those oysters.

Increased Incidence of Antimicrobial-Resistant Nontyphoidal Salmonella Infections, United States, 2004-2016.

Salmonella is a major cause of foodborne illness in the United States, and antimicrobial-resistant strains pose a serious threat to public health. We used Bayesian hierarchical models of culture-confirmed infections during 2004–2016 from 2 Centers for Disease Control and Prevention surveillance systems to estimate changes in the national incidence of resistant nontyphoidal Salmonella infections. Extrapolating to the United States population and accounting for unreported infections, we estimated a 40% increase in the annual incidence of infections with clinically important resistance (resistance to ampicillin or ceftriaxone or nonsusceptibility to ciprofloxacin) during 2015–2016 (≈222,000 infections) compared with 2004–2008 (≈159,000 infections). Changes in the incidence of resistance varied by serotype. Serotypes I 4,[5],12:i:- and Enteritidis were responsible for two thirds of the increased incidence of clinically important resistance during 2015–2016. Ciprofloxacin-nonsusceptible infections accounted for more than half of the increase. These estimates can help in setting targets and priorities for prevention.

A Long-Range and Self-Powered Intelligent Food Monitoring System Based on Far-Field Energy Harvesting and Pressure Measurement

Introduction In recent decades, food safety is becoming a top concern in the world because it is directly related to human health. According to World Health Organization statistics, about 550 million people are poisoned each year because of unsafe food consumption. One of the leading causes of foodborne illnesses is the consumption of rotten and expired foods. Therefore, the development of a food monitoring system is essential. Indeed, many studies have focused on developing battery-free food monitoring systems based on radio frequency energy harvesting (RFEH) technology due to its benefits such as durability, low cost, and safety for stored food [1]-[2]. The major disadvantage of these studies is that they estimated food quality using gas sensors, which require large energy consumption (typically over 10mW). Moreover, the gas sensors need a long time to heat up to obtain accurate sensor data. These drawbacks reduce the feasibility of implementing these systems in practice.This paper aims to develop a self-powered battery-free food monitoring system based on far-field RFEH technique and pressure measurement, which can overcome the problems with the conventional methods. Methods and Experiments The overview architecture of our proposed system is depicted in Fig.1. The self-powering capability of the sensor tag is provided by converting the radio wave transmitted from an RF generator into electrical signals. The antenna is the first component and plays a vital role in an energy harvesting system. To improve the received power and enhance the distance of power transfer, we have developed a printed Yagi-Uda Three element (driver, director, and reflector) because of its simplicity in design, high gain, compact size, and low cost [3]. The operating frequency of the antenna is chosen at the unlicensed Industrial Scientific Medical (ISM) band of 915MHz. Besides, in this study, we focus on monitoring the gradual increase of the air pressure inside the food container due to gas emission during food degradation. The air pressure sensor has ultra-low energy consumption and high precision, suitable for the limited energy condition of far-field RFEH system. Finally, we conduct a set of experiments with different sorts of food, such as pork, fish, and chicken, to demonstrate the feasibility of the proposed method. Results and Conclusions As a result, the designed Yagi antenna has a high gain of 6.54dBi in the direction of the maximum radiation, better than the isotropic antenna in some conventional systems that usually achieve about 1.7 dBi [1]. The reflection coefficient of the Yagi-Uda antenna achieved -26.8dB and voltage standing wave ratio (VSWR) better than 1.3 in approximately 60 band (890-950 MHz). At a distance of 6 meters, the harvested RF power reach -10.9dBm , and the rectifying voltage was obtained at 380mV , which is high enough for the tag to launch its functions. The sensor unit is designed with ultra-low power components and consumes only 300μW on average. The air pressure, temperature, and humidity data obtained from the sensor tag are used to evaluate and estimate the food quality, demonstrating the proposed method's effectiveness.

Prevalence, Risk Factors, and Antibiogram of Nontyphoidal Salmonella from Beef in Ambo and Holeta Towns, Oromia Region, Ethiopia.

