Infectious diarrhea: when to test and when to treat

Accuracy of Telehealth Visits for Acute Care Needs in Family Medicine

Introduction As primary care practices transition to a post-pandemic system of healthcare, it is important to recognize the benefits of offering telehealth services. Little research is available on the effectiveness of telehealth visits for managing acute illnesses or conditions in primary care practice. Methods Using the reporting functionality in the Epic™ electronic health record (EHR) (Epic Systems Corporation, Verona), a report was generated to identify all telehealth visit encounters that were completed in a family medicine clinic from March 1, 2020, to June 30, 2020. The report identified patients who had an acute complaint and required an in-office visit within 60 days of the telehealth encounter. If the patient required a face-to-face visit, that was not directed by the provider, the chart was reviewed to determine whether the diagnosis changed. The primary outcome was returning for a face-to-face visit within 30 days of the telehealth visit for the same acute need. Results The cohort included 349 telehealth visits for 303 patients. For patients who had more than one telehealth visit, only the first one was included in the analysis. Among the 303 patients, 50 (16.5%) returned for a face-to-face visit within 30 days of the telehealth visit (95% confidence interval: 12.5%-21.2%), and 71 (23.6%) returned for a telehealth visit within 60 days (95% confidence interval: 18.9%-28.8%). Furthermore, 19 of the 50 patients (38%) that returned for a face-to-face visit did not have a change in diagnosis, and, in some instances, the diagnosis made on the telehealth visit was only slightly different from the face-to-face visit. Discussion and conclusion Telehealth, specifically two-way, synchronous, interactive patient-provider communication through audio and video equipment, for acute care needs in a primary care practice helps reduce the need for in-person visits and can address patient complaints without the need for in-person follow-up.

Combatting infectious diarrhea: innovations in treatment and vaccination strategies

INTRODUCTION

The escalating prevalence of infectious diseases is an important cause of concern in society. Particularly in several developing countries, infectious diarrhea poses a major problem, with a high fatality rate, especially among young children. The condition is divided into four classes, namely, acute diarrhea, invasive diarrhea, acute bloody diarrhea, and chronic diarrhea. Various pathogenic agents, such as bacteria, viruses, protozoans, and helminths, contribute to the onset of this condition.

AREAS COVERED

The review discusses the scenario of infectious diarrhea, the prevalent types, as well as approaches to management including preventive, therapeutic, and vaccination strategies. The vaccination techniques are extensively discussed including the available vaccines, their advantages as well as limitations.

EXPERT OPINION

There are several approaches available to develop new-improved vaccines. In addition, route of immunization is important and aerosols/nasal sprays, oral route, skin patches, powders, and liquid jets to minimize needles can be used. Plant-based vaccines, such as rice, might save packing and refrigeration costs by being long-lasting, non-refrigerable, and immunogenic. Future research should utilize predetermined PCR testing intervals and symptom monitoring to identify persistent pathogens after therapy and symptom remission.

Bacteriophages for the Targeted Control of Foodborne Pathogens

Foodborne illness is exacerbated by novel and emerging pathotypes, persistent contamination, antimicrobial resistance, an ever-changing environment, and the complexity of food production systems. Sporadic and outbreak events of common foodborne pathogens like Shiga toxigenic E. coli (STEC), Salmonella, Campylobacter, and Listeria monocytogenes are increasingly identified. Methods of controlling human infections linked with food products are essential to improve food safety and public health and to avoid economic losses associated with contaminated food product recalls and litigations. Bacteriophages (phages) are an attractive additional weapon in the ongoing search for preventative measures to improve food safety and public health. However, like all other antimicrobial interventions that are being employed in food production systems, phages are not a panacea to all food safety challenges. Therefore, while phage-based biocontrol can be promising in combating foodborne pathogens, their antibacterial spectrum is generally narrower than most antibiotics. The emergence of phage-insensitive single-cell variants and the formulation of effective cocktails are some of the challenges faced by phage-based biocontrol methods. This review examines phage-based applications at critical control points in food production systems with an emphasis on when and where they can be successfully applied at production and processing levels. Shortcomings associated with phage-based control measures are outlined together with strategies that can be applied to improve phage utility for current and future applications in food safety.

