Common Causes Of Foodborne Illness Research Articles

Effects of Nettle (Urtica dioica) Extract on Versus Pathogenic Microorganisms in Yogurt Production

Contamination with pathogenic bacteria is the most common cause of foodborne illness and represents a public health problem worldwide. These pathogens can be controlled by adding extracts to fermented milk. In the present study, the effects of nettle extract on selected pathogenic bacteria in yogurt production were investigated. For this purpose, the antibacterial effectiveness of the extract additives in the presence of bacteria was examined and compared. Yoghurt samples, 24 different samples contaminated with 7 standard pathogen strains, were analyzed for chemical properties (pH and acidity) and antimicrobial activity after 1, 7, 14 and 21 days of storage at 4 °C. In particular, it was found that the decrease in pH and increase in acidity in the nettle extract samples after 21 days were significantly greater than in natural yogurt and yogurt samples containing nettle extract (0.5% and 1%, respectively) (p

Synthesis of Piperidine Conjugated Quinoxalines as Potential Antibiofilm Agents

Background: The most common cause of food-borne illness is bacterial or viral contamination. Although there are several therapeutics available to combat these microbes, they lost their efficacy in long-term medication. Because, over a period of time, microbes developed resistance against drugs and this antimicrobial resistance is a serious threat to global public health as a consequence of the widely disseminated and careless use of antimicrobials. Therefore, there is a need to develop some new chemical moieties with a safety factor and better efficacy. A series of substituted N-(1-benzylpiperidin-4- yl)quinoxalin-2-amines (5a-j) (5ab, 5ac) were synthesized and screened for their in vitro antibacterial activity against Salmonella paratyphi, a well-known food-borne pathogen. Methods: Experimental methods, agar diffusion and broth microdilution assays were carried out to evaluate the antibacterial activity of the lead compounds. Further, antibiofilm methods, crystal violet, and MTT assays were subjected to investigate their biofilm inhibition capacity against S. paratyphi. Results: Among the tested compounds, 5b, 5e, 5h, and 5j bearing 4-chloro, 3,4-dimethoxy, 4-methyl and thienyl groups on the phenyl ring of quinoxalines emerged as potential candidates having significant antisalmonella activity. In these four potential candidates, compounds 5b and 5h were effective against Salmonella whereas compounds 5e and 5j effectively inhibited the biofilm formation of Salmonella. Conclusion: N-(1-benzylpiperidin-4-yl)quinoxalin-2-amines (5a-j) (5ab, 5ac) were synthesized and evaluated for antisalmonella activity against S. paratyphi. Among the series of compounds, four compounds significantly showed good activity and emerged as antibacterial agents for further studies in the future.

A foodborne outbreak linked to Bacillus cereus at two middle schools in a rural area of Chongqing, China, 2021.

Bacillus cereus (B. cereus) is a common cause of foodborne illness. An outbreak of acute gastrointestinal illness occurred at two middle schools in a rural region of Chongqing, China, in 2021. This study aimed to elucidate the outbreak's characteristics, identify risk factors, and determine the source of contamination. A retrospective cohort study and an environmental investigation were conducted. Vomit samples, anal swabs, and food samples were collected and tested by RT-PCR for 18 species of bacteria and viruses, including B. cereus. Positive samples of B. cereus underwent biochemical experiments and bacterial quantification. A total of 198 cases were reported in this outbreak, with an attack rate of 24.63%. The main symptoms were vomiting (100%), bellyache (83.33%), and dizziness (62.63%). The retrospective cohort study showed a significant association between the outbreak and rice noodles provided by a nearby food manufacturer (RR = 39.63, p < 0.001). B. cereus was detected in 20 vomit samples, three anal swabs, and seven rice noodles samples, with a count exceeding 103 CFU/g. These findings strongly suggested that the outbreak was linked to B. cereus-contaminated rice noodles. Enhancing food safety surveillance and promoting health measures among schools and food manufacturers in rural areas is crucial to prevent similar incidents in the future in Chongqing, China.

