Gastrointestinal Pathogen Panel Research Articles

Detection and Characterization of Bacterial and Viral Acute Gastroenteritis among Outpatient Children under 5 Years Old in Guangzhou, China.

Acute gastroenteritis (AGE) in children can be attributed to a multitude of bacterial and viral pathogens. The objective of this study was to investigate the epidemiology of bacterial and viral AGE in children and to compare clinical characteristics between single and multiple enteric pathogen infections. A total of 456 stool samples were collected from outpatient children under 5 years old with AGE, which were subsequently analyzed for nine bacteria and three viruses using the Luminex xTAG® Gastrointestinal Pathogen Panel. The presence of at least one pathogen was detected in 260 cases (57.0%), with Salmonella being the predominant agent, followed by norovirus, Campylobacter, and rotavirus. A total of 69 cases (15.1%) exhibited positive results for two or more enteric pathogens. Although certain co-infections demonstrated significant differences in primary clinical features compared with mono-infections, no statistical variance was observed in terms of disease severity. In outpatient children from southern China, Salmonella emerged as the most prevalent causative agent of AGE, succeeded by norovirus and Campylobacter. This study underscores the burden posed by coinfections and highlights the clinical characteristics associated with AGE when accompanied by coinfections among children under 5 years old.

Epidemiological Surveillance: Genetic Diversity of Rotavirus Group A in the Pearl River Delta, Guangdong, China in 2019*

ObjectiveThis study aimed to understand the epidemic status and phylogenetic relationships of rotavirus group A (RVA) in the Pearl River Delta region of Guangdong Province, China. MethodsThis study included individuals aged 28 days–85 years. A total of 706 stool samples from patients with acute gastroenteritis collected between January 2019 and January 2020 were analyzed for 17 causative pathogens, including RVA, using a Gastrointestinal Pathogen Panel, followed by genotyping, virus isolation, and complete sequencing to assess the genetic diversity of RVA. ResultsThe overall RVA infection rate was 14.59% (103/706), with an irregular epidemiological pattern. The proportion of co-infection with RVA and other pathogens was 39.81% (41/103). Acute gastroenteritis is highly prevalent in young children aged 0–1 year, and RVA is the key pathogen circulating in patients 6–10 months of age with diarrhea. G9P[8] (58.25%, 60/103) was found to be the predominant genotype in the RVA strains, and the 41 RVA-positive strains that were successfully sequenced belonged to three different RVA genotypes in the phylogenetic analysis. Recombination analysis showed that gene reassortment events, selection pressure, codon usage bias, gene polymorphism, and post-translational modifications (PTMs) occurred in the G9P[8] and G3P[8] strains. ConclusionThis study provides molecular evidence of RVA prevalence in the Pearl River Delta region of China, further enriching the existing information on its genetics and evolutionary characteristics and suggesting the emergence of genetic diversity. Strengthening the surveillance of genotypic changes and gene reassortment in RVA strains is essential for further research and a better understanding of strain variations for further vaccine development.

Multicenter evaluation of BioCode GPP for syndromic molecular detection of gastrointestinal pathogens from stool specimens.

This study highlights performance of a novel technology for timely and accurate detection and differentiation of 17 common bacterial, viral, and protozoan causes of gastroenteritis. Utilizing molecular tests such as the BioCode Gastrointestinal Pathogen Panel may improve the detection of gastrointestinal pathogens and provide actionable results, particularly for patient populations at most risk.

QIAstat-Dx gastrointestinal panel and Luminex xTAG gastrointestinal pathogen panel comparative evaluation.

The diagnosis of acute gastroenteritis is an ongoing clinical challenge in terms of identification of the etiologic agent, time to results, and appropriate treatment. Rapid detection of gastrointestinal pathogens is needed to improve patient care. This study evaluates the performance of the QIAstat-Dx gastrointestinal panel (Q-GP; Investigational Use Only) compared to the Luminex xTAG gastrointestinal pathogen panel (L-GPP; US-IVD). Using 245 stool specimens, we evaluated 10 different targets including rotavirus, norovirus, Salmonella, Shigella, Campylobacter, Giardia, Cryptosporidium, Escherichia coli O157, enterotoxigenic E. coli (ETEC), and Shiga toxin-producing E. coli (STEC). For the viral targets, the percent positive agreement (PPA) for rotavirus was 100% (n = 19) and that for norovirus was 91% (20/22). For the parasitic targets, the PPA was 100% for Giardia and Cryptosporidium (n = 18 and n = 23, respectively). The PPA was 96% for Salmonella (22/23) and Campylobacter (22/23), and the PPA for Shigella was 100% (n = 23). For the E. coli targets, a PPA of 94% was achieved for STEC (32/34) and 96% for ETEC (24/25). We did not assess PPA for the E. coli O157 target as the Q-GP O157 call is stx dependent. The negative percent agreement across all targets was 99.1%. Our study suggests that QIAstat-Dx GP provides comparable results to Luminex GPP based on the analysis of targets found on both panels.