Derivation and External Validation of a Clinical Prediction Model for Viral Diarrhea Etiology in Bangladesh

Background

Antibiotics are commonly overused for diarrheal illness in many low- and middle-income countries, partly due to a lack of diagnostics to identify viral cases, in which antibiotics are not beneficial. This study aimed to develop clinical prediction models to predict risk of viral-only diarrhea across all ages, using routinely collected demographic and clinical variables.

Methods

We used a derivation dataset from 10 hospitals across Bangladesh and a separate validation dataset from the icddr,b Dhaka Hospital. The primary outcome was viral-only etiology determined by stool quantitative polymerase chain reaction. Multivariable logistic regression models were fit and externally validated; discrimination was quantified using area under the receiver operating characteristic curve (AUC) and calibration assessed using calibration plots.

Results

Viral-only diarrhea was common in all age groups (<1 year, 41.4%; 18-55 years, 17.7%). A forward stepwise model had AUC of 0.82 (95% confidence interval [CI], .80-.84) while a simplified model with age, abdominal pain, and bloody stool had AUC of 0.81 (95% CI, .78-.82). In external validation, the models performed adequately although less robustly (AUC, 0.72 [95% CI, .70-.74]).

Conclusions

Prediction models consisting of 3 routinely collected variables can accurately predict viral-only diarrhea in patients of all ages in Bangladesh and may help support efforts to reduce inappropriate antibiotic use.

An allergist's approach to food poisoning

Foodborne illnesses represent a significant global health concern. These preventable diseases lead to substantial mortality and morbidity worldwide. Substantial overlap with food allergy exists with similar clinical presentations and symptom onset. Knowledge of the typically implicated microorganisms and toxins can help properly identify these diseases. A thorough history is essential to differentiate between these 2 disorders. The types of food implicated may be similar including milk, egg, fish, and shellfish. The timing of symptom onset may overlap and lead to misdiagnosis of disorders such as food protein-induced enterocolitis syndrome. Classically, histamine-related food poisoning is also typically confused with true food allergy and may be seen as related to fish and cheese. Knowledge of epidemiology, patterns, and etiology of allergic conditions and foodborne illness may help the allergist differentiate among these common diseases.

Antimicrobial Properties of Chitosan and Chitosan Derivatives in the Treatment of Enteric Infections

Antibiotics played an important role in controlling the development of enteric infection. However, the emergence of antibiotic resistance and gut dysbiosis led to a growing interest in the use of natural antimicrobial agents as alternatives for therapy and disinfection. Chitosan is a nontoxic natural antimicrobial polymer and is approved by GRAS (Generally Recognized as Safe by the United States Food and Drug Administration). Chitosan and chitosan derivatives can kill microbes by neutralizing negative charges on the microbial surface. Besides, chemical modifications give chitosan derivatives better water solubility and antimicrobial property. This review gives an overview of the preparation of chitosan, its derivatives, and the conjugates with other polymers and nanoparticles with better antimicrobial properties, explains the direct and indirect mechanisms of action of chitosan, and summarizes current treatment for enteric infections as well as the role of chitosan and chitosan derivatives in the antimicrobial agents in enteric infections. Finally, we suggested future directions for further research to improve the treatment of enteric infections and to develop more useful chitosan derivatives and conjugates.

An analysis of antibiotic prescribing practices for enteric bacterial infections within FoodNet Canada sentinel sites

OBJECTIVES

Understanding the current state of antibiotic treatment guidelines and prescribing practices for bacterial enteric infections is critical to inform antibiotic stewardship initiatives. This study aims to add to the current understanding through three objectives: (i) to identify and summarize published treatment guidelines for bacterial enteric infections; (ii) to describe observed antibiotic prescribing practices for bacterial enteric infections across three sentinel sites in Canada; and (iii) to assess concordance between observed antibiotic prescribing and treatment guidelines.

METHODS

An environmental scan of treatment guidelines for bacterial enteric infections was conducted and recommendations were collated. A descriptive analysis of cases of bacterial enteric illnesses captured in FoodNet Canada's sentinel site surveillance system between 2010 and 2018 was performed. Antibiotic-use data were self-reported by cases via an enhanced questionnaire.

