FoodNet: overview of a decade of achievement

Increased incidence of vibriosis in Maryland, U.S.A., 2006-2019

BACKGROUND

Vibrio spp. naturally occur in warm water with moderate salinity. Infections with non-cholera Vibrio (vibriosis) cause an estimated 80,000 illnesses and 100 fatalities each year in the United States. Climate associated changes to environmental parameters in aquatic ecosystems are largely promoting Vibrio growth, and increased incidence of vibriosis is being reported globally. However, vibriosis trends in the northeastern U.S. (e.g., Maryland) have not been evaluated since 2008.

METHODS

Vibriosis case data for Maryland (2006-2019; n = 611) were obtained from the COVIS database. Incidence rates were calculated using U.S. Census Bureau population estimates for Maryland. A logistic regression model, including region, age group, race, gender, occupation, and exposure type, was used to estimate the likelihood of hospitalization.

RESULTS

Comparing the 2006-2012 and 2013-2019 periods, there was a 39% (p = 0.01) increase in the average annual incidence rate (per 100,000 population) of vibriosis, with V. vulnificus infections seeing the greatest percentage increase (53%, p = 0.01), followed by V. parahaemolyticus (47%, p = 0.05). The number of hospitalizations increased by 58% (p = 0.01). Since 2010, there were more reported vibriosis cases with a hospital duration ≥10 days. Patients from the upper eastern shore region and those over the age of 65 were more likely (OR = 6.8 and 12.2) to be hospitalized compared to other patients.

CONCLUSIONS

Long-term increases in Vibrio infections, notably V. vulnificus wound infections, are occurring in Maryland. This trend, along with increased rates in hospitalizations and average hospital durations, underscore the need to improve public awareness, water monitoring, post-harvest seafood interventions, and environmental forecasting ability.

Prevalence of ciprofloxacin resistance and associated genetic determinants differed among Campylobacter isolated from human and poultry meat sources in Pennsylvania

Poultry is the primary source of Campylobacter infections and severe campylobacteriosis cases are treated with macrolides and fluoroquinolones. However, these drugs are less effective against antimicrobial-resistant strains. Here, we investigated the prevalence of phenotypic antimicrobial resistance and associated resistance genetic determinants in Campylobacter isolates collected from human clinical (N = 123) and meat (N = 80) sources in Pennsylvania in 2017 and 2018. Our goal was to assess potential differences in the prevalence of antimicrobial resistance in Campylobacter isolated from human and poultry meat sources in Pennsylvania and to assess the accuracy of predicting antimicrobial resistance phenotypes based on resistance genotypes. We whole genome sequenced isolates and identified genetic resistance determinants using the National Antimicrobial Resistance Monitoring System Campylobacter AMR workflow v2.0 in GalaxyTrakr. Phenotypic antimicrobial susceptibility testing was carried out using the E-Test and Sensititre CAMPYCMV methods for human clinical and poultry meat isolates, respectively, and the results were interpreted using the EUCAST epidemiological cutoff values. The 193 isolates were represented by 85 MLST sequence types and 23 clonal complexes, suggesting high genetic diversity. Resistance to erythromycin was confirmed in 6% human and 4% meat isolates. Prevalence of ciprofloxacin resistance was significantly higher in human isolates as compared to meat isolates. A good concordance was observed between phenotypic resistance and the presence of the corresponding known resistance genetic determinants.

A Novel Foodborne Illness Detection and Web Application Tool Based on Social Media

Foodborne diseases and outbreaks are significant threats to public health, resulting in millions of illnesses and deaths worldwide each year. Traditional foodborne disease surveillance systems rely on data from healthcare facilities, laboratories, and government agencies to monitor and control outbreaks. Recently, there is a growing recognition of the potential value of incorporating social media data into surveillance systems. This paper explores the use of social media data as an alternative surveillance tool for foodborne diseases by collecting large-scale Twitter data, building food safety data storage models, and developing a novel frontend foodborne illness surveillance system. Descriptive and predictive analyses of the collected data were conducted in comparison with ground truth data reported by the U.S. Centers for Disease Control and Prevention (CDC). The results indicate that the most implicated food categories and the distributions from both Twitter and the CDC were similar. The system developed with Twitter data could complement traditional foodborne disease surveillance systems by providing near-real-time information on foodborne illnesses, implicated foods, symptoms, locations, and other information critical for detecting a potential foodborne outbreak.