Prevalence of Enteric Infections in Patients on Immune Checkpoint Inhibitors and Impact on Management and Outcomes.

Stool pathogen testing is recommended as part of the initial evaluation for patients with new-onset diarrhea on immune checkpoint inhibitors (ICIs), yet its significance has not been well-studied. We aimed to determine the impact of multiplex gastrointestinal (GI) pathogen PCR testing on the clinical course and use of immunosuppressive therapy in patients who develop diarrhea on ICIs. This retrospective cohort included individuals who underwent GI pathogen panel PCR for diarrhea on ICIs at Memorial Sloan Kettering between 7/2015 and 7/2021. The primary outcome was use of immunosuppressive therapy for suspected immunotherapy-related enterocolitis (irEC). Secondary outcomes included diarrhea severity and endoscopic and histologic disease patterns. Among 521 ICI-treated patients tested for GI pathogens, 61 (11.7%) had a positive PCR. Compared to patients without detectable infections, patients with infections had more frequent grades 3-4 diarrhea (37.7% vs. 19.6%, P < .01) and colitis (39.3% vs. 14.7%, P < .01). However, patients with infections did not have higher rates of persistent or recurrent diarrhea and were less likely to receive steroids (P < .01) and second-line immunosuppressive agents (P = .03). In 105 patients with lower endoscopy, similar trends were observed and no differences in endoscopic severity or histologic patterns were noted between groups. GI infections in ICI-treated patients presenting with diarrhea are linked to more severe but self-limited clinical presentations and may be optimally treated with observation and supportive care alone. Routine and timely stool pathogen testing may help avert unnecessary empiric immunosuppression for suspected irEC, which has been linked to blunted antitumor responses and numerous adverse effects.

Summer diarrhea in children: a monocentric French epidemiological observational study

Pediatric diarrhea is a major public health problem worldwide. In France, continuous surveillance shows a winter epidemic peak and a more modest summer recrudescence. Few studies describe the infectious agents responsible for pediatric summer diarrhea in France. The objectives were to estimate the prevalence of infectious diarrhea and describe the pathogens responsible for summer diarrhea in children; and to describe common factors that can be used as guidance on the etiology of these diarrheas. A cross-sectional, single-center, epidemiological observational study was conducted in the pediatric emergency department of a French hospital between June and September in 2019 and 2020. Multiplex gastrointestinal pathogen panels were used for diagnostics. A multiple correspondence analysis was used to determine profiles of patients. A total of 95 children were included, of whom 82.1% (78/95) were under five years old. The prevalence of infectious summer diarrhea was 81.1% (77/95, 95%CI 71.7–88.4%). A total of 126 infectious agents were detected (50.0% bacteria, 38.1% viruses, 11.9% parasites). The main enteric pathogens were enteropathogen Escherichia coli (24/126), rotavirus (17/126) and Salmonella (16/126). A co-detection was found in 51.9% (40/77) of cases. Four patient profiles, considering the severity and the pathogen involved, were highlighted.

Utility and Recommendations for the Use of Multiplex Molecular Gastrointestinal Pathogen Panels.

Many molecular gastrointestinal pathogen panels (GIPs) are Food and Drug Administration (FDA) cleared but it is still unclear how to best utilize these new diagnostic tools. GIPs are highly sensitive and specific, simultaneously detect multiple pathogens in one reaction, and can shorten the overall time of diagnosis for infectious gastroenteritis but are also expensive with relatively poor insurance reimbursement. In this review, we take a comprehensive approach to discuss issues with utilization of GIPs from a physician perspective, and implementation from a laboratory perspective. The information presented is to assist physicians in deciding on appropriate use of GIPs in diagnostic algorithms for their patients, and to provide information to laboratories that may be considering the addition of these powerful diagnostic assays to their test menu. Some of the important topics discussed are inpatient vs outpatient use, the appropriate panel size and organisms to include, interpretation of results, laboratory validation, and reimbursement. The information in this review provides clear guidance to both clinicians and laboratories in deciding the best use of GIPs for a specific patient population. While this technology provides many benefits over traditional methods, it can also complicate result interpretation and comes with a high cost, which necessitates the need for use recommendations.