Modeling the risk of Vibrio parahaemolyticus in oysters in Taiwan by considering seasonal variations, time periods, climate change scenarios, and post-harvest interventions

Vibrio parahaemolyticus is a halophilic gram-negative bacterium commonly found in marine environments, particularly in warm coastal waters. This pathogen has been reported as a common cause of foodborne illness associated with the consumption of raw or undercooked seafood. The presence and density of this bacterium in seafood are often associated with the climatological conditions of the marine environment. Herein, we developed the quantitative risk assessment model for Vibrio parahaemolyticus in oysters in Taiwan by considering seasonal variations, time periods, climate change scenarios, and post-harvest interventions. This study showed that season, time period, shared socioeconomic pathway (SSP), and post-harvest intervention significantly influenced the risk level of becoming ill from consuming oysters. The mean estimates of risk in winter, spring, summer, and fall were estimated to be 9.1 × 10−5, 2.0 × 10−3, 2.0 × 10−2, 6.9 × 10−3 per serving, respectively. Our models predict that, if global temperatures continue to increase in the coming decades due to climate change, the risk per serving of oysters is likely to increase by 18-145% by 2041-2060 and by 18-718% by 2081-2100, depending on the season and SSP. The application of thermal processing or high hydrostatic pressure processing was found to be the most effective approach in reducing risk, even under the threat of increasing global temperatures.

Identifying Predictors of Safe Food Handling Practices among Canadian Households with Children Under Eighteen Years

Poor food handling practices at home are a common cause of foodborne illness. Children are more susceptible to foodborne illness than adults. Because children’s food safety depends on the safe food handling practices of parents and caregivers, this study aims to identify determinants of safe food handling practices among Canadian families with children under 18 years. Data for Canadian households with children (n = 294) were extracted from a larger telephone survey conducted across all Canadian provinces and territories between 2014 and 2015. Four food safety practice outcomes and six demographic variables were examined using multivariable logistics regression. Most survey participants were females (56%) who had less than a bachelor’s degree (67%) and were caring for one child (55%). Approximately 90% of caregivers reported proper hand hygiene, and 79% refrigerated leftovers within 2 h of cooking. Only 33% of caregivers reported preventing cross-contamination, and fewer reported using food thermometers for poultry cuts (13%) and hamburgers (11%). Those in the higher income and education categories were less likely to follow safe food handling practices such as hand hygiene and safe refrigeration of leftovers. This research highlights the need for food safety interventions that target Canadian families with children within certain demographic groups.

Identifying Predictors of Safe Food Handling Practices among Canadian Households with Children Under Eighteen Years

Poor food handling practices at home are a common cause of foodborne illness. Children are more susceptible to foodborne illness than adults. Because children’s food safety depends on the safe food handling practices of parents and caregivers, this study aims to identify determinants of safe food handling practices among Canadian families with children under 18 years. Data for Canadian households with children (n = 294) were extracted from a larger telephone survey conducted across all Canadian provinces and territories between 2014 and 2015. Four food safety practice outcomes and six demographic variables were examined using multivariable logistics regression. Most survey participants were females (56%) who had less than a bachelor’s degree (67%) and were caring for one child (55%). Approximately 90% of caregivers reported proper hand hygiene, and 79% refrigerated leftovers within 2 h of cooking. Only 33% of caregivers reported preventing cross-contamination, and fewer reported using food thermometers for poultry cuts (13%) and hamburgers (11%). Those in the higher income and education categories were less likely to follow safe food handling practices such as hand hygiene and safe refrigeration of leftovers. This research highlights the need for food safety interventions that target Canadian families with children within certain demographic groups.

Distribution of Virulence Genes in Campylobacter spp. Isolated from Agaricus Mushrooms in Iran.