Human Listeriosis

Listeria monocytogenes is a Gram-positive facultative intracellular pathogen that can cause severe invasive infections upon ingestion with contaminated food. Clinically, listerial disease, or listeriosis, most often presents as bacteremia, meningitis or meningoencephalitis, and pregnancy-associated infections manifesting as miscarriage or neonatal sepsis. Invasive listeriosis is life-threatening and a main cause of foodborne illness leading to hospital admissions in Western countries. Sources of contamination can be identified through international surveillance systems for foodborne bacteria and strains' genetic data sharing. Large-scale whole genome studies have increased our knowledge on the diversity and evolution of L. monocytogenes, while recent pathophysiological investigations have improved our mechanistic understanding of listeriosis. In this article, we present an overview of human listeriosis with particular focus on relevant features of the causative bacterium, epidemiology, risk groups, pathogenesis, clinical manifestations, and treatment and prevention.

Impact of Culture-Independent Diagnostic Testing on Recovery of Enteric Bacterial Infections

Background

Culture-independent diagnostic tests (CIDTs) are increasingly used to identify enteric pathogens. However, foodborne illness surveillance systems have relied upon culture confirmation to estimate disease burden and identify outbreaks through molecular subtyping. This study examined the impacts of CIDT and estimated costs for culture verification of Shigella, Salmonella, Shiga toxin-producing Escherichia coli (STEC), and Campylobacter at the Tennessee Department of Health Public Health Laboratory (PHL).

Methods

This observational study included laboratory and epidemiological surveillance data collected between years 2013-2016 from patients with the reported enteric illness. We calculated pathogen recovery at PHL based on initial diagnostic test type reported at the clinical laboratory. Adjusted prevalence ratios (PRs) and 95% confidence intervals (CIs) were estimated with modified Poisson regression. Estimates of cost were calculated for pathogen recovery from CIDT-positive specimens compared to recovery from culture-derived isolates.

Results

During the study period, PHL received 5553 specimens from clinical laboratories from patients with the enteric illness. Pathogen recovery was 57% (984/1713) from referred CIDT-positive stool specimens and 95% (3662/3840) from culture-derived isolates (PR, 0.61 [95% CI, .56-.66]). Pathogen recovery from CIDT-positive specimens varied based on pathogen type: Salmonella (72%), Shigella (64%), STEC (57%), and Campylobacter (26%). Compared to stool culture-derived isolates, the cost to recover pathogens from 100 CIDT-positive specimens was higher for Shigella (US $6192), Salmonella (US $18373), and STEC (US $27783).

Conclusions

Pathogen recovery was low from CIDT-positive specimens for enteric bacteria. This has important implications for the current enteric disease surveillance system, outbreak detection, and costs for public health programs.

Changing US Population Demographics: What Does This Mean for Listeriosis Incidence and Exposure?

