Positive Enzyme-linked Immunosorbent Assay Research Articles

Determining Diagnostic Sensitivity: A Comparison of Rose Bengal Test, Coombs Gel Test, ELISA and Bacterial Culture in Brucellosis Diagnosis—Analyzing Clinical Effectiveness in Light of Inflammatory Markers

Background: Brucellosis is a zoonotic infectious disease. It is estimated that the number of cases reported today is much less than the actual number. We still have difficulty in diagnosing the disease and its organ involvement. In this sense, new approaches that can be useful in clinical practice are required, and we aimed to evaluate this situation in our study. Methods: 171 of 213 patients followed in our center between January 2021 and April 2024 were included in the study. A total of 150 patients were included in the study as a control group. Rose Bengal test (RBT), Coombs gel test (CGT), enzyme-linked immunosorbent assay (ELISA), and automated blood culture were used for diagnosing brucellosis. Complete blood count, sedimentation, C-reactive protein, and biochemical parameters were obtained. Inflammation markers such as neutrophil–lymphocyte ratio, platelet–lymphocyte ratio, systemic immune-inflammation index, and systemic inflammation response index were calculated. Results: The most successful results in the diagnosis were ELISA (89.4%), RBT (88.3%), CGT (83%), and blood culture (34.8%). For diagnosing sacroiliitis and spondylodiscitis, instead of resorting to expensive methods like magnetic resonance, a combination of ELISA positivity with elevated acute phase reactants and inflammatory markers could be significantly instructive. Conclusions: Optimizing diagnostic algorithms and exploring novel diagnostic approaches, such as inflammatory markers, hold promise for improving diagnosis and management.

Visceral Leishmaniasis in a Twin Pregnancy: A Case Report and Review of the Literature.

Visceral leishmaniasis (VL), often referred to as kala-azar, is quite rare in developed countries during pregnancy. Only few studies have evaluated its impact on perinatal outcome. It is caused primarily by Leishmania donovani or Leishmania infantum and presents with a wide spectrum of clinical manifestations from cutaneous ulcers to multisystem disease. Differential diagnosis is challenging as symptoms and signs are insidious, mimicking other diseases. Misdiagnosis can result in severe adverse perinatal outcomes, even maternal/neonatal death. Early treatment with liposomal amphotericin-B (LAmB) is currently the first choice with adequate effectiveness. We report a rare case of VL in a twin pregnancy with onset at the second trimester, presenting with periodic fever with rigors, right flank pain, and gradual dysregulation of all three cell lines. The positive rK39 enzyme-linked immunosorbent assay test confirmed the diagnosis. Treatment with LAmB resulted in clinical improvement within 48 h and in the delivery of two late-preterm healthy neonates with no symptoms or signs of vertical transmission. The one-year follow-up, of the mother and the neonates, was negative for recurrence. To our knowledge, this is the first reported case of VL in a twin pregnancy, and consequently treatment and perinatal outcome are of great importance.

Clinical significance of viral markers testing by ELISA and Individual Donation Nucleic Acid Testing (ID-NAT) for blood screening in blood bank: Single center study in Egypt

Prevention of transfusion-transmitted viral infections and insurance of safe blood transfusion are the main goals of all blood banks worldwide. Despite the high sensitivity and specificity of currently used enzyme linked immunosorbent assay (ELISA) for hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) testing, viral transmission could still occur during the window period. Introducing viral individual donation nucleic acid testing (ID-NAT) can greatly decrease such risk providing an additional layer in securing blood transfusion. We aimed to assess the clinical significance of viral markers testing by ELISA and ID-NAT for blood screening in the Blood Bank of Suez Canal University Hospital. We studied all donations (2132) collected during a two-months period. Blood donor samples were screened by ELISA and ID-NAT tests for HBV, HCV, and HIV. Serological testing results for HCV by ELISA revealed 2,122 (99.5 %) negative donations compared to 2,131 (99.95 %) negative donations by ID-NAT testing. Of the positive ELISA samples, only one was NAT positive. For HBV ELISA testing, 2,115 (99.2 %) donations were negative, also by ID-NAT testing 2,115 (99.2 %) donations were HBV DNA negative. Out of the negative ELISA samples, two samples were ID-NAT reactive donors which were missed by serology assay being in the window period. HIV ELISA testing revealed negative 2,130 (99.9 %) donations while ID-NAT testing showed 2,131 (99.95 %) negative donations and one positive donation. In conclusion, this is the first study carried out in the Suez Canal and Sinai region, Egypt to assess the importance of ID-NAT implementation. The introduction of ID-NAT in blood banks is an effective method for increasing safety of the blood transfusion.