RESULTS

Ten treatment guidelines were identified in the environmental scan. There was substantial variation between guidelines for both when to prescribe antibiotics and which antibiotics were recommended. Of the 5877 cases of laboratory-confirmed bacterial enteric illness in the three sites, 49% of cases reported having received an antibiotic prescription. Of particular significance was the finding that 21% of verotoxigenic Escherichia coli cases received a prescription. Of the 17 antibiotics recommended in the guidelines, 14 were used in practice. In addition to these, 18 other antibiotics not included in any of the guidelines reviewed were also prescribed.

CONCLUSIONS

Our study suggests that a substantial proportion of enteric bacterial infections in Canada are prescribed antibiotics. These findings highlight the need to standardize treatment guidelines for enteric illnesses and could be used to inform future stewardship programme development.

Multidrug-resistant enteric pathogens in older children and adults with diarrhea in Bangladesh: epidemiology and risk factors

BACKGROUND

Antimicrobial resistance (AMR) is a global public health threat and is increasingly prevalent among enteric pathogens in low- and middle-income countries (LMICs). However, the burden of multidrug-resistant organisms (MDROs) in older children, adults, and elderly patients with acute diarrhea in LMICs is poorly understood. This study's aim was to characterize the prevalence of MDR enteric pathogens isolated from patients with acute diarrhea in Dhaka, Bangladesh, and assess a wide range of risk factors associated with MDR.

METHODS

This study was a secondary analysis of data collected from children over 5 years, adults, and elderly patients with acute diarrhea at the International Centre for Diarrhoeal Disease Research, Bangladesh Dhaka Hospital between March 2019 and March 2020. Clinical, historical, socio-environmental information, and a stool sample for culture and antimicrobial susceptibility testing were collected from each patient. Univariate statistics and multiple logistic regression were used to assess the prevalence of MDR among enteric pathogens and the association between independent variables and presence of MRDOs among culture-positive patients.

RESULTS

A total of 1198 patients had pathogens isolated by stool culture with antimicrobial susceptibility results. Among culture-positive patients, the prevalence of MDR was 54.3%. The prevalence of MDR was highest in Aeromonas spp. (81.5%), followed by Campylobacter spp. (72.1%), Vibrio cholerae (28.1%), Shigella spp. (26.2%), and Salmonella spp. (5.2%). Factors associated with having MDRO in multiple logistic regression included longer transport time to hospital (>90 min), greater stool frequency, prior antibiotic use prior to hospital presentation, and non-flush toilet use. However, pseudo-R2 was low 0.086, indicating that other unmeasured variables need to be considered to build a more robust predictive model of MDR.

CONCLUSIONS

MDR enteric pathogens were common in this study population with clinical, historical, and socio-environmental risk factors associated with MDROs. These findings may help guide clinical decision-making regarding antibiotic use and selection in patients at greatest risk of complications due to MDROs. Further prospective research is urgently needed to determine what additional factors place patients at greatest risk of MDRO, and the best strategies to mitigate the spread of MDR in enteric pathogens.

Molecular Epidemiology of Enteroaggregative Escherichia coli (EAEC) Isolates of Hospitalized Children from Bolivia Reveal High Heterogeneity and Multidrug-Resistance

Enteroaggregative Escherichia coli (EAEC) is an emerging pathogen frequently associated with acute diarrhea in children and travelers to endemic regions. EAEC was found the most prevalent bacterial diarrheal pathogen from hospitalized Bolivian children less than five years of age with acute diarrhea from 2007 to 2010. Here, we further characterized the epidemiology of EAEC infection, virulence genes, and antimicrobial susceptibility of EAEC isolated from 414 diarrheal and 74 non-diarrheal cases. EAEC isolates were collected and subjected to a PCR-based virulence gene screening of seven virulence genes and a phenotypic resistance test to nine different antimicrobials. Our results showed that atypical EAEC (a-EAEC, AggR-negative) was significantly associated with diarrhea (OR, 1.62, 95% CI, 1.25 to 2.09, p < 0.001) in contrast to typical EAEC (t-EAEC, AggR-positive). EAEC infection was most prevalent among children between 7–12 months of age. The number of cases exhibited a biannual cycle with a major peak during the transition from warm to cold (April–June). Both typical and a-EAEC infections were graded as equally severe; however, t-EAEC harbored more virulence genes. aap, irp2 and pic were the most prevalent genes. Surprisingly, we detected 60% and 52.6% of multidrug resistance (MDR) EAEC among diarrheal and non-diarrheal cases. Resistance to ampicillin, sulfonamides, and tetracyclines was most common, being the corresponding antibiotics, the ones that are frequently used in Bolivia. Our work is the first study that provides comprehensive information on the high heterogenicity of virulence genes in t-EAEC and a- EAEC and the large prevalence of MDR EAEC in Bolivia.