Listeria monocytogenes is an important cause of foodborne illness hospitalization, fetal loss, and death in the United States. Listeriosis incidence rate varies significantly among population subgroups with pregnant women, older persons, and the Hispanic population having increased relative risks compared with the other subpopulations. Using estimated rates of listeriosis per subpopulation based on FoodNet data from 2004 to 2009, we evaluate the expected number of cases and incidence rates of listeriosis in the US population and the pregnant women subpopulation as the demographic composition changes over time with respect to ethnicity, pregnancy status, and age distribution. If the incidence rate per subpopulation is held constant, the overall US population listeriosis incidence rate would increase from 0.25 per 100,000 (95% confidence interval [CI]: 0.19-0.34) in 2010 to 0.28 (95% CI: 0.22-0.38) in 2020 and 0.32 (95% CI: 0.25-0.43) in 2030, because of the changes in the population structure. Similarly, the pregnancy-associated incidence rate is expected to increase from 4.0 per 100,000 pregnant women (95% CI: 2.5-6.5) in 2010 to 4.1 (95% CI: 2.6-6.7) in 2020 and 4.4 (95% CI: 2.7-7.2) in 2030 as the proportion of Hispanic pregnant women increases. We further estimate that a reduction of 12% in the exposure of the US population to L. monocytogenes would be needed to maintain a constant incidence rate from 2010 to 2020 (current trend), assuming infectivity (strain virulence distribution and individual susceptibility) is unchanged. To reduce the overall US population incidence rate by one-third (Healthy People 2020 goal) would require a reduction in exposure (or infectivity) to L. monocytogenes of 48% over the same time period. Reduction/elimination in exposure of pregnant and Hispanic subpopulations alone could not meet this target. This information may be useful in setting public health targets, developing risk management options, and in interpreting trends in the public health burden of foodborne listeriosis in the United States.

Factors associated with recovery of meat products following recalls due to Shiga toxin-producing Escherichia coli

Food-product recall data for recalls due to Shiga toxin-producing Escherichia coli (STEC) from 2000 to 2012 were obtained for establishments regulated by the United States Department of Agriculture, Food Safety and Inspection Service (FSIS). Statistical tests were used to assess the factors associated with recovery of product following STEC recalls along with the relationship between cluster detection and jurisdictions. Our results indicated that the percentage of recalled product recovered following a recall action due to STEC was dependent on the complexity of distribution, type of distribution, amount of time between production and recall dates, and the number of pounds of product recalled. Illness-related STEC recalls were associated with a lower percentage of product recovery which was probably impacted by larger amounts of product recalled, broader production scope, and delays from epidemiological and traceback investigations. Further, detection of illnesses related to STEC recalls seemed to be enhanced in states with additional resources and a history of successful foodborne investigations. This makes an argument for additional resources dedicated to public health agencies specifically for the surveillance of foodborne illnesses.

Use of Internet Search Queries to Enhance Surveillance of Foodborne Illness

“Food poisoning” queries were correlated with the number of foodborne illness–related hospital stays.

As a supplement to or extension of methods used to determine trends in foodborne illness over time, we propose the use of Internet search metrics. We compared Internet query data for foodborne illness syndrome–related search terms from the most popular 5 Korean search engines using Health Insurance Review and Assessment Service inpatient stay data for 26 International Classification of Diseases, Tenth Revision, codes for foodborne illness in South Korea during 2010–2012. We used time-series analysis with Seasonal Autoregressive Integrated Moving Average (SARIMA) models. Internet search queries for “food poisoning” correlated most strongly with foodborne illness data (r = 0.70, p<0.001); furthermore, “food poisoning” queries correlated most strongly with the total number of inpatient stays related to foodborne illness during the next month (β = 0.069, SE 0.017, p<0.001). This approach, using the SARIMA model, could be used to effectively measure trends over time to enhance surveillance of foodborne illness in South Korea.

ACG Clinical Guideline: Diagnosis, Treatment, and Prevention of Acute Diarrheal Infections in Adults

Acute diarrheal infections are a common health problem globally and among both individuals in the United States and traveling to developing world countries. Multiple modalities including antibiotic and non-antibiotic therapies have been used to address these common infections. Information on treatment, prevention, diagnostics, and the consequences of acute diarrhea infection has emerged and helps to inform clinical management. In this ACG Clinical Guideline, the authors present an evidence-based approach to diagnosis, prevention, and treatment of acute diarrhea infection in both US-based and travel settings.

Genomic Epidemiology: Whole-Genome-Sequencing-Powered Surveillance and Outbreak Investigation of Foodborne Bacterial Pathogens

As we are approaching the twentieth anniversary of PulseNet, a network of public health and regulatory laboratories that has changed the landscape of foodborne illness surveillance through molecular subtyping, public health microbiology is undergoing another transformation brought about by so-called next-generation sequencing (NGS) technologies that have made whole-genome sequencing (WGS) of foodborne bacterial pathogens a realistic and superior alternative to traditional subtyping methods. Routine, real-time, and widespread application of WGS in food safety and public health is on the horizon. Technological, operational, and policy challenges are still present and being addressed by an international and multidisciplinary community of researchers, public health practitioners, and other stakeholders.