The white button mushroom (Agaricus) is a significant nutritional and therapeutic species utilized in the human diet and could transmit various bacterial infections. Campylobacter species are the most common cause of foodborne illness across the world. The present study has been planned to determine the frequency of virulence genes and antibiotic susceptibility test in Campylobacter spp. recovered from Agaricus mushroom. In this study, 740 Agaricus mushroom samples were gathered randomly from various markets from June 2020 to December 2020. Confirmation of Campylobacter spp. using biochemical analyses and 23S rRNA-based PCR was performed. The agar dilution technique was used to determine resistance to antibiotics using gentamicin (GM10μg), ciprofloxacin (CIP5μg), nalidixic acid (NA30μg), tetracycline (TE30μg), ampicillin (AM10μg), amoxicillin+ clavulanic acid (AMC30μg), erythromycine (E15μg), azithromycin (AZM15μg), clindamycin (CC2μg), and chloramphenicol (C30μg). Multiplex PCR was utilized to determine the prevalence of the recR, dnaJ, wlaN, virBll, cdtC, cdtB, cdtA, flaA, cadF, pidA, ciaB, ceuE, and cgtB genes. Campylobacter spp. were detected in 74 out of 740 Agaricus mushroom samples (10%). According to the data, Agaricus mushroom samples included 32 (4.32%) C. jejuni, 11 (1.48%) C. coli, and 31 (4.18%) other Campylobacter spp. Antimicrobial resistance was most common in C. jejuni isolates. C. jejuni isolates also had the lowest resistance rate to gentamycin, ciprofloxacin, and nalidixic acid. C. coli isolates were reported to have the highest antimicrobial resistance to ciprofloxacin, ampicillin, and erythromycine. Resistance to gentamycin and amoxicillin+ clavulanic acid was likewise lowest among C. coli strains. The flaA and ciaB genes were found in 100% of B-lactams-susceptible C. jejuni and C. coli strains. When examining the relationship between antibiotic resistance and the existence of virulence genes, it was observed that there is a statistically significant relationship (p < 0.001) between bacterial resistance and virulence genes. Our findings indicated that changes in resistance patterns in Campylobacter strains have emerged from multiple treatment approaches in Agaricus mushrooms.

Estimation of Bacteriophage MS2 Inactivation Parameters During Microwave Heating of Frozen Strawberries

Frozen berries have been repeatedly linked to acute gastroenteritis caused by norovirus, the most common cause of foodborne illness in the United States. Many guidelines recommend that frozen berries be microwaved for at least 2 min, but it is unclear if this thermal treatment is effective at inactivating norovirus. The objective of this study was to model the effect of microwave heating at varying power levels on the survival of bacteriophage MS2, a norovirus surrogate, when inoculated onto frozen strawberries. Bacteriophage MS2 was inoculated onto the surface of frozen strawberries with a starting concentration of approximately 10 log PFU/g. Samples (either 3 or 5 whole strawberries) were heated in a 1300-Watt domestic research microwave oven (frequency of 2450 MHz) at power levels of 30, 50, 70, and 100% (full power), for times ranging from 15 to 300 s to determine inactivation. Temperatures at berry surfaces were monitored during heating using fiberoptic thermometry. All experiments were conducted in triplicate. The primary model for thermal inactivation was a log-linear model of logN vs. time. The secondary model was for a D-value decreasing linearly with temperature and an added term that was path-dependent on the thermal history. Parameters in the model were estimated using dynamic temperature history at the surface of the berry, via nonlinear regression using all data simultaneously. The root mean square error was ∼0.5 PFU/g out of a total 6-log reduction. Log reductions of 1.1 ± 0.4, 1.5 ± 0.5, 3.1 ± 0.1, and 3.8 ± 0.2 log PFU/g were observed for 30, 50, 70, and 100% microwave power levels when three berries were heated for 60 s. D-values were 21.4 ± 1.95 s and 10.6 ± 1.1 s at 10 and 60°C, respectively. This work demonstrates an approach to estimate inactivation parameters for viruses from dynamic temperature data during microwave heating. These findings will be useful in predicting the safety effect of microwave heating of berries in the home or food service.