2001. Clinical management changes after positive multiplex gastrointestinal pathogen panel testing for evaluation of diarrhea

Abstract Background IDSA guidelines for diarrhea include pathogen-specific management. Compared to non-molecular tests, multiplex gastrointestinal pathogen panels (GIPPs) may allow for more timely and cost-effective diagnoses and care. However, this has yet to be definitively demonstrated. Our objective was to determine the impact of positive GIPP results on clinical management, including antimicrobial use. Methods We performed a retrospective study of patients with diarrhea and a positive GIPP result (xTAG Gastrointestinal Pathogen Panel, Luminex) at an academic, tertiary-care medical center from January-December 2018. We excluded immunocompromised patients (solid organ or stem cell transplant, HIV with absolute CD4 count &amp;lt; 200 cells/µL, primary immunodeficiency, and immunosuppressive medications including biologics). We collected patient and clinical data via electronic medical record review. Our primary outcome of interest was change in antimicrobial usage. Results A total of 2,333 GIPP tests were performed of which 266 (11.4%) were positive. Of 193 patients who met inclusion criteria, 34% were tested in an emergency room, 38% in outpatient clinics, and 29% on inpatient wards. Of these, 55% were men, 65% were white, and the median age was 31 years (interquartile range, IQR 5-56). The median turnaround time from GIPP collection to result was 31 hours (IQR 24-53). The most frequently identified pathogens were norovirus, Salmonella, and Campylobacter (Figure 1). In 43% of patients, results led to one or more management changes including antibiotic discontinuation (8%) and antibiotic initiation (25%). Antibiotics were most often discontinued for norovirus (Figure 1A) and started for Campylobacter (Figure 1B). Other management changes occurred in 13% of patients, including avoidance of further diagnostic testing and isolation precaution change. The median turnaround time did not differ for GIPPs that were (30 hours; IQR 22-50) or were not (32 hours; IQR 25-56) associated with management change. Conclusion Positive GIPP results can prompt changes in antimicrobial treatment in non-immunocompromised patients with diarrhea. Future efforts will evaluate the appropriateness of these management changes. Disclosures Melissa B. Miller, PhD, Abbott Molecular: Grant/Research Support|Agena Biosciences: Board Member|ArcBio: Grant/Research Support|Cepheid: Board Member|Luminex Molecular Diagnostics: Board Member|QIAGEN: Board Member|QIAGEN: Grant/Research Support|Sherlock Biosciences: Advisor/Consultant|Talis Biomedical: Board Member|Thermo Fisher: Honoraria|Werfen: Board Member.

2153. Clinical Characteristics and Pathogen Detection in Children with Symptoms of Acute Respiratory Illness and Acute Gastroenteritis