Making One Health a Reality--Crossing Bureaucratic Boundaries

A One Health approach requires that nontraditional partners with differing mandates collaborate and communicate effectively. Barriers to such redefined relationships range from personality and institutional cultural and value differences to impediments that require changes in agency-specific policies. This article reviews interagency One Health collaborations, nationally and internationally. It presents a series of case studies that describe situations in which barriers were overcome, thus culminating in successful One Health outcomes. The case studies illustrate challenges, tipping points, and externally enabling factors that help institutionalize cross-bureaucratic working relationships. Likewise, the cases demonstrate the added value of taking a One Health approach to solving (or preventing) public health problems.

Lactic Acid Bacteria as a Surface Display Platform for Antigens

<b><i>Background:</i></b> Food poisoning and diarrheal diseases continue to pose serious health care and socioeconomic problems worldwide. <i>Campylobacter</i> spp. is a very widespread cause of gastroenteritis. Over the past decade there has been increasing interest in the use of lactic acid bacteria (LAB) as mucosal delivery vehicles. They represent an attractive opportunity for vaccination in addition to vaccination with attenuated bacterial pathogens. <b><i>Methods:</i></b> We examined the binding ability of hybrid proteins to nontreated or trichloroacetic acid (TCA)-pretreated LAB cells by immunofluorescence and Western blot analysis. <b><i>Results:</i></b> In this study we evaluated the possibility of using GEM (Gram-positive enhancer matrix) particles of <i>Lactobacillus salivarius</i> as a binding platform for 2 conserved, immunodominant, extracytoplasmic <i>Campylobacter jejuni</i> proteins: CjaA and CjaD. We analyzed the binding ability of recombinant proteins that contain <i>C. jejuni</i> antigens (CjaA or CjaD) fused with the protein anchor (PA) of the <i>L. lactis </i>peptidoglycan hydrolase AcmA, which comprises 3 LysM motifs and determines noncovalent binding to the cell wall peptidoglycan. Both fused proteins, i.e. 6HisxCjaAx3LysM and 6HisxCjaDx3LysM, were able to bind to nontreated or TCA-pretreated <i>L. salivarius</i> cells. <b><i>Conclusion:</i></b> Our results documented that the LysM-mediated binding system allows us to construct GEM particles that present 2 <i>C. jejuni</i> antigens.

Multi-laboratory evaluation of the rapid genoserotyping array (SGSA) for the identification of Salmonella serovars

Salmonella serotyping is an essential first step for identification of isolates associated with disease outbreaks. The Salmonella genoserotyping array (SGSA) is a microarray-based alternative to standard serotyping designed to rapidly identify 57 of the most commonly reported serovars through detection of the genes encoding surface O and H antigens and reporting the corresponding serovar in accordance with the existing White-Kaufmann-Le Minor serotyping scheme. In this study, we evaluated the SGSA at 4 laboratories in 3 countries by testing 1874 isolates from human and non-human sources. The SGSA correctly identified 96.7% of isolates from the target 57 serovars. For the prevalent and clinically important Salmonella serovars Enteritidis and Typhimurium, test specificity and sensitivity were greater than 98% and 99%, respectively. Due to its high-throughput nature, the SGSA is a rapid and cost-effective alternative to standard serotyping for identifying the most prevalent serovars of Salmonella.