Efficacy of Antimicrobial Interventions Used in Meat Processing Plants against Antimicrobial Tolerant Non–Antibiotic-Resistant and Antibiotic-Resistant Salmonella on Fresh Beef

Salmonella is a common cause of foodborne illness in the United States, and several strains of Salmonella have been identified as resistant to antibiotics. It is not known whether strains that are antibiotic resistant (ABR) and that have some tolerance to antimicrobial compounds are also able to resist the inactivation effects of antimicrobial interventions used in fresh meat processing. Sixty-eight Salmonella isolates (non-ABR and ABR strains) were treated with half concentrations of lactic acid (LA), peracetic acid (PAA), and cetylpyridinium chloride (CPC), which are used in beef processing plants to screen for tolerant strains. Six strains each from non-ABR and ABR Salmonella that were most tolerant of LA (2%), PAA (200 ppm), and CPC (0.4%) were selected. Selected strains were inoculated on surfaces of fresh beef and subjected to spray wash treatment with 4% LA, 400 ppm PAA, or 0.8% CPC for the challenge study. Tissue samples were collected before and after each antimicrobial treatment for enumeration of survivors. Spray treatment with LA, PAA, or CPC significantly reduced non-ABR Salmonella and ABR Salmonella on surfaces of fresh beef by 1.95, 1.22, and 1.33 log CFU/cm2, and 2.14, 1.45, and 1.43 log CFU/cm2, respectively. The order of effectiveness was LA > PAA = CPC. The findings also indicated that LA, PAA, and CPC were equally (P ≤ 0.05) effective against non-ABR and ABR Salmonella on surfaces of fresh beef. These data contribute to the body of work that indicates that foodborne pathogens that have acquired both antibiotic resistance and antimicrobial tolerance are still equally susceptible to meat processing antimicrobial intervention treatments.

Direct Outpatient Health Care Costs Among Commercially Insured Persons for Common Foodborne Pathogens and Acute Gastroenteritis, 2012-2015.

Foodborne illness is common in the United States with most, but not all, foodborne pathogens causing symptoms of acute gastroenteritis (AGI). Outpatient care is the most frequent type of medical care sought; however, more accurate estimates of outpatient costs are needed to inform food safety policy decision. Using the U.S. MarketScan Commercial Claims and Encounters database, we quantified the per-visit cost of outpatient visits with any AGI-related diagnosis (including pathogen-specific and nonspecific or symptom-based diagnoses) and for those with a pathogen-specific diagnosis for 1 of 29 pathogens commonly transmitted through food (including pathogens that cause AGI and some that do not). Our estimates included the per-case cost of office visits and associated laboratory tests and procedures as well as the conservative estimates of prescription cost. Most AGI outpatient visits were coded using nonspecific codes (e.g., infectious gastroenteritis), rather than pathogen-specific codes (e.g., Salmonella). From 2012 to 2015, we identified more than 3.4 million initial outpatient visits with any AGI diagnosis and 45,077 with a foodborne pathogen-specific diagnosis. As is typical of treatment cost data, severe cases of illness drove mean costs above median. The mean cost of an outpatient visit with any AGI was $696 compared with the median of $162. The mean costs of visits with pathogen-specific diagnoses ranged from $254 (median $131; interquartile range [IQR]: $98-184) for Streptococcus spp. Group A (n = 22,059) to $1761 (median $161; IQR: $104-$1101) for Clostridium perfringens (n = 30). Visits with two of the most common causes of foodborne illness, nontyphoidal Salmonella and norovirus, listed as a diagnosis, had mean costs of $841 and $509, respectively. Overall, the median per-case costs of outpatient visits increased with age, with some variation by pathogen. More empirically based estimates of outpatient costs for AGI and specific pathogens can enhance estimates of the economic cost of foodborne illness used to guide food policy and focus prevention efforts.