Use of BioFire FilmArray gastrointestinal PCR panel associated with reductions in antibiotic use, time to optimal antibiotics, and length of stay

BACKGROUND

Rapid and accurate diagnostic tools are needed for appropriate management of infectious diarrhea.

METHODS

We evaluated the impact of the introduction of rapid multiplex PCR testing using the FilmArray gastrointestinal (GI) panel (BioFire Diagnostics, LLC, Salt Lake City, UT) at our institution, and compared the results to those of standard stool cultures.

RESULTS

The most common pathogens detected by the FilmArray GI panel were Clostridium difficile (55.0%), Campylobacter species (20.9%), Salmonella species (12.4%), and Shigella/EIEC species (12.4%). Rates of reproducibility in stool culture for these pathogens ranged from 56.3 to 77.8%. Co-detection of two or more organisms was common (24.2%), most commonly involving EPEC, EAEC, ETEC, and STEC. The time from arrival in the Emergency Department to discharge or admission to the hospital was unchanged after the introduction of FilmArray GI panel, but length of hospital stay was shorter (3 vs. 7.5 days, p = 0.0002) for the FilmArray group. The time to empiric antibiotics did not differ significantly, but optimal antibiotics were started earlier after introduction of the FilmArray GI panel (hospital day 1 vs. 2, p < 0.0001). More patients were discharged without antibiotics after introduction of the FilmArray GI panel (14.0% vs. 4.5%; p < 0.001).

CONCLUSION

Our results demonstrate that the FilmArray GI panel is an important tool for improving both patient care and antibiotic stewardship, despite the tendency for positive results with multiple pathogens.

Glucose sensitizes the stationary and persistent population of Vibrio cholerae to ciprofloxacin

The subject of analysis in this report was the antibiotic susceptibility of V. cholerae under glucose supplementation since the metabolites can significantly alter the antibiotic sensitivity of bacteria. Glucose could change the antibiotic susceptibility in a growth phase-dependent manner, however, the antibiotic susceptibility of exponentially growing cells was not affected in the presence of glucose. What has been shown is that the stationary phase cells which show higher antibiotic tolerance, could be sensitized to ciprofloxacin and ampicillin by glucose supplementation (tenfold sensitive). The glucose increases the respiration which in turn increases the metabolism and cell division rate. Furthermore, the addition of glucose could increase the susceptibility of persister cells to ciprofloxacin only. In general, the bacterial susceptibility can be increased by combining the antibiotics with glucose.

Evaluation of the Vibrant DNA microarray for the high-throughput multiplex detection of enteric pathogens in clinical samples

Background

Rapid detection of a wide range of etiologic agents is essential for appropriate treatment and control of gastrointestinal (GI) infections. A variety of microbial species including bacteria, viruses, parasites, and fungi have been recognized as diarrheagenic enteric pathogens. However, multiplex testing of various targets in a single reaction needs further improvement because of its limitation in species and throughput.