Background Salmonella has been recognized as a major cause of food-borne illness associated with the consumption of food of animal origin. The present cross-sectional study was conducted from December 2017 to May 2018 in Ambo and Holeta towns to assess the prevalence, risk factors, and antimicrobial susceptibility patterns of nontyphoidal Salmonella isolates from raw beef samples from abattoirs, butchers, and restaurants in Ambo and Holeta towns, Oromia region, Ethiopia. Methods A total of 354 beef samples were collected from abattoirs, butchers, and restaurants. Salmonella isolation and identification were carried out using standard bacteriological methods recommended by the International Organization for Standardization. Antimicrobial susceptibility testing was performed using the disk diffusion method. Besides, a structured questionnaire was used to collect sociodemographic data and potential risk factors for contamination of meat. Chi-square tests and logistic regression were used for data analyses. Results Of the total 354 meat samples examined, 20 (5.7%, 95% confidence interval (CI): 3.5–8.6) were positive for Salmonella. Two serotypes belonging to S. typhimurium (11 isolates) and I:4,5,12: i:- (9 isolates) were identified. The Salmonella detection rate in abattoirs, butchers, and restaurants was 4.2% (5/118), 8.5% (10/118), and 4.2% (5/118), respectively. The antimicrobial susceptibility test showed that 40%, 30%, and 20% of the Salmonella isolates were resistant to azithromycin, amoxicillin, and ceftriaxone, respectively. The odds of Salmonella isolation when meat handlers are illiterate were 7.8 times higher than those when they are educated to the level of secondary and above (P=0.032). Similarly, the likelihood of Salmonella isolation was 6.3 and 7.6 times higher among workers of butcher and restaurants, respectively, who had no training (P=0.003) and no knowledge (P=0.010) on food safety and hygiene. Conclusions The study showed widespread multidrug-resistant Salmonella isolates in the study areas. Therefore, raw meat consumption and indiscriminate use of antimicrobial drugs should be discouraged. Provision of food safety education for meat handlers and further surveillance of antimicrobial-resistant isolates are suggested.

Development of a recombinase-aided amplification assay for rapid detection of human norovirus GII.4

BackgroundHuman noroviruses are one of the main causes of foodborne illnesses and represent a serious public health concern. Rapid and sensitive assays for human norovirus detection are undoubtedly necessary for clinical diagnosis, especially in regions without more sophisticated equipment.MethodThe rapid reverse transcription recombinase-aided amplification (RT-RAA) is a fast, robust and isothermal nucleic acid detection method based on enzyme reaction. This method can complete the sample detection at 39 °C in 30 min. In this study, we successfully established a rapid reverse transcription recombinase-aided amplification (RT-RAA) assay for the detection of human norovirus GII.4 and applied this assay to clinical samples, as well as comparison with commercial reverse transcription real-time fluorescence quantitative PCR (RT-qPCR).ResultsAt 95% probability, the detection sensitivity of RT-RAA was 3.425 log10 genomic copies (LGC)/reaction. Moreover, no cross-reaction was observed with other norovirus genogroups and other common foodborne viruses. Stool samples were examined by RT-RAA and reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). Compared of RT-qPCR, kappa values for human norovirus detection with RT-RAA were 0.894 (p < 0.001), indicating that both assays were in agreement.ConclusionThis RT-RAA assay provides a rapid, specific, and sensitive assay for human norovirus detection and is suitable for clinical testing.

PCR Primers for Screening Food for Verotoxin-Producing Escherichia coli, Inclusive of Three vt1 and Seven vt2 Subtypes

Verotoxin-producing Escherichia coli (VTEC; also known as Shiga toxin-producing E. coli) is a significant cause of foodborne illnesses around the world. Due to the serological and genomic diversity of VTEC, methods of detection for VTEC in food samples require detection of verotoxin or its gene vt (also known as stx). The current taxonomy of vt identifies three vt1 (a, c, d) and seven vt2 (a to g) subtypes. PCR detection of vt is convenient and rapid, but protocols may not detect all currently identified variants or subtypes of vt. The Health Canada Compendium of Analytical Methods protocol for the analysis of food for VTEC is MFLP-52. MFLP-52 includes a VT Screening PCR that is used to determine the presumptive presence of VTEC by the detection of vt in food enrichments and to differentiate VTEC from other isolates. The VT Screening PCR was developed prior to the establishment of the current vt taxonomy. An evaluation of VT Screening PCR for detection of the 10 established vt subtypes was performed, and it was discovered that the method could not detect subtypes vt1d and vt2f. Additional primers and a modified protocol were developed, and the modified VT Screening PCR was tested against an inclusivity panel of 50 VTEC strains, including representatives of 10 vt subtypes, and an exclusivity panel of 30 vt-negative E. coli from various sources, to ensure specificity. The reliability of MFLP-52 with the modified VT Screening PCR was assessed by analysis of four priority food matrices (ground beef, lettuce, cheese, and apple cider) inoculated with a VTEC strain at 2 to 5 CFU/25 g. The modified VT Screening PCR was determined to be able to detect all 10 vt subtypes and reliably detect the presence of VTEC in all tested food enrichments.