A capsule conjugate vaccine approach to prevent diarrheal disease caused by Campylobacter jejuni

Campylobacter jejuni is a major cause of diarrheal disease and results in high levels of morbidity and economic loss in both industrialized and developing regions of the world. To date, prior vaccine approaches have failed to confer protection against this enteric pathogen. Key challenges to the development of a practical Campylobacter vaccine for human use include a lack of understanding of Campylobacter pathogenesis and well-defined immune correlates of protection. With the discovery that C. jejuni expresses a capsule polysaccharide associated with virulence, a conjugate vaccine approach is currently being evaluated. Conjugate vaccines have been successfully developed and implemented against other invasive mucosal pathogens including Streptococcus pneumoniae, Neisseria meningitidis, and Hemophilus influenzae. Furthermore, Shigella-based conjugate vaccines based on lipopolysaccharide have shown promising results in field trials. A prototype C. jejuni conjugate vaccine is currently entering human testing.

Invasive listeriosis in the Foodborne Diseases Active Surveillance Network (FoodNet), 2004-2009: further targeted prevention needed for higher-risk groups

BACKGROUND

Listeriosis can cause severe disease, especially in fetuses, neonates, older adults, and persons with certain immunocompromising and chronic conditions. We summarize US population-based surveillance data for invasive listeriosis from 2004 through 2009.

METHODS

We analyzed Foodborne Diseases Active Surveillance Network (FoodNet) data for patients with Listeria monocytogenes isolated from normally sterile sites. We describe the epidemiology of listeriosis, estimate overall and specific incidence rates, and compare pregnancy-associated and nonpregnancy-associated listeriosis by age and ethnicity.

RESULTS

A total of 762 listeriosis cases were identified during the 6-year reporting period, including 126 pregnancy-associated cases (17%), 234 nonpregnancy-associated cases(31%) in patients aged <65 years, and 400 nonpregnancy-associated cases (53%) in patients aged ≥ 65 years. Eighteen percent of all cases were fatal. Meningitis was diagnosed in 44% of neonates. For 2004-2009, the overall annual incidence of listeriosis varied from 0.25 to 0.32 cases per 100,000 population. Among Hispanic women, the crude incidence of pregnancy-associated listeriosis increased from 5.09 to 12.37 cases per 100,000 for the periods of 2004-2006 and 2007-2009, respectively; among non-Hispanic women, pregnancy-associated listeriosis increased from 1.74 to 2.80 cases per 100,000 for the same periods. Incidence rates of nonpregnancy-associated listeriosis in patients aged ≥ 65 years were 4-5 times greater than overall rates annually.

CONCLUSIONS

Overall listeriosis incidence did not change significantly from 2004 through 2009. Further targeted prevention is needed, including food safety education and messaging (eg, avoiding Mexican-style cheese during pregnancy). Effective prevention among pregnant women, especially Hispanics, and older adults would substantially affect overall rates.

Characteristics of foodborne disease outbreak investigations conducted by Foodborne Diseases Active Surveillance Network (FoodNet) sites, 2003-2008

BACKGROUND

A mean of ≥ 1000 foodborne disease outbreaks (FBDOs) causing ≥ 20,000 illnesses are reported to the Centers for Disease Control and Prevention (CDC) annually. We evaluated characteristics of successful outbreak investigations (ie, those that identified an etiologic agent or food vehicle) in the Foodborne Diseases Active Surveillance Network (FoodNet).

METHODS

FBDOs were defined as the occurrence of ≥ 2 cases of a similar illness resulting from ingestion of a common food. FBDOs reported to CDC Foodborne Disease Outbreak Surveillance System during 2003-2008 with FoodNet supplemental data available were included in the analyses.

RESULTS

Data regarding 1200 FBDOs were available. An etiologic agent was confirmed in 715 (60%); a food vehicle was identified in 387 (32%). At least 4 fecal specimens were collected in 425 of 639 outbreaks (67%) with a confirmed etiologic agent and 48 of 232 (21%) without a confirmed etiologic agent (odds ratio [OR], 7.6; 95% confidence interval [CI], 5.3-10.9). A food vehicle was identified in 314 (47%) of 671 outbreaks investigated using a case-control or cohort study, compared with only 73 (14%) of 529 outbreaks investigated by using other methods (OR, 5.5; 95% CI, 4.1-7.3). At least 1 barrier affecting the success of the investigation was reported for 655 outbreaks, including too few patients (n = 172; 26%), too few stool specimens (n = 167; 25%), and too few control subjects (n = 152; 23%).