Results

This study aims at developing and evaluating a DNA microarray-based qualitative multiplexed polymerase chain reaction (PCR) assay, Vibrant GI pathogen panel (GPP), for simultaneous detection of 27 enteric GI pathogenic targets (16 bacteria, 5 viruses, 4 parasites, and 2 fungi) directly from stool specimens. Limits of detection ranged from 10² to 10⁴ cells/mL for bacteria, 10² to 10³ cells/mL for parasites, 10² to 10³ RNA copies/mL for viruses, and 10² to 10³ cells/mL for fungi. Performance characteristics were determined using 27 Quantitative Genomic DNAs, 212 spiked stool specimens, 1067 clinical and archived stool specimens. Overall sensitivity was 95.9% (95% CI 92.4–98.1) and specificity was 100% (95% CI 99.9–100). Polymicrobial detections contained either two or three organisms was 20.2% (35/173) of positive clinical specimens and 3.3% (35/1055) of all clinical specimens.

Conclusion

The Vibrant GPP is a comprehensive, high-throughput, and rapid DNA microarray to provide etiologic diagnosis of GI infections in the laboratory setting.

Performance of Stool-testing Recommendations for Acute Gastroenteritis When Used to Identify Children With 9 Potential Bacterial Enteropathogens

BACKGROUND

The ability to identify bacterial pathogens that necessitate specific clinical management or public health action in children with acute gastroenteritis is crucial to patient care and public health. However, existing stool-testing guidelines offer inconsistent recommendations, and their performance characteristics are unknown. We evaluated 6 leading gastroenteritis guidelines (eg, those of the Centers for Disease Control and Prevention and Infectious Disease Society of America) that recommend when to test children's stool for bacterial enteropathogens.

METHODS

Via 2 emergency departments in Alberta, Canada, we enrolled 2447 children <18 years old who presented with ≥3 episodes of diarrhea and/or vomiting in a 24-hour period. All participants were tested for 9 bacterial enteropathogens: Aeromonas, Campylobacter, Escherichia coli O157, other Shiga toxin-producing E. coli, enterotoxigenic E. coli, Salmonella, Shigella, Vibrio, and Yersinia. Patient data gathered at the index visit were used to determine whether guidelines would recommend testing. Sensitivity and specificity to recommend testing for children with bacterial enteropathogens were calculated for each guideline.

RESULTS

Outcome data were available for 2391 (97.7%) participants, and 6% (144/2391) of participants tested positive for a bacterial enteropathogen. Guideline sensitivity ranged from 25.8% (95% confidence interval [CI] 18.7-33.0%) to 66.9% (95% CI 59.3-74.6%), and varied for individual pathogens. Guideline specificity for all bacterial enteropathogens ranged from 63.6% (95% CI 61.6-65.6%) to 96.5% (95% CI 95.7-97.2%).

CONCLUSIONS

No guideline provided optimally balanced performance. The most sensitive guidelines missed one-third of cases and would drastically increase testing volumes. The most specific guidelines missed almost 75% of cases.

The independent risk factors of early diarrhoea in enteral nutrition for ICU patients

Objective

To investigate the prevalence of and factors associated with diarrhoea in the early stage of enteral nutrition in critically ill patients in intensive care units (ICUs).

Methods

This prospective, multicentre, observational study enrolled consecutive patients who were newly admitted to ICUs and received enteral nutrition treatment. Events were observed continuously for 7 days or until patients were transferred out of the ICU after enteral nutrition. Demographic and clinical data, enteral nutrition data, diarrhoea-related data and outcomes were recorded. A multivariate logistic regression analysis was used to analyse the risk factors for diarrhoea.

Results

The study included 533 patients, of whom 164 (30.8%) developed diarrhoea. Diarrhoea was most commonly observed on the first to third days after starting enteral nutrition treatment. The median (interquartile range) duration of diarrhoea was 2 (1–3) days. The administration of gastrointestinal prokinetic agents, the increase in acute physiological and chronic health scores and the pyloric posterior feeding method were independent risk factors for diarrhoea.

Conclusion

The increased severity of illness, the administration of gastrointestinal prokinetic agents and the pyloric posterior feeding method were independent risk factors for diarrhoea in critically ill ICU patients undergoing enteral nutrition treatment.