Library Preparation Based on Transposase Assisted RNA/DNA Hybrid Co-Tagmentation for Next-Generation Sequencing of Human Noroviruses.

Human noroviruses (HuNoVs) are one of the leading causes of foodborne illnesses globally. The viral genome is the most essential information for viral source tracing and viral transmission pattern monitoring. However, whole genome sequencing of HuNoVs is still challenging due to the sequence heterogeneity among different genotypes and low titer in samples. To address this need, in this study, the Transposase assisted RNA/DNA hybrid Co-tagmentation (TRACE-seq) method was established for next generation sequencing library preparation of HuNoVs. Our data demonstrated that almost the whole HuNoVs genome (>7 kb) could be obtained from all of the 11 clinical samples tested. Twelve genotypes including GI.3, GI.4, GI.5, GI.8, GII.2, GII.3, GII.4, GII.6, GII.12, GII.13, GII.14, and GII.21 were involved. Compared with the traditional method for viral metagenomics library preparation, optimized TRACE-seq greatly reduced the interference from the host’s and bacterial RNAs. In addition, viral genome sequences can be assembled by using less raw data with sufficient depth along the whole genome. Therefore, for the high versatility and reliability, this method is promising for whole viral genome attainment. It is particularly applicable for the viruses with a low titer that are mixed with a complicated host background and are unable to be cultured in vitro, like the HuNoVs utilized in this study.

Work-related increases in titer of Campylobacter jejuni antibody among workers at a chicken processing plant in Miyazaki prefecture, Japan, independent of individual ingestion of edible raw chicken meat.

Workers in poultry abattoirs may be frequently exposed to Campylobacter jejuni, which is a leading cause of bacterial food poisoning in Japan. The present study was conducted to measure the titers of IgG and IgA antibodies against C. jejuni among 104 female workers in a chicken processing plant in Miyazaki prefecture, Japan. Information regarding habitual ingestion of raw chicken meat and potential occupational risk factors was collected using a questionnaire. Acid extracts of four C. jejuni strains representing the genotypes most dominant in Miyazaki were used as antigens. The levels of both immunoglobulins measured by ELISA were not correlated with ingestion of edible raw chicken meat, the amount consumed in one sitting, or its frequency. Although age was correlated with antibody levels, the length of employment was not. Furthermore, the IgG and IgA levels in workers at the evisceration step were significantly higher than those at other locations in the plant. To identify the bacterial proteins recognized by the workers’ IgG and IgA antibodies, Western blotting followed by LC/MS was conducted. Flagellin was identified as the common protein recognized in the sera of workers for whom ELISA demonstrated both the highest and lowest antibody levels. We concluded that the titers of IgG and IgA against C. jejuni in workers at the processing plant had been increased by occupational exposure to Campylobacter, regardless of raw chicken meat ingestion.

COVID ‐19 transmission in cold chain: A safe and green new‐generation cold chain is demanded

<scp>COVID</scp> ‐19 transmission in cold chain: A safe and green new‐generation cold chain is demanded

Prevalence of classical Staphylococcal enterotoxin genes of Staphylococcus aureus isolated from ready-to-eat food in Ho Chi Minh City, Vietnam