Abstract Background Children can present with overlapping symptoms of acute respiratory illness (ARI) and acute gastroenteritis (AGE). In these cases, it is unclear if the etiologic agent is a respiratory pathogen, gastrointestinal pathogen, or both. Methods We analyzed data collected in Nashville, TN (12/01/2016–2/28/2020) as part of the New Vaccine Surveillance Network, a prospective ARI/AGE surveillance study. Children (&amp;lt; 18 years old) who presented to the emergency department or were admitted with fever and/or respiratory symptoms for &amp;lt; 14 days were enrolled as ARI subjects and had mid-turbinate nasal ± throat swabs collected, while children with ≥1 episode of vomiting and/or ≥3 episodes of diarrhea in 24 hours were enrolled as AGE subjects and had stool collected. Children who met both sets of criteria were dually enrolled. Respiratory specimens were tested for common respiratory viruses by molecular testing and stool specimens were tested for common gastrointestinal (GI) pathogens by Luminex GI Pathogen Panel. We compared detection groups using Pearson’s χ2 test. C. difficile detection in children &amp;lt; 2 years old was considered asymptomatic carriage (n=32). Results We identified 501 dual enrollees, among whom 279 (55.7%) had both a respiratory and stool specimen tested. Overall, 127 (45.5%) had only a respiratory virus detected, 33 (11.8%) had only a GI pathogen detected, 39 (14.0%) had both, and 77 (27.6%) had no detection (Table 1). Vomiting and diarrhea were frequently reported ( &amp;gt;50%) in all dual enrollees whether or not a pathogen was detected (Figure 1). Cough was detected in high frequency in all groups with pathogen detection. Children with respiratory-only or dual detection had a higher frequency of wheezing and shortness of breath than those with GI-only or no detection. The distribution of pathogens did not significantly differ between single and co-detected cases (Figure 2). Table 1Demographic characteristics of N=279* children presenting with symptoms of acute respiratory illness and acute gastroenteritis in Nashville, TN, stratified by detection status.Figure 1Distribution of signs and symptoms in N=279 children presenting with symptoms of acute respiratory illness and acute gastroenteritis in Nashville, TN, stratified by detection status. p values represent omnibus comparisons of all four groups.Figure 2Distribution of pathogens detected in N=279 children presenting with symptoms of acute respiratory illness and acute gastroenteritis in Nashville, TN, stratified by detection status. Conclusion Children presenting with overlapping symptoms of ARI and AGE were more likely to have an ARI-associated virus. Lower respiratory symptoms (namely, wheezing and shortness of breath) were more specific for ARI-associated viral detection compared with other signs and symptoms. Disclosures Natasha B. Halasa, MD, Quidel: Grant/Research Support|Quidel: equipment donation|Sanofi: Grant/Research Support|Sanofi: HAI testing and vaccine donation.

Comparative Evaluation of Luminex xTAG® Gastrointestinal Pathogen Panel and Direct-From-Stool Real-Time PCR for Detection of C. difficile Toxin tcdB in Stool Samples from a Pediatric Population.

Detection of Clostridioides difficile toxins in patients with gastroenteritis has increasingly been accomplished through the use of enteric multiplex syndromic panels. Comparisons of the performance of these panels to both direct-from-stool (DFS) and culture-enriched stools followed by polymerase chain reaction (PCR) methods in pediatric populations are limited. Here, we compare the performance of the Luminex xTAG® Gastrointestinal Pathogen Panel (GPP) to our DFS in-house real-time PCR (DFS RT-PCR) assay for the detection of C. difficile toxin gene, tcdB, using 2641 stool specimens collected from children enrolled in the Alberta Provincial Pediatric EnTeric Infection Team (APPETITE) study in Alberta, Canada. We used culture enrichment followed by in-house RT-PCR to resolve discordant results between the two assays. We found excellent agreement (k = 0.89) between the GPP and our DFS RT-PCR assay: the positive percent agreement between the two assays was 97%, and the negative percent agreement was 99%. GPP, a multi-analyte platform can easily be implemented into a routine diagnostic laboratory for detecting enteric pathogens including C. difficile.

S2741 Ischemic Colitis Imitating Inflammatory Bowel Disease

Introduction: Inflammatory bowel disease (IBD) and ischemic colitis (IC) are two different entities that can present similarly. There have been case reports of Crohn’s disease mimicking IC in elderly population. In contrast, we present a case of a young patient whose clinical history was consistent with IBD, but he was ultimately found to have IC on biopsy results. Case Description/Methods: A 36-year-old male with a history of type I diabetes mellitus, hypothyroidism as well as family history significant for IBD presented with abdominal pain, nausea, emesis, and diarrhea. In the emergency room, he was afebrile and hemodynamically stable with BP of 121/88 mmHg and HR of 90 BPM. Labs were significant for mild leukocytosis and normal lipase. Computed tomography of abdomen pelvis with contrast revealed diffuse colonic thickening concerning for acute colitis. C. difficile and gastrointestinal pathogen panel were negative. The day after admission, he was found to have intermittent episode of hematochezia along with elevated fecal calprotectin and c-reactive protein at 2945 ug/g and 38 MG/L respectively. Patient’s elevated inflammatory marker in setting of negative infectious work up, family, and personal history of autoimmune diseases were concerning for IBD. Patient underwent colonoscopy which revealed large ulcerated, edematous, and erythematous area in the mid-distal proximal transverse colon (50-80cm from the anal verge) (Figure) with rest of colonic mucosa and terminal ileum appearing normal. Biopsies from the mid transverse colon showed paucicellular lamina propria with edema, hyalinization, vascular dilation, and congestion consistent with ischemic colitis without any significant crypt architectural distortion, basilar lymphoplasmacytosis or evidence of metaplasia. Precipitant for ischemic colitis was unclear in this patient. He was treated symptomatically for ischemic colitis and had symptomatic improvement at time of discharge. Discussion: It is essential to consider IC in a young patient with family and personal history of autoimmune disease presenting with signs and symptoms typical for IBD as IC can mimic IBD. Timely and proper diagnosis is necessary as treatment for these two disorders is completely different. IBD can require medications like biologics which may have dangerous side effects if used inappropriately where IC is managed symptomatically.Figure 1.: Colonoscopy showing large edematous and erythematous area in the mid-distal proximal transverse colon.