Evaluation of the BioFire FilmArray Gastrointestinal Panel and Real-Time Polymerase Chain Reaction Assays for the Detection of Major Diarrheagenic Pathogens by a Multicenter Diarrheal Disease Surveillance Program in China

In the field of the detection of pathogens responsible for infectious diarrhea, multiplex nucleic acids detection technology has attracted attention due to its ability to simultaneously screen a wide range of pathogens, its simplicity to operate and a faster turnaround time. We conducted a three-center evaluation that compared the BioFire FilmArray gastrointestinal panel (FA GI) and real-time polymerase chain reaction (PCR) assays for the detection of pathogens from 462 clinical diarrhea specimens, and characterized the distribution of various pathogens that were analyzed. The sensitivity of FA GI was 100% for 13 pathogens and 93.8-98.3% for 4 pathogens, but low for Salmonella (60.5%) and adenovirus (88.9%). The sensitivity per pathogen of real-time PCR assays was lower than that observed with FA GI. The specificity of FA GI and real-time PCR assays per pathogen was greater than 94.5% and 99%, respectively. FA GI and real-time PCR assays detected ≥1 pathogen in 339 (73.4%) and 297 (64.3%) samples, respectively, and 324 (70.1%) samples were considered as positive according to the reference standard. Multiple pathogens were detected in 37.2% and 24.9% of samples by FA GI and real-time PCR assays, respectively. Norovirus GI/GII and Campylobacter were less associated with coinfections. The positive rates of some pathogens varied among the three regions of China. Molecular methods can help squickly identify the cause of diarrhea and provide valuable information for early diagnosis and optimal patient therapy.

Campylobacter culture fails to correctly detect Campylobacter in 30% of positive patient stool specimens compared to non-cultural methods

Campylobacter diagnosis is hampered because many laboratories continue to use traditional stool culture, which is slow and suffers false-negative results. This large multi-site study used a composite reference method consisting of a new FDA-cleared immunoassay and four molecular techniques to compare to culture. Prospectively collected patient fecal specimens (1552) were first preliminarily categorized as positive or negative by traditional culture. All specimens were also tested by EIA, and any EIA-positive or culture-discrepant results were further characterized by 16S rRNA qPCR, eight species-specific PCR assays, bidirectional sequencing, and an FDA-cleared multiplex PCR panel. The five non-culture methods showed complete agreement on all positive and discrepant specimens which were then assigned as true-positive or true-negative specimens. Among 47 true-positive specimens, culture incorrectly identified 13 (28%) as negative, and 1 true-negative specimen as positive, for a sensitivity of 72.3%. Unexpectedly, among the true-positive specimens, 4 (8%) were the pathogenic species C. upsaliensis. Culture had a 30% false result rate compared to immunoassay and molecular methods. More accurate results lead to better diagnosis and treatment of suspected campylobacteriosis.

Outbreak of Salmonella Typhimurium associated with feeder rodents

In December 2012, an increase in human Salmonella Typhimurium cases was identified in the province of Ontario, Canada launching an outbreak investigation. The outbreak spanned 3 years (2012-2014), with 134 cases reported from five Canadian provinces. There was a substantial burden of illness among children: 45% of cases were children 12 years old or under, and 23% of cases were under 5 years old. Epidemiologic, traceback and laboratory findings linked this outbreak to feeder rodents (used to feed snakes) supplied by a network of rodent breeders in Ontario. Cases likely acquired their illness through either direct or indirect contact with feeder rodents. This investigation not only contributes to the weight of evidence on the risk that feeder rodents pose, but also underscores the importance of investigating indirect animal contact and associated risks, especially for high-risk individuals.

Multiplex Molecular Panels for Diagnosis of Gastrointestinal Infection: Performance, Result Interpretation, and Cost-Effectiveness

Gastrointestinal disease is a major cause of morbidity and mortality worldwide, especially among young children and immunocompromised patients. Diarrhea may result from infection with a variety of microbial pathogens, including bacteria, viruses, or parasites. Historically, the diagnosis of infectious diarrhea has been made using microscopy, antigen tests, culture, and real-time PCR. A combination of these traditional tests is often required due to the inability to distinguish between infectious etiologies based on the clinical presentation alone. Recently, several multiplex molecular assays have been developed for the detection of gastrointestinal pathogens directly from clinical stool samples. These panels allow for the detection and identification of up to 20 pathogens in as little as 1 h. This review will focus on the multiplex molecular panels that have received clearance from the FDA for the diagnosis of diarrheal disease and will highlight issues related to test performance, result interpretation, and cost-effectiveness of these new molecular diagnostic tools.