Contamination of Staphylococcus aureus in ready-to-eat (RTE) food is a leading cause of foodborne illness in Vietnam. The aim of this study was to analyze the frequency of classical Staphylococcal enterotoxin genes (sea, seb, sec, sed, and see genes) in S. aureus strains isolated from ready-to-eat food in Ho Chi Minh, Vietnam (76 strains of&amp;nbsp; S. aureus were isolated from 200 random samples of ready - to - eat (RTE) food, which include pate, pork roll, barbecue pork, roasted pork and roasted duck, 40 samples of each), all the samples were collected from different fast food services on street in district 5, 6, 7 and 8 in Ho Chi Minh City, Vietnam. All the trains of S. aureus were stored at -70oC for analyzing Staphylococcal enterotoxin genes). The obtained results in this study indicated that out of 76 S. aureus strains, there are 6 strains (7.9%) carried SE genes: &amp;nbsp;sea gene (1.32%) was detected in one pate sample (Dist. 8), sec gene was detected (3.95%) in three samples, which are two pork roll samples (Dist. 7 and 8) and one roasted duck sample (Dist. 8), and finally see gene was detected in one pate sample (Dist. 8)and in one pork roll sample (Dist.&amp;nbsp; 8). This could be a serious public health risk and highlight the need to implement good hygiene practices.

A Monoclonal Antibody against the C-Terminal Domain of Bacillus cereus Hemolysin II Inhibits HlyII Cytolytic Activity.

Bacillus cereus is the fourth most common cause of foodborne illnesses that produces a variety of pore-forming proteins as the main pathogenic factors. B. cereus hemolysin II (HlyII), belonging to pore-forming β-barrel toxins, has a C-terminal extension of 94 amino acid residues designated as HlyIICTD. An analysis of a panel of monoclonal antibodies to the recombinant HlyIICTD protein revealed the ability of the antibody HlyIIC-20 to inhibit HlyII hemolysis. A conformational epitope recognized by HlyIIC-20 was found. by the method of peptide phage display and found that it is localized in the N-terminal part of HlyIICTD. The HlyIIC-20 interacted with a monomeric form of HlyII, thus suppressing maturation of the HlyII toxin. Protection efficiencies of various B. cereus strains against HlyII were different and depended on the epitope amino acid composition, as well as, insignificantly, on downstream amino acids. Substitution of L324P and P324L in the hemolysins ATCC14579T and B771, respectively, determined the role of leucine localized to the epitope in suppressing the hemolysis by the antibody. Pre-incubation of HlyIIC-20 with HlyII prevented the death of mice up to an equimolar ratio. A strategy of detecting and neutralizing the toxic activity of HlyII could provide a tool for monitoring and reducing B. cereus pathogenicity.

Molecular Analysis of Some Virulence Genes of Salmonellae Isolated from Chicken at Sharkia Governorate

Poultry is one of the most reservoirs of Salmonella that can be transmitted to humans through the food chain causing high risk bacterial food poisoning. In the present study, bacteriological examination of 200 samples from broiler internal organs (liver,2ceci, un absorbed yolk sac) from1 day old chicks suffering from omphalitis and respiratory disorders after hatching, revealed 26 Salmonella isolates 13%. Serotyping of 26 Salmonella isolates by slide agglutination test using specific monovalent and polyvalent O and H Salmonella sera revealed eleven different Salmonella serotypes, with S. Enteritidis as the most prevalent serotype (38.5%) followed by S.Tamale (23.07%). ,S. Typhymurium (19.2%), S. Kentucky (15.4%)and ,S.Heldberg (3.8%).most Salmonella isolates were sensitive to Ciprofloxacin ,sulfa methoxasole – trimethoprime , Chlorumphenicol and gentamycin .while they were resistant to Erythromycin ,Rifamycin , Amoxycillin /clavulinic acid ,colistin sulfate and cefotaxime . PCR detection of 6verulant genes of 5 strains of Salmonella isolates which proved to play an important role in the virulence of Salmonella in chicken. In this study detection of (invA gene, hilA gene, stn gene, spvc gene, fmH gene and pefA gene) is with percentages of (100%, 80%, 100%, 0%, 100% and 40%)respectively. From examined 5MDR Salmonella isolates, Integron class1were detected in all of them (100%) but no strain was found to harbor Integron class2.