S2239 An Uncommon Case of Neglected Yersinia enterocolitica Presenting as Anemia in Northeast America

Introduction: Yersinia is a facultative anaerobic gram-negative coccobacillus. Most infections are caused by eating and the contamination of food and water by infected animals. It causes fever, abdominal pain, which may mimic appendicitis, and bloody diarrhea, mostly in children due to cross-contamination of their feeds. Necrotizing enterocolitis can occur in infants. It is not commonly seen on the East Coast of the United States for an older adult with no iron overload conditions. Case Description/Methods: Our patient is an 88-year-old male with an extensive history of coronary artery disease presented with sudden onset of emesis, abdominal pain, and bloody stools. He had no chills or fever. At presentation, he was obese, pale, lethargic, oriented, and in no distress. His temperature was 98.5 F, Heart Rate was 84 beats per minute, blood pressure was 94/54mmHg, and SpO2 was 99% on room air. He had mottled skin on the legs with pitting edema. The abdominal examination was normal except for a mild tenderness in the left lower quadrant. The rest of the systemic review was normal. Computed Tomography (CT) abdomen showed mild wall thickening in the left colon, suggesting colitis. He received intravenous (IV) saline boluses and was then started on IV fluids, Zosyn, Unasyn, and Protonix. He needed pressor support and Intensive Care Unit admission for a brief time. Gastro duodenoscopy and flexible sigmoidoscopy showed 2 clean-based Antral ulcers with no bleeding and a circumferential inflammation of the right colon with ulcerated and friable mucosa. Gastrointestinal Pathogen Panel by PCR was positive for Yersinia enterocolitica, and he was started on IV Doxycycline. This led to his improvement, and he was eventually discharged in a stable condition (Figure). Discussion: The centers for Disease Control and Prevention (CDC) monitors the frequency of Y. enterocolitica infections. In 2020 the incidence of yersiniosis was less than 0.30 per 100,000. Infections are usually self-limited, but they can cause sepsis with up to a 50% fatality rate in people with iron overload conditions like thalassemia, hemochromatosis, and blood transfusions. It causes pseudoappendicitis, mesenteric lymphadenitis, and endocarditis in susceptible adults. Reactive arthritis affecting the wrists, knees, and ankles is seen in people with HLA-B27. Erythema nodosum can occur. Bacterial shedding can continue for up to 3 months after recovery. Hence, its detection is vital to contain the spread.Figure 1.: CT Abdomen showing mild wall thickening seen in the colon suggesting colitis.

The role of gastrointestinal pathogen polymerase chain reaction testing in liver transplant recipients hospitalized withdiarrhea.

Diarrhea is a common symptom among liver transplant (LT) recipients and can result in significant morbidity. The utility of PCR-based multiplex gastrointestinal (GI) pathogen panels in this population is unknown. We assessed incidence, predictors, and outcomes of GI PCR positivity among inpatients who underwent stool pathogen testing with the FilmArray multiplex GI PCR panel at our institution within 1 year following LT from April 2015 to December 2019. A total of 112 patients were identified. Of these, 14 (12.5%) had a positive PCR for any pathogen. Escherichia coli (n=9) and Norovirus (n=5) were the most common pathogens detected. Recipients with a positive PCR were significantly further from LT (median 74.5vs. 15.5 days, p<.01) and tested earlier during hospitalization (median 1.0vs. 9.0 days, p<.01). C. difficile was positive in 20.0% of patients with a positive PCR and 11.4% with a negative PCR. CMV viremia was observed in 11.6% of patients, all in the negative PCR group. Following a positive PCR, patients were more likely to have a change in antimicrobial regimen (71.4%vs. 28.6%, p=.02), a shorter length of stay (median 7.5vs. 17.5 days, p<.01), and a trend toward lower rates of readmission and colonoscopy within 30days. In hospitalized LT recipients with diarrhea, GI PCR pathogen identification was associated with the use of targeted antimicrobial therapy and a shorter length of stay. GI PCR testing should be considered early during admission and later in the post-LT period.