Intra-species diversity of Clostridium perfringens: A diverse genetic repertoire reveals its pathogenic potential

Clostridium perfringens is the causative agent of many enterotoxic diseases in humans and animals, and it is present in diverse environments (soil, food, sewage, and water). Multilocus Sequence Typing (MLST) and Whole Genome Sequencing (WGS) have provided a general approach about genetic diversity of C. perfringens; however, those studies are limited to specific locations and often include a reduced number of genomes. In this study, 372 C. perfringens genomes from multiple locations and sources were used to assess the genetic diversity and phylogenetic relatedness of this pathogen. In silico MLST was used for typing the isolates, and the resulting sequence types (ST) were assigned to clonal complexes (CC) based on allelic profiles that differ from its founder by up to double-locus variants. A pangenome analysis was conducted, and a core genome-based phylogenetic tree was created to define phylogenetic groups. Additionally, key virulence factors, toxinotypes, and antibiotic resistance genes were identified using ABRicate against Virulence Factor Database (VFDB), TOXiper, and Resfinder, respectively. The majority of the C. perfringens genomes found in publicly available databases were derived from food (n = 85) and bird (n = 85) isolates. A total of 195 STs, some of them shared between sources such as food and human, horses and dogs, and environment and birds, were grouped in 25 CC and distributed along five phylogenetic groups. Fifty-three percent of the genomes were allocated to toxinotype A, followed by F (32%) and G (7%). The most frequently found virulence factors based on > 70% coverage and 99.95% identity were plc (100%), nanH (99%), ccp (99%), and colA (98%), which encode an alpha-toxin, a sialidase, an alpha-clostripain, and a collagenase, respectively, while tetA (39.5%) and tetB (36.2%), which mediate tetracycline resistance determinants, were the most common antibiotic resistance genes detected. The analyses conducted here showed a better view of the presence of this pathogen across several host species. They also confirm that the genetic diversity of C. perfringens is based on a large number of virulence factors that vary among phylogroups, and antibiotic resistance markers, especially to tetracyclines, aminoglycosides, and macrolides. Those characteristics highlight the importance of C. perfringens as a one of the most common causes of foodborne illness.

Risk Factors for Salmonella Contamination of Whole Chicken Carcasses following Changes in U.S. Regulatory Oversight

Salmonella is a common cause of foodborne illness in the United States and often is linked to chicken products. Salmonella contamination has been associated with meat processing facility characteristics, such as the number of employees (i.e., hazard analysis critical control point [HACCP]-based definition of size). The risk factors for Salmonella contamination in U.S. poultry have not been evaluated since implementation of the New Poultry Inspection System (NPIS) in 2014. The goal of this study was to determine whether risk factors for Salmonella contamination changed after implementation of the NPIS. Presence or absence of Salmonella in whole chicken carcasses was modeled using microbiological testing data collected from 203 poultry processing establishments by the U.S. Department of Agriculture Food Safety and Inspection Service between May 2015 and December 2019. A model was fit using generalized estimating equations for weekly presence or absence of Salmonella, and production volume, geographic location, and season were included as potential covariates among other establishment demographics. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated from the marginal model. Of the 40,497 analyzable samples, 1,725 (4.26%) were positive for Salmonella. Odds of contamination was lower among establishments slaughtering ≥10,000,000 birds per year (OR = 0.466; 95% CI, [0.307, 0.710]) and establishments producing ready-to-eat finished products (OR = 0.498; 95% CI, [0.298, 0.833]) and higher among establishments historically (previous 84 days) noncompliant with HACCP regulations (OR = 1.249; 95% CI, [1.071, 1.456]). Contamination also significantly varied by season and geographic region, with higher odds of contamination during summer and outside the MidEast Central region. These results support continuation of targeted food safety policies and initiatives promoting pathogen reduction by establishments with smaller volumes and those noncompliant with HACCP regulations.

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.

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.

Human Intestinal Enteroids to Evaluate Human Norovirus GII.4 Inactivation by Aged-Green Tea.