Metabolic profile of listeriolysin- and non-listeriolysin producing strains of Listeria monocytogenes using Phenotype Microarray™ Technology

Background: Listeria monocytogenes remains a significant cause of foodborne illness that can be a potentially life threatening disease with high fatality rate in immunocompromised individuals. This disease, listeriosis is caused by the virulence factor, listeriolysin O (LLO) encoded by gene hly and two phospholipase C enzymes (PlcA and PlcB) encoded by the genes plcA and plcB respectively. LLO causes toxicity by pore formation, allowing the escape of L. monocytogenes from the vacuole of host cell such as phagolysosome. The replication of LLO is critical in pathogenesis. Methods & Materials: L. monocytogenes ATCC 19111 (LLO producer) and L. monocytogenes ATCC 15313 (non-LLO producer) were selected to profile the metabolic differences in order to determine the substrates utilization and their metabolic pathway that may affect the production of LLO, using Phenotype Microarray (PM) technology. Four PM assays were conducted using PM 1 to PM 4 plates (PM 1 and 2: carbon utilization assay, PM 3: nitrogen utilization assay and PM 4: phosphorus–sulphur utilization assay). Results: There are significant differences in metabolic profile among two strains, particularly in carbon utilization assay. In PM1 and PM2 plates, total of 190 carbon sources, eight substrates (4.2%) were found to have the capability in producing LLO. In PM3 plate containing 95 nitrogen sources, four substrates (4.2%) were found being utilized by LLO producer and none in PM4. Various studies had proven a significant increment in hemolytic activity of LLO through tricarbocylic acid cycle (TCA) and pyruvate metabolism by carbons supplementation. In this study, L-Malate had drawn our attention in synthesizing LLO indirectly through various pathway, including TCA, carbon metabolism, two component system and aminoacyl-tRNA biosynthesis. Conclusion: PM technology is simple, bioinformative and useful for screening of physiological differences between two strains. L-Malate acts as a key of listeriosis-causing agent which involved in production of virulence factor. It is important to understand the metabolic profile of L. monocytogenes to minimize their toxicity.

Epidemiology of Campylobacter jejuni in raccoons (Procyon lotor) on swine farms and in conservation areas in southern Ontario.

Campylobacter is a leading cause of foodborne illness in humans worldwide. Sources of infection are often difficult to identify, and are, generally, poorly understood. Recent work suggests that wildlife may represent a source of Campylobacter for human infections. Using a repeated cross-sectional study design, raccoons were trapped on five swine farms and five conservation areas in southern Ontario from 2011 to 2013. Our objectives were to: (a) assess the impact of seasonal, climatic, location, annual and raccoon demographic factors on the occurrence of Campylobacter jejuni in these animals; and (b) identify clusters of C.jejuni in space, time and space-time using spatial scan statistics. Multi-level multivariable logistic regression was used to examine the odds of isolating C.jejuni, with site and animal modelled as random intercepts. The following independent variables were examined: raccoon age and sex, year, location type, season, temperature and rainfall. A total of 1,096 samples were obtained from 627 raccoons; 46.3% were positive for C.jejuni. The following interactions and their main effects were significant (p<.05) and retained in the final model: season×temperature, year×rainfall, year×temperature. Based on the results from our multivariable model and spatial scan statistics, climatic variables (i.e. rainfall, temperature and season) were associated with the carriage of C.jejuni by raccoons, but the effects were not consistent, and varied by location and year. Although raccoons may pose a zoonotic risk due to their carriage of Campylobacter, further work is required to characterize the transmission and movement of this microorganism within the ecosystem.

Antimicrobial efficacy of nisin, oregano and ultrasound against Escherichia coli O157:H7 and Listeria monocytogenes on lettuce

Ready-to-eat vegetables such as lettuce are prone to bacterial contamination, predominantly from Escherichia coli and Listeria monocytogenes, the leading causes of foodborne illnesses globally. Chlorine is widely used as a decontaminant in the fresh produce industry, however, potential carcinogenic risks limit its usage. As an alternative, green methods and hurdle technology are gaining interest. In this paper, the efficacy of a combination of nisin, oregano and ultrasound on the reduction of E. coli and L. monocytogenes on lettuce was studied using response surface methodology/Box-Behnken model design, and was found to be reliable (p < 0.05). A combination of 771.2 IU/g nisin, 0.185% v/v oregano and 14.65 min ultrasound was the most effective treatment on both pathogens, showing log reductions of 3.43 and 9.20 CFU/mL for E. coli and L. monocytogenes, respectively. The treated lettuce samples did not show any significant differences in textural properties; however, mild colour changes and a slight increase in the electrolyte leakage rate was observed, within permissible limits. Interestingly this is the first report on the combination of nisin, oregano and ultrasound, as a promising alternative to chemical treatments for the reduction of E. coli and L. monocytogenes on lettuce, without compromising its appearance and quality.