Yersinia Enterocolitica Sepsis in an Elderly Male With No Iron Overload: A Case Report From the Northeastern United States

Yersinia enterocolitica (YE) is a facultative anaerobic gram-negative coccobacillus of the genus Yersinia (the most common ones are YE serogroups O:3; O:5,27; O:8; and O:9). Its incubation period is typically 1-14 days. The symptoms of YE infection include fever, abdominal pain (which may mimic appendicitis), and diarrhea (which may be bloody and can persist for several weeks). It is most commonly reported in infants and children due to cross-contamination of their feeds and pacifiers by people handling pork products, especially while cooking chitterlings. Necrotizing enterocolitis has been described in infants following YE infections. Adults who are immunocompromised or in an iron-overload state can develop sepsis with YE infection, which has a high fatality rate. Post-infectious sequelae like reactive arthritis and erythema nodosum can occur in certain HLA types. The diagnosis is made by isolating the organism from the body fluids, stool. The gastrointestinal (GI) pathogen panel by polymerase chain reaction (PCR) is helpful in making an early diagnosis. In this report, we discuss a case of an elderly male from a nursing facility who presented with abdominal pain, vomiting, GI bleeding, and sepsis. He required a brief ICU stay and pressor support. GI pathogen panel was instrumental in the early diagnosis of YE. This condition is not often reported in the Northeastern US. Using GI pathogen PCR testing will lead to the detection of more cases of YE in geographical regions where it was not considered prevalent.

668. Restricting Ordering of Multiplex Gastrointestinal Panel Improves Test Utilization

BackgroundThe multiplex gastrointestinal pathogen panel (GIP) is a convenient and quick diagnostic test for determining the infectious etiology of diarrhea. It identifies several of the most common pathogens associated with gastroenteritis. However, it is expensive, and test results may not impact care, given that several of the pathogens in the panel are managed expectantly. We describe our experience with a diagnostic stewardship initiative to resolve the overuse of this testing method. MethodsWe performed a pre/post study of GIPs ordered for inpatients 18 years old and older from December 19, 2018, to December 18, 2020, at Mayo Clinic hospital in Rochester, Minnesota. GIP orders for inpatients were limited to the first 72 hours of hospitalization starting December 19, 2019. Orders after 72 hours were encouraged to be changed to Clostridioides difficile NAAT testing or sent to an infectious disease provider to override on a case-by-case basis. Our hospitals used BioFire® FilmArray® Gastrointestinal Panel (BioFire Diagnostics, Salt Lake City, Utah).ResultsA total of 2,641 GIPs were performed during the study period. There were 1,568 GIPs (3.3/100 hospitalizations) in the pre-intervention period compared to 1,073 (2.6/100 hospitalizations) post-intervention, representing a drop of 21.2%. The most common pathogen detected was C. difficile (toxin A/B) (48.8%, n=402), followed by norovirus (17.5%, n=144). The overall test positivity rate was 27.9% (n=736). The test positivity rate decreased 1.8% from 28.6% (n=448) to 26.8% (n=288) after the restriction (p=0.33). The proportion of C. difficile among all pathogens detected increased from 48.5% to 49.7% (p=0.67).Table 1. Pre- and Post-Intervention Test Positivity Rate of Specific Pathogens in GIP ConclusionOur study showed that restricting the ordering of GIP to the first 72 hours of hospitalization and directing providers to standalone C. difficile NAAT testing resulted in a reduction of GIPs performed. There were marginal changes in the test positivity rate of GIP. A limitation of our study is that the timing of post-intervention coincided with the COVID-19 pandemic, which had unpredictable effects on hospital practice and patient admissions. Ideally, future quality improvement projects should increase the test positivity of pathogens other than C. difficile while lowering the GIP use in diagnosing C. difficile colitis. Disclosures John C. O'Horo, Sr., MD, MPH, Bates College and Elsevier Inc (Consultant)