Seroprevalence of Infection by Borrelia Species Responsible for Lyme Disease in the French Alps: Analysis of 27,360 Serology Tests, 2015-2020.

Objectives: Lyme borreliosis incidence is increasing in several areas; moreover, it has recently gained the public's attention. Apart from erythema migrans, Lyme disease diagnosis relies (among others) on serology test; however, the prevalence of positive enzyme-linked immunosorbent assay (ELISA) and western blot (WB) assay has been poorly studied in the general population. We aimed to approach the seroprevalence of infection by Borrelia species responsible for Lyme disease in the French Isere department using city laboratories data. Patients and Methods: We retrieved all serological tests for Borrelia species responsible for Lyme disease performed in the two main networks of city laboratories between 2015 and 2020. All patients with both ELISA and WB IgG were considered seropositive. Results: We analyzed 27,360 tests (ELISA/ELISA+WB). Mean age was 50.9 ± 20.3 years (ranges: 0-101), with 57.1% females. Overall, 11.7% had IgG detected by ELISA, and 4.7% had IgG detected by both ELISA and WB assay. Seropositive status was more frequent in males (7.0% vs. 2.9%, p < 0.001). Seropositivity rate increased with age after a first peak in childhood; men aged 61-70 years had the highest seropositivity rate (10.3%). In addition, seropositivity rate was higher in persons from a rural area. In multivariate analysis, older age, male gender and living in a rural area were independently associated with seropositivity. Seropositivity rate was stable on the 2017-2020 period. Conclusion: The seroprevalence of infection by Borrelia species responsible for Lyme disease is high in Isere; this probably reduces the predictive positive value for Lyme disease of ELISA and WB IgG, suggesting that this serological test should not be performed for nonspecific symptoms.

Adaptive Immune Response Investigation in Lyme Borreliosis.

To diagnose Lyme Borreliosis, it is advised to use an enzyme-linked immunosorbent test to check for serum antibodies specific for Lyme and all tests with positive or ambiguous enzyme-linked immunosorbent assay (ELISA) results being confirmed by immunoblot. This method of measuring the humoral immunity in human fluids (e.g., by ELISA) has provided robust and reproducible results for decades and similar assays have been validated for monitoring of B cell immunity. These immunological tests that detect antibodies to Borrelia burgdorferi are useful in the diagnosis of Borreliosis on a routine basis. The variety of different Borrelia species and their different geographic distributions are the main reasons why standards and recommendations are not identical across all geographic regions of the world. In contrast to humoral immunity, the T cell reaction or cellular immunity to the Borrelia infection has not been well elucidated, but over time with more studies a novel T cell-based assay (EliSpot) has been developed and validated for the sensitive detection of antigen-specific T cell responses to B. burgdorferi. The EliSpot Lyme assay can be used to study the T cell response elicited by Borrelia infections, which bridges the gap between the ability to detect humoral immunity and cellular immunity in Lyme disease. In addition, detecting cellular immunity may be a helpful laboratory diagnostic test for Lyme disease, especially for seronegative Lyme patients. Since serodiagnostic methods of the Borrelia infection frequently provide false positive and negativeresults, this T cell-based diagnostic test (cellular assay) may help in confirming a Lyme diagnosis. Many clinical laboratories are convinced that the cellular assay is superior to the Western Blot assay in terms of sensitivity for detecting the underlying Borrelia infection. Research also suggests that there is a dissociation between the magnitude of the humoral and the T cell-mediated cellular immune responses in the Borrelia infection. Lastly, the data implies that the EliSpot Lyme assay may be helpful to identify Borrelia infected individuals when the serology-based diagnostic fails to do so. Here in this chapter the pairing of humoral and cellular immunity is employed to evaluate the adaptive response in patients.