CONCLUSIONS

Etiologic agent and vehicle are frequently undetermined in FBDOs. Greater emphasis on fecal specimen collection and overcoming barriers to pursuing analytic epidemiologic studies can improve ascertainment of these factors.

Visual analytics of surveillance data on foodborne vibriosis, United States, 1973-2010

Foodborne illnesses caused by microbial and chemical contaminants in food are a substantial health burden worldwide. In 2007, human vibriosis (non-cholera Vibrio infections) became a notifiable disease in the United States. In addition, Vibrio species are among the 31 major known pathogens transmitted through food in the United States. Diverse surveillance systems for foodborne pathogens also track outbreaks, illnesses, hospitalization and deaths due to non-cholera vibrios. Considering the recognition of vibriosis as a notifiable disease in the United States and the availability of diverse surveillance systems, there is a need for the development of easily deployed visualization and analysis approaches that can combine diverse data sources in an interactive manner. Current efforts to address this need are still limited. Visual analytics is an iterative process conducted via visual interfaces that involves collecting information, data preprocessing, knowledge representation, interaction, and decision making. We have utilized public domain outbreak and surveillance data sources covering 1973 to 2010, as well as visual analytics software to demonstrate integrated and interactive visualizations of data on foodborne outbreaks and surveillance of Vibrio species. Through the data visualization, we were able to identify unique patterns and/or novel relationships within and across datasets regarding (i) causative agent; (ii) foodborne outbreaks and illness per state; (iii) location of infection; (iv) vehicle (food) of infection; (v) anatomical site of isolation of Vibrio species; (vi) patients and complications of vibriosis; (vii) incidence of laboratory-confirmed vibriosis and V. parahaemolyticus outbreaks. The additional use of emerging visual analytics approaches for interaction with data on vibriosis, including non-foodborne related disease, can guide disease control and prevention as well as ongoing outbreak investigations.

Prevention and treatment of viral diarrhea in pediatrics

Diarrhea is the second largest cause of mortality worldwide in children from the perinatal period to the age of 5 years. Rotavirus has been the most commonly identified viral cause of diarrhea in children. Norovirus is now recognized as the second most common viral pathogen. Adenovirus, astrovirus and sapovirus are the other major viral causes of pediatric gastroenteritis. Strategies for prevention include basic hygiene, optimization of nutrition and, ultimately, vaccination. Two new vaccines have recently been licensed for the prevention of rotavirus, the monovalent human rotavirus vaccine (Rotarix) and the pentavalent bovine-human reassortant vaccine (RotaTeq). These vaccines have already dramatically decreased the morbidity associated with rotavirus in countries where they are widely used. Efforts to develop a norovirus vaccine face substantial hurdles. Treatment of the viral pathogens is primarily limited to symptomatic measures.

Integrated approaches for the public health prioritization of foodborne and zoonotic pathogens

To address the persistent problems of foodborne and zoonotic disease, public health officials worldwide face difficult choices about how to best allocate limited resources and target interventions to reduce morbidity and mortality. Data-driven approaches to informing these decisions have been developed in a number of countries. Integrated comparative frameworks generally share three methodological components: estimating incidence of acute illnesses, chronic sequelae, and mortality; attributing pathogen-specific illnesses to foods; and calculating integrated measures of disease burden such as cost of illness, willingness to pay, and health-adjusted life years (HALYs). To discuss the similarities and differences in these approaches, to seek consensus on principles, and to improve international collaboration, the E.U. MED-VET-NET and the U.S.-based Food Safety Research Consortium organized an international conference convened in Berlin, Germany, on July 19-21, 2006. This article draws in part on the deliberations of the conference and discusses general principles, data needs, methodological issues and challenges, and future research needs pertinent to objective data-driven analyses and their potential use for priority setting of foodborne and zoonotic pathogens in public health policy.