927. Clinical Characteristics and Outcomes of Norovirus Infection in Patients with Hematologic Malignancies: A Retrospective, Single Center Study

BackgroundNorovirus (NV) gastroenteritis has been identified as a cause of significant morbidity among hematopoietic stem cell transplant (HSCT) recipients, often with associated complications. Current guidelines recommend symptomatic relief with antimotility agents, rehydration, and reduction in immune suppression. Nitazoxanide (NTZ) is an anti-parasitic agent but some literature suggests a benefit of nitazoxanide therapy for NV. MethodsWe conducted a single center, retrospective chart review study and evaluated adult patients (age >18 years) who had NV infection and either: 1) underwent stem cell transplantation; or 2) received myeloablative chemotherapy within 4 weeks of NV diagnosis by positive test on gastrointestinal pathogen panel during the time period from January 2015 through March 2020. Results26 patients were reviewed. 14 patients (54%) had a history of HCST prior to infection. Three patients (12%) received both myeloablative chemotherapy and HSCT within four weeks of NV infection. Six patients (46%) had autologous, six (46%) had matched unrelated donor, and one (8%) had haploidentical allogeneic transplants. Nine (69%), three (23%), and one (8%) underwent myeloablative, reduced intensity and non-myeloablative conditioning, respectively. Median duration of diarrhea was 4.5 days (IQR = 2.25-7 days). Three (12%) patients received NTZ or intravenous immune globulin. The 6 month mortality was 42% (11/26), however, none of the deaths were directly attributable to NV infection.ConclusionNV infection led to severe diarrheal disease in our cohort. Overall mortality was high, and a trend toward increased mortality was seen among patients receiving NV-directed therapy; these patients likely received NV-directed therapy due to the severity of their illness. Clinicians must have a high suspicion for this illness and obtain PCR testing for timely diagnosis and management.Table 1. Characteristics of patients with hematologic malignancies and norovirus infection Disclosures All Authors: No reported disclosures

Detection and characterization of human astrovirus and sapovirus in outpatients with acute gastroenteritis in Guangzhou, China

BackgroundHuman astrovirus (HAstV) and sapovirus (SaV) are common pathogens that can cause acute gastroenteritis (AGE). However, very few studies have reported the molecular epidemiology and clinical information on HAstV and SaV in China. This study aims to determine the molecular epidemiology and clinical features of HAstV and SaV in patients with AGE in Guangzhou, China.MethodsFor this study, 656 patients with AGE were enrolled. Their stool samples were screened for 15 enteropathogens using Luminex xTAG® Gastrointestinal Pathogen Panel. HAstV and SaV were detected through an in-house multiplex reverse transcriptase polymerase chain reaction followed by phylogenetic analysis. We described and compared clinical features of AGE in patients with HAstV and SaV.ResultsOf the 656 stool samples, 63.72% (418/656) were found to be positive, with 550 enteropathogens (296 bacteria and 254 viruses). HAstV and SaV were detected in 20 (3.0%) and 12 (1.8%) samples, respectively. Four genotypes (genotypes 1, 2, 3, and 8) of HAstV and three genotypes (GI.1, GI.2 and GIV) of SaV were identified. Coinfection was observed in ten HAstV-positive and two SaV-positive samples. HAstV was more likely to occur in winter, while SaV in early spring. The median age of the patients with single HAstV infection was higher than that of the patients with other viruses (rotavirus, norovirus, and enteric adenovirus; P = 0.0476) and unknown etiology (P = 0.006). Coinfection with HAstV or SaV were not associated with disease severity (P > 0.05).ConclusionHAstV and SaV are the common causes of AGE in Guangzhou, China.

Multiplex PCR Pathogen Detection in Acute Gastroenteritis Among Hospitalized US Children Compared With Healthy Controls During 2011-2016 in the Post-Rotavirus Vaccine Era.