Pulmonary and Liver Toxocariasis Mimicking Metastatic Tumors in a Patient with Colon Cancer.

Toxocariasis is an uncommon cause of multiple cavitary lung lesions and an ill-defined liver lesion. We herein report a patient with lung and liver toxocariasis, which mimicked metastatic lesions of colon cancer on 18F-FDG PET-CT and chest and abdominal CT performed for cancer staging after diagnosis of colon cancer. The patient was diagnosed with lung and liver toxocariasis by a positive enzyme-linked immunosorbent assay. Lung toxocariasis may occur as multiple cavitary lung lesions, and liver toxocariasis may appear as a solitary ill-defined nodule, which may be misdiagnosed as metastatic tumors. Clinicians should consider toxocariasis when multiple cavitary lung lesions and a solitary ill-defined focal liver lesion are detected, especially in a patient with cancer.

Seropositivity of Borrelia burgdorferi s.l. in Germany—an analysis across four German National Cohort (NAKO) study sites

Lyme borreliosis (LB) is caused by the transmission of Borrelia burgdorferi s.l. from ticks to humans. Climate affects tick abundance, and climate change is projected to promote shifts in abundance in Europe, potentially increasing human exposure. We analyzed serum samples collected between the years 2014–2019 from German National Cohort (NAKO) participants at four study sites (Augsburg, Berlin, Hanover, Münster) for immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies using an enzyme‐linked immunosorbent assay (ELISA) and line blot immunoassay as confirmatory test for positive and equivocal ELISA samples. We reported crude and weighted seropositivity proportions for local estimates. We used mixed model analysis to investigate associated factors, such as age, sex, migration background, or animal contacts. We determined the serostatus of 14,207 participants. The weighted seropositivity proportions were 3.4% (IgG) and 0.4% (IgM) in Augsburg, 4.1% (IgG) and 0.6% (IgM) in northern Berlin, 3.0% (IgG) and 0.9% (IgM) in Hanover, and 2.7% (IgG) and 0.6% (IgM) in Münster. We found higher odds for IgG seropositivity with advancing age (p < 0.001), among males compared to females (p < 0.001) and reduced odds among participants with migration background compared to those without (p = 0.001). We did not find evidence for an association between serostatus and depression, children within the household, or animal contact, respectively. We found low seropositivity proportions and indications of differences across the study locations, although between-group comparisons did not yield significant results. Comparisons to earlier research are subject to important limitations; however, our results indicate no major increases in seropositivity over time. Nevertheless, monitoring of seropositivity remains critical in light of potential climate-related Borrelia exposure.

Performance evaluation of heparin-induced platelet aggregation vs serotonin release assay.