Phenotype MicroArray in the metabolic characterisation of Salmonella serotypes Agona, Enteritidis, Give, Hvittingfoss, Infantis, Newport and Typhimurium

The Phenotype MicroArray (PM) technology was used to study the metabolic characteristics of 29 Salmonella strains belonging to seven serotypes of S. enterica spp. enterica. Strains of serotypes Typhimurium (six strains among definite phage types DTs 1, 40 and 104) and Agona (two strains) were tested for 949 substrates, Enteritidis (six strains of phage type PT1), Give, Hvittingfoss, Infantis and Newport strains (two of each) were tested for 190 substrates and seven other Agona strains for 95 substrates. The strains represented 18 genotypes in pulsed-field gel electrophoresis (PFGE). Among 949 substrates, 18 were identified that could be used to differentiate between the strains of those seven serotypes or within a single serotype. Unique metabolic differences between the Finnish endemic Typhimurium DT1 and Agona strains were detected, for example, in the metabolism of D-tagatose, D-galactonic acid gamma-lactone and L-proline as a carbon source. Thus, the PM technique is a useful tool for identifying potential differential markers on a metabolic basis that could be used for epidemiological surveillance.

Prevalence and antimicrobial resistance of Salmonella serovars in conventional and organic chickens from Louisiana retail stores

In this 1-year survey from October 2006 to September 2007, we isolated and characterized 126 Salmonella isolates from conventionally raised (n=141) and organically raised (n=53) chicken carcasses obtained from 27 retail stores in Baton Rouge, Louisiana. Salmonella was isolated from 22% of conventional and from 20.8% of organic chicken samples. Eight Salmonella serovars were identified; predominant ones included Kentucky, Hadar, and Enteritidis. The vast majority of isolates within the same chicken sample possessed the same pulsed-field gel pattern. All Salmonella isolates were susceptible to amikacin, ceftriaxone, and ciprofloxacin; however, decreased susceptibility to quinolones (7.1%) or extended-spectrum cephalosporins (45.2%) was observed. Resistance to multiple antimicrobials (two or more) was found among 52.4% of the Salmonella isolates. Antimicrobial resistance profiles differed greatly among Salmonella serovars and also depended on the type of chicken from which they were recovered. Salmonella Kentucky isolates from organic chicken samples were susceptible to 11 of the antimicrobials tested, whereas those from conventional chickens were only susceptible to 4 antimicrobials. Three Salmonella Kentucky isolates from conventional chickens possessed multidrug resistance phenotype MDR-AmpC. Results of this study provide baseline data on both prevalence and antimicrobial resistance of Salmonella in retail chickens in this region and emphasize the need for implementing effective control measures to reduce Salmonella contamination and the levels of antimicrobial-resistant Salmonella in both conventionally and organically raised poultry products. Further studies involving larger sample sizes over time are needed to better monitor and assess the trend of prevalence and antimicrobial susceptibility among Salmonella serovars in retail chickens.

The economics of enteric infections: human foodborne disease costs

The World Health Organization estimates that in 2005, 1.5 million people died, worldwide, from diarrheal diseases. A separate study estimated that 70% of diarrheal diseases are foodborne. The widely cited US estimate is that there are 76 million foodborne illnesses annually, resulting in 325,000 hospitalizations and 5200 deaths. However, there are epidemiologic and methodologic challenges to accurately estimate the economic burden of foodborne disease on society, either in terms of monetary costs or non-monetary units of measurement. Studies on the economic burden of foodborne disease vary considerably: some analyze the effects of a single pathogen or a single outbreak, whereas others attempt to estimate all foodborne disease in a country. Differences in surveillance systems, methodology, and other factors preclude meaningful comparisons across existing studies. However, if it were possible to completely estimate the societal costs for all acute foodborne diseases and their chronic sequelae worldwide, on the basis of currently available data, worldwide costs from these illnesses would be substantial. Moreover, foodborne infections are largely manifested as intestinal illnesses and are largely preventable. Total costs of foodborne disease would be much smaller in the United States and the world if economic incentives for industry to produce safer food were improved. However, costs of implementing new food safety prevention and control rules must be weighed against the estimated benefits of reducing foodborne disease to determine net benefits so that governments have information to efficiently allocate funds among competing programs.