Antibiotic susceptibility of clinical isolates of Campylobacter jejuni and Campylobacter coli in Ontario, Canada during 2011-2013

A total of 219 clinical isolates of Campylobacter spp. including 180 Campylobacter jejuni and 39 Campylobacter coli were assessed for in vitro antimicrobial susceptibility. Resistance among C. coli was higher for ciprofloxacin (41% versus 30.80%), erythromycin (12.80% versus 3.90%) and lower for tetracycline (53.80% versus 64.60%) compared to C. jejuni.

Comparative evaluation of two commercial multiplex panels for detection of gastrointestinal pathogens by use of clinical stool specimens

The detection of pathogens associated with gastrointestinal disease may be important in certain patient populations, such as immunocompromised hosts, the critically ill, or individuals with prolonged disease that is refractory to treatment. In this study, we evaluated two commercially available multiplex panels (the FilmArray gastrointestinal [GI] panel [BioFire Diagnostics, Salt Lake City, UT] and the Luminex xTag gastrointestinal pathogen panel [GPP] [Luminex Corporation, Toronto, Canada]) using Cary-Blair stool samples (n = 500) submitted to our laboratory for routine GI testing (e.g., culture, antigen testing, microscopy, and individual real-time PCR). At the time of this study, the prototype (non-FDA-cleared) FilmArray GI panel targeted 23 pathogens (14 bacterial, 5 viral, and 4 parasitic), and testing of 200 μl of Cary-Blair stool was recommended. In contrast, the Luminex GPP assay was FDA cleared for the detection of 11 pathogens (7 bacterial, 2 viral, and 2 parasitic), but had the capacity to identify 4 additional pathogens using a research-use-only protocol. Importantly, the Luminex assay was FDA cleared for 100 μl raw stool; however, 100 μl Cary-Blair stool was tested by the Luminex assay in this study. Among 230 prospectively collected samples, routine testing was positive for one or more GI pathogens in 19 (8.3%) samples, compared to 76 (33.0%) by the FilmArray and 69 (30.3%) by the Luminex assay. Clostridium difficile (12.6 to 13.9% prevalence) and norovirus genogroup I (GI)/GII (5.7 to 13.9% prevalence) were two of the pathogens most commonly detected by both assays among prospective samples. Sapovirus was also commonly detected (5.7% positive rate) by the FilmArray assay. Among 270 additional previously characterized samples, both multiplex panels demonstrated high sensitivity (>90%) for the majority of targets, with the exception of several pathogens, notably Aeromonas sp. (23.8%) by FilmArray and Yersinia enterocolitica (48.1%) by the Luminex assay. Interestingly, the FilmArray and Luminex panels identified mixed infections in 21.1% and 13.0% of positive prospective samples, respectively, compared to only 8.3% by routine methods.

A Markov model to estimate Salmonella morbidity, mortality, illness duration, and cost

Approximately 690000-1790000 Salmonella cases, 20000 hospitalizations, and 400 deaths occur in the USA annually, costing approximately $2.6bn. Existing models estimate morbidity, mortality, and cost solely from incidence. They do not estimate illness duration or use time as an independent cost predictor. Existing models may underestimate physician visits, hospitalizations, deaths, and associated costs. We developed a Markov chain Monte Carlo model to estimate illness duration, physician/emergency room visits, inpatient hospitalizations, mortality, and resultant costs for a given Salmonella incidence. Interested parties include society, third-party payers, health providers, federal, state and local governments, businesses, and individual patients and their families. The marginal approach estimates individual disease behavior for every patient, explicitly estimates disease duration and calculates separate time-dependent costs. The aggregate approach is a Markov equivalent of the existing models; it assumes average disease behavior and cost for a given morbidity/mortality. Transition probabilities were drawn from a meta-analysis of 53 Salmonella studies. Both approaches were tested using the 1993 Salmonella typhimurium outbreak in Gideon, Missouri. This protocol can be applied to estimate morbidity, mortality and cost of specific outbreaks, provide better national Salmonella burden estimates, and estimate the benefits of reducing Salmonella risk.