Heparin-induced thrombocytopenia (HIT) is a rare but life-threatening condition that requires rapid diagnosis for proper management. Laboratory testing should only be performed on patients with intermediate- or high-risk pretest probability. The platelet factor 4 (PF4) enzyme-linked immunosorbent assay (ELISA) is the screening test that should be confirmed by higher specificity testing such as the heparin-induced platelet aggregation (HIPA) or the serotonin release assay (SRA). This study aims to evaluate the performance of the HIPA in comparison to the SRA, establish cutoffs of the PF4 ELISA to predict positivity for HIPA/SRA, and study the mortality rate between patients with suspected HIT confirmed as HIT positive vs negative. All positive PF4 ELISA cases with confirmatory HIPA and SRA testing were included. As the SRA was considered the gold standard, the HIPA performance was evaluated in comparison to SRA before and after the implementation of a new standardized interpretation guide in 2022. The mortality of these cases was also documented by chart reviews. In total, 232 cases with positive or indeterminate anti-PF4 IgG ELISA had confirmatory testing with HIPA and SRA. The sensitivity of the HIPA improved from 55.4% in 2018 to 2021 to 73.8% in 2022. The specificity remained similarly high in 2018 to 2021 vs 2022 (94.9% vs 87.5%). The negative predictive value (NPV) improved in 2022. The PF4 optical density cutoff to predict the positivity of SRA was 0.85 vs 1.47 to predict the positivity of HIPA but decreased to 0.83 when combining HIPA and/or SRA. There was no significant difference in mortality between patients with suspected HIT confirmed positive vs negative. Although the HIPA has a lower sensitivity than the SRA, the new standardized interpretation guide improved its sensitivity and NPV in 2022. Future improvements are needed to use the HIPA as a stand-alone confirmatory test with the goal to shorten hospital length of stay and expedite proper anticoagulation management.

3Ts Score, an Attempt for Less Testing in Thrombocytopenia Patients with Suspected Heparin Induced Thrombocytopenia (HIT): Retrospective Analysis in a University Hospital Setting

Background: Heparin-induced thrombocytopenia (HIT) is a prothrombotic and potentially fatal adverse drug reaction mediated by platelet-activating antibodies against multimolecular complexes of platelet factor 4 (PF4) and heparin. The 4Ts is a pretest scoring system for HIT that was developed to improve and standardize clinical diagnosis. The strength of the 4Ts score lies in the negative predictive value of a low pretest probability score. Those with a 4T score ≥4 is considered to have moderate to high probability of HIT and should undergo confirmatory laboratory test. Delays in treatment are associated with risk of thrombosis. Immediate cessation of heparin and initiation of a non-heparin anticoagulant is therefore standard of care. Method: This is a single institutional retrospective study. We reviewed the charts of 219 patients with thrombocytopenia with suspected HIT to evaluate the appropriateness of ordering the HIT testing based on the pretest probability of the 4Ts scoring system. All patients had enzyme linked immunosorbent assay (ELISA) test for HIT antibodies (the screening test). We studied tests that were sent from 03\16\2021 through 07\03\2023. The serotonin release assay (SRA) which is the confirmatory test for HIT was only sent for patients who had a positive ELISA test. 4T scores were calculated retrospectively using chart's information available to clinicians at the time of the HIT tests were sent. Results: Out of the 219 patients, 80(36.5%), 120(54.7%) and 19(8.6%) patients had a low, intermediate and high pretest probability respectively. The HIT ELISA test was positive in 33 (15.7%) patients and 196 (84.9%) patients had negative results. HIT ELISA had 100% and 93.5% sensitivity and specificity respectively while the positive and negative predicative values were 60% and 100% respectively. A positive SRA test was reported in 23 patients (10.5% of the total study population). Seventy-nine patients (36% of our total sample) scored 4 points which represents intermediate pretest probability. Out of these 79 patients only 6 (11.3%) patients had a positive ELISA test, and 5 (6.3%) patients had a positive SRA test. Aiming to minimize the HIT over testing we examined the increase in the cutoff point of the intermediate pretest probability from 4 points to 5 points which resulted in significant increase in the sensitivity and positive predictive value of the intermediate pretest probability (75.4% and 21% versus 39% and 12.9% respectively). However, the sensitivity dropped from 90% to 65%. The 4th part of 4Ts score gives points based on the probability of HIT versus other pathology as a cause of the thrombocytopenia. Most of the patients with suspected HIT will score one point out of the 4th part of 4Ts score which makes this part of the score is less helpful in distinguishing between patients with suspected HIT and will result in higher overall pretest probability and more testing. We studied the 3Ts score (the 4Ts scoring system after elimination of the 4th part) effect on the intermediate pretest probability. The cutoff points for the 3Ts score are 1-3, 4-5 and 6 for low, intermediate and high pretest probability respectively. The 3Ts score model resulted in significant increase in the specificity and the positive predictive value (76% and 21.7% versus 39.2% and 12.9% respectively) however the sensitivity dropped from 90% to 65%. The average turnaround time for HIT ELISA test and the SRA test was 2.3 days and 4.4 days respectively. Fifteen patients (21% out the patient had low pretest probability on the 4Ts score), 41 patients (59% of the patient who had an intermediate pretest probability on the 4Ts score) and 13 patients (18.8% of the patients who had high pretest probability on the 4Ts score) started on non-heparinoid anticoagulation meanwhile awaiting on the HIT testing result. Conclusion: Over testing of HIT is common secondary to underuse of 4Ts scoring system. Multicomponent educational interventions to increase the awareness and utility of the 4Ts score in addition to implantation of clinical decision support based on HIT computerized score will help to reduce unnecessary diagnostic testing of HIT in patients with low pretest probability. Increasing the cutoff point of the intermediate pretest probability or applying the 3Ts score model resulted in significant increase in the specificity and the positive predictive value of the 4Ts scoring system on expense of the scoring system sensitivity.