BackgroundDespite vaccine-induced decreases in US rotavirus (RV) disease, acute gastroenteritis (AGE) remains relatively common. We evaluated AGE pathogen distribution in hospitalized US children in the post–RV vaccine era.MethodsFrom December 2011 to June 2016, the New Vaccine Surveillance Network (NVSN) conducted prospective, active, population-based surveillance in hospitalized children with AGE. We tested stools from 2 NVSN sites (Kansas City, Houston) with Luminex x-TAG Gastrointestinal Pathogen Panels (Luminex GPP) and analyzed selected signs and symptoms.ResultsFor 660 pediatric AGE inpatients and 624 age-matched healthy controls (HCs), overall organism detection was 51.2% and 20.6%, respectively (P < .001). Among AGE subjects, GPP polymerase chain reaction detected >1 virus in 39% and >1 bacterium in 14% of specimens. Detection frequencies for AGE subjects vs HCs were norovirus (NoV) 18.5% vs 6.6%, RV 16.1% vs 9.8%, adenovirus 7.7% vs 1.4%, Shigella 4.8% vs 1.0%, Salmonella 3.1% vs 0.1%, and Clostridioides difficile in ≥2-year-olds 4.4% vs 2.4%. More co-detections occurred among AGE patients (37/660, 5.6%) than HCs (14/624, 2.2%; P = .0024). Per logistic regression analysis, ill contacts increased risk for NoV, RV, and Shigella (P < .001). More vomiting episodes occurred with NoV and RV, and more diarrheal episodes with Shigella and Salmonella. Modified Vesikari scores were highest for Shigella and lowest for C. difficile.ConclusionsNoV detection was most frequent; however, RV remained important in hospitalized AGE in the post–RV vaccine era. Continued active surveillance is important to document ongoing vaccine effects, pathogen emergence, and baseline disease burden for new vaccines.

S1853 Gastrointestinal AL Amyloidosis: A Rare Cause of Symptomatic Colitis

Introduction: Gastrointestinal (GI) symptoms of systemic diseases are often poorly characterized. Evaluation of intractable symptoms may include advanced studies, such as computed tomography (CT) and magnetic resonance imaging scans, esophagogastroduodenoscopy (EGD) and colonoscopy. Amyloidosis, characterized by the extracellular deposition of insoluble misfolded proteins, can result in the deposition of abnormal proteins into the GI tract. GI amyloidosis (GIA) is difficult to diagnose and treat due to its variable etiologies and clinical manifestations. Current literature on GIA is vastly limited to case reports. We describe a case of GIA diagnosed by colonic biopsy. Case description/methods: 77-year-old female with past medical history of hypertension and chronic kidney disease presented with nausea, vomiting, diarrhea, left lower quadrant pain (LLQ) , anorexia, and a 20-pound weight loss. She was evaluated five months prior and treated for dyspepsia without relief. A recent CT scan of her abdomen revealed transverse, descending, and sigmoidal colonic wall thickening consistent with colitis. Antibiotics failed to improve her symptoms and unfortunately resulted in Clostridium difficile colitis. On physical exam, she was hypotensive, tachycardic, tender to palpation in the LLQ, and had 1+ pitting pedal edema. Labs revealed a leukocytosis, and anemia with hemoglobin 9.4 g/dL. GI pathogen panel was negative. Repeat CT scan revealed a thickened gastric wall in addition to previously noted colonic wall thickening. EGD and flexible sigmoidoscopy noted gastritis, duodenitis, and diffusely friable exudative colonic mucosa with underlying fibrosis (Figure 1). Pathology revealed extensive amyloid deposition. Bone marrow biopsy with flow cytometry showed plasma cell myeloma, confirming the diagnosis of GIA. Discussion: GIA is differentiated by systemic versus localized forms; the incidence of AL amyloidosis is approximately 1/100,000 in Western countries. Studies have shown that biopsy proven GIA is a rare phenomenon, consisting of as little as 3.3% of all cases. The most common symptoms of GIA are GI bleeding, malabsorption, nausea, vomiting, and protein-loss gastroenteropathies. Clinicians should be aware of these symptoms in elderly patients so that GIA can be diagnosed and treated early to minimize morbidity and mortality.Figure 1.: Endoscopic images demonstrating diffusely friable, exudative mucosa at the splenic flexure (A), descending colon (B,C) and sigmoid colon (D,E,F).

S1975 Multiplex Gastrointestinal Pathogen Panel Testing Is Associated With Higher Diagnostic Yield and Identification of Pathogenic E. coli Species in Patients With Travelers’ Diarrhea

S1975 Multiplex Gastrointestinal Pathogen Panel Testing Is Associated With Higher Diagnostic Yield and Identification of Pathogenic E. coli Species in Patients With Travelers’ Diarrhea