An ecological analysis of sociodemographic factors associated with the incidence of salmonellosis, shigellosis, and E. coli O157:H7 infections in US counties

Identifying county-level sociodemographic and economic factors associated with the incidence of enteric disease may provide new insights concerning the dynamics of community transmission of these diseases as well as opportunities for prevention. We used data from the National Notifiable Diseases Surveillance System, the U.S. Census Bureau, and the Health Resources and Services Administration to conduct an ecological analysis of 26 sociodemographic and economic factors associated with the incidence of salmonellosis, shigellosis, and E. coli O157:H7 infections in US counties for the period 1993 to 2002. Our study indicates that race, ethnicity, place of residence, age, educational attainment, and poverty may affect the risk of acquiring one of these enteric bacterial diseases. The lack of specificity of information regarding salmonellae and shigellae serotypes may have led to less specific associations between community-level determinants and reported incidence of those diseases. Future ecological analyses should use serotype-specific data on incidence, which may be available from laboratory-based surveillance systems.

Different feed withdrawal times before slaughter influence caecal fermentation and faecal Salmonella shedding in pigs

The effects of different pre-slaughter feed withdrawal times (FWT) on the gastrointestinal tract (GIT) weight and the gut environment of pigs and Salmonella shedding were investigated. Trial 1 evaluated the effects under experimental conditions (feed withdrawal for 18, 30 and 36 h) and trial 2 under commercial conditions (15 and 30 h). In trial 1, the GIT weight tended to decrease (P=0.07), the caecal pH increased (P<0.0001), short-chain fatty acids (SCFA) decreased (P<0.001) and percentage of branched-chain fatty acids (BCFA) increased as FWT increased. Similar results were observed in trial 2, but Enterobacteriaceae numbers and Salmonella positive pigs tended to increase whereas lactobacilli decreased (P<0.0005) as FWT increased. The increase in FWT involved changes in the gut microbial ecosystem that could be associated with the trend of increased caecal Enterobacteriaceae and Salmonella in faeces, and may represent a higher risk of carcass contamination in cases of laceration of viscera.

Emergency care physicians' knowledge, attitudes, and practices related to surveillance for foodborne disease in the United States

During the past decade, the incidence of certain bacterial pathogens that are commonly transmitted through food in the United States has decreased. Concurrently, the emergency department has become an increasingly common setting for health care. Because public health surveillance for bacterial foodborne diseases fundamentally depends on stool cultures, we conducted a survey of physicians who attended an emergency medicine conference to describe knowledge, attitudes, and practices among this provider population. A convenience sample of 162 physicians, representing 34 states, provided responses. Thirty-eight percent reported having ordered a stool culture for the most recent patient with acute diarrheal illness examined in the emergency department, but only 26% of the physicians subsequently received the stool culture results. For only 2 pathogens (Escherichia coli O157:H7 and Salmonella species) did at least one-half of the respondents provide the correct response regarding whether selected diarrheal disease pathogens were reportable in their state. Responses indicated familiarity with the Infectious Diseases Society of America's practice guidelines regarding stool cultures for patients with severe symptoms and a history of travel, but less so with characteristics of public health importance (i.e., attendance at day care and employment as a restaurant cook). We recommend that educational opportunities be made available to emergency care physicians that highlight the public health significance of acute diarrheal illness and that reinforce guidelines regarding culturing stool specimens, making recommendations to prevent further transmission, and reporting to local health authorities.

Foodborne illness

While few patients with foodborne illness present with life-threatening symptoms, there are a number of foodborne infectious diseases and toxins that the emergency physician or other health care provider must consider in the evaluation of these patients. Given the frequency of international travel, as well as the risk associated with recurrent outbreaks of foodborne illness from commercial food sources, it is important to recognize various syndromes of foodborne illness, including those which may require specific evaluation and management strategies. This article reviews a number of the most common causes of foodborne illness, as well as several less common pathogens with the potential for causing significant morbidity and mortality if not promptly identified and treated.