Human noroviruses are the leading cause of epidemic and sporadic acute gastroenteritis worldwide and the most common cause of foodborne illness in the United States. Several natural compounds, such as aged-green tea extract (aged-GTE), have been suggested as ingestible antiviral agents against human norovirus based on data using murine norovirus and feline calicivirus as surrogates. However, in vitro data showing their effectiveness against infectious human norovirus are lacking. We tested the activity of aged-GTE to inhibit human norovirus in a human intestinal enteroids (HIEs) model and Tulane virus in LLC-monkey kidney (LLC-MK2) cell culture. HIE monolayers pretreated with aged-GTE at different temperatures showed complete inhibition of human norovirus GII.4 replication at concentrations as low as 1.0 mg/ml for 37°C, 1.75 mg/ml for 21°C, and 2.5 mg/ml for 7°C. In contrast, a moderate decrease in Tulane virus infectivity of 0.85, 0.75, and 0.65 log TCID50/ml was observed for 2.5 mg/ml aged-GTE at 37, 21, and 7°C, respectively. Our findings demonstrate that GTE could be an effective natural compound against human norovirus GII.4, while only minimally effective against Tulane virus.

Detection of Salmonella typhimurium and Escherichia coli in artificially inoculated Milk sample using Real Time PCR method

Salmonella typhimurium and Escherichia coli are the bacteria the most common cause of food-borne illness. The aim of the study is to detection S. typhimurium and E. coli by Real Time PCR from milk samples. Gene targeted of S. typhimurium is pef and the E. coli is fimC. Confirmation test of all primers in contaminated milk with S. typhimurium and E. coli gave different cycle threshold (Ct) value in range 12-13. The detection limit for S. typhimurium with primer pef was in 7, 92 pg/μL and detection limit for E. coli with primer fimC in 7, 12 pg/μL. Each primer produces distinctive melting peak. The melting peak curve S. typhimurium with pef primer is 84,17°C and the melting peak curve E. coli with fimC primer is 79,97°C Based on the result of this study; all the primers were successfully applied in detecting S. typhimurium and E. coli bacteria in the milk sample quickly, sensitive and specific as well as can determine the number of bacteria accurately.

Capsular Polysaccharide Is a Receptor of a Clostridium perfringens Bacteriophage CPS1.

Clostridium perfringens is a Gram-positive, anaerobic, and spore forming bacterium that is widely distributed in the environment and one of the most common causes of foodborne illnesses. Bacteriophages are regarded as one of the most promising alternatives to antibiotics in controlling antibiotic-resistant pathogenic bacteria. Here we isolated a virulent C. perfringens phage, CPS1, and analysis of its whole genome and morphology revealed a small genome (19 kbps) and a short noncontractile tail, suggesting that CPS1 can be classified as a member of Picovirinae, a subfamily of Podoviridae. To determine the host receptor of CPS1, the EZ-Tn5 random transposon mutant library of C. perfringens ATCC 13124 was constructed and screened for resistance to CPS1 infection. Analysis of the CPS1-resistant mutants revealed that the CPF_0486 was disrupted by Tn5. The CPF_0486 was annotated as galE, a gene encoding UDP-glucose 4-epimerase (GalE). However, biochemical analyses demonstrated that the encoded protein possessed dual activities of GalE and UDP-N-acetylglucosamine 4-epimerase (Gne). We found that the CPF_0486::Tn5 mutant produced a reduced amount of capsular polysaccharides (CPS) compared with the wild type. We also discovered that glucosamine and galactosamine could competitively inhibit host adsorption of CPS1. These results suggest that CPS acts as a receptor for this phage.

1487. Recent Resurgence of Salmonellosis-Related Mortality in the United States, 1990–2015

BackgroundNon-typhoidal salmonellosis is one of the most common causes of foodborne illness in the United States. The objective of this study was to update the epidemiology of salmonellosis-related mortality in the United States by examining multiple-cause-of-death data (MCOD).MethodsMCOD data from the National Center for Health Statistics (NCHS) for the years 1990–2015 were analyzed. Mortality rates and 95% confidence intervals (CI) were calculated for age, sex, race/ethnicity, year, and state. Poisson regression models were used to examine temporal trends. Logistic regression was used to determine whether selected comorbid conditions were associated with salmonellosis-related deaths.ResultsOverall, 1,987 salmonellosis-related deaths (3.17%) were identified as an underlying and/or associated cause of death. The average annual age-adjusted mortality rate was 0.027 per 100,000 person-years. Salmonellosis mortality rates were higher among males with an age-adjusted rate ratio (RR) of 1.89 (95% CI, 1.79–2.01) compared with females. Mortality rates were higher among non-Hispanic Blacks and Asian/Pacific Islanders with an age-adjusted RR of 2.46 (95% CI, 2.19–2.77) and 2.06 (95% CI, 1.67–2.55) compared with Whites, respectively. The highest number of salmonellosis deaths were reported among the 75–84 year age group (n = 467; 24% of all cases). A significant decrease in trend was observed in age-adjusted salmonellosis mortality rates from 1990 to 2015. Since 2006, a significant increase of 66% in mortality rates was observed. Among selected comorbid conditions, HIV, acute renal failure, cancers affecting bone marrow, and diseases of the digestive system were associated with salmonellosis deaths with odds ratios of 11.51 (95% CI 8.78–15.10), 3.09 (95% CI, 2.01 = 4.75), 2.81 (95% CI, 1.67–4.74), and 2.82 (95% CI, 2.34–3.40), respectively.ConclusionSalmonellosis is an underlying and/or associated cause of death, especially among those with immune senescence and suppression. Despite a substantial decline in mortality rates, since 2006 rates have increased, a concerning trend. If rates continue to increase, an evaluation of Salmonella prevention efforts will be warranted.Disclosures All authors: No reported disclosures.

A robust human norovirus replication model in zebrafish larvae.

Human noroviruses (HuNoVs) are the most common cause of foodborne illness, with a societal cost of $60 billion and 219,000 deaths/year. The lack of robust small animal models has significantly hindered the understanding of norovirus biology and the development of effective therapeutics. Here we report that HuNoV GI and GII replicate to high titers in zebrafish (Danio rerio) larvae; replication peaks at day 2 post infection and is detectable for at least 6 days. The virus (HuNoV GII.4) could be passaged from larva to larva two consecutive times. HuNoV is detected in cells of the hematopoietic lineage and the intestine, supporting the notion of a dual tropism. Antiviral treatment reduces HuNoV replication by >2 log10, showing that this model is suited for antiviral studies. Zebrafish larvae constitute a simple and robust replication model that will largely facilitate studies of HuNoV biology and the development of antiviral strategies.

Analysis of the capacity of Salmonella enterica Typhimurium to infect the human Placenta

IntroductionSalmonella species are gram-negative facultative intracellular bacteria that are common causes of foodborne illness in North America. Infections by Salmonella during pregnancy are a significant cause of fetal loss in domestic livestock, and fetal and maternal mortality in mice. Furthermore, Salmonella infection is associated with miscarriage, stillbirth and preterm birth in pregnant women. Despite these collective associations, the extent to which Salmonella can infect the human placenta has not been investigated. MethodsHuman placental villous explants from several gestational ages were exposed to Salmonella enterica serovar Typhimurium (STm) ex vivo. Infection was assessed by colony forming unit assay and whole mount immunofluorescence (WMIF). ResultsViable bacteria were recovered from placental villous explants of all gestational ages tested, but the bacterial burden was highest in 1st trimester explants. Bacterial numbers did not change appreciably with time post-infection in explants from any gestational age examined, suggesting that STm does not proliferate in placental villi. Exposure of villous explants to STm strains defective for the type III secretion systems revealed that Salmonella pathogenicity island 1 is essential for optimal invasion. In contrast to placental explants, STm infected and proliferated within villous cytotrophoblast cells isolated from term placentas. WMIF demonstrated that STm was restricted primarily to the syncytiotrophoblast layer in infected placentas. DiscussionOur study demonstrates that STm can invade into the syncytiotrophoblast but does not subsequently proliferate. Thus, the syncytiotrophoblast may function as a barrier to STm infection of the fetus.