Efficiency of sandwich enzyme immunoassay for the diagnosis of larval echinococcus infection in cattle in the Republic of Azerbaijan

The purpose of the research is to develop a sandwich enzyme-linked immunosorbent assay (ELISA) for laboratory diagnosis of echinococcosis in animals. Materials and methods. The diagnostic efficiency of the ELISA test system developed by us against cystic echinococcus infection in cattle was studied by comparing the obtained results with the data of a postmortem examination of animal carcasses. The sera from 80 animals delivered to the slaughterhouse from farms of different regions of the Republic of Azerbaijan were tested. Results and discussion. A positive ELISA test result was obtained in 42 animals, which was 52.5% of the total number of the animals studied. The postmortem diagnosis was confirmed in 32 animals, which was 40.0%. The comparison of the ELISA diagnostic efficiency with the postmortem examination data was 68.75%. Fasciola species were found in the bile ducts in 7 animals with a positive ELISA test response to echinococcosis and a negative diagnosis in the postmortem examination, and Cysticercus tenuicollis was found in one animal.

Prevalence of asymptomatic strongyloidiasis co-infection in COVID-19 patients residing in endemic areas

BackgroundFatal forms of strongyloidiasis, hyperinfection syndrome (HS) and disseminated strongyloidiasis (DS), are caused by exaggerated autoinfection of the intestinal nematode, Strongyloides stercoralis (S. stercoralis). Corticosteroids, frequently administered to patients with severe COVID-19, can transform chronic asymptomatic strongyloidiasis into the above-mentioned fatal diseases. This study aimed to investigate the prevalence of strongyloidiasis in COVID-19 patients receiving corticosteroids in a hypoendemic region.MethodsThe present cross-sectional study enrolled 308 COVID-19 patients admitted to two hospitals in Ahvaz and Abadan in the southwest of Iran between 2020 and 2022. A real-time reverse transcription polymerase chain reaction (RT-PCR) test and chest computed tomography (CT) scan were employed to detect and monitor the disease’s severity in the patients, respectively. All patients were evaluated for IgG/IgM against S. stercoralis using Enzyme-linked immunosorbent assay (ELISA) test. Subsequently, individuals with a positive ELISA test were confirmed using parasitological methods, including direct smear and agar plate culture (APC).ResultsThe patients were between 15 and 94 years old, with a mean age of 57.99 ± 17.4 years. Of the 308 patients, 12 (3.9%) had a positive ELISA test, while 296 (96.1%) had negative results. Three of the 12 patients with a positive ELISA result died, and three failed to provide a stool sample. To this end, only six cases were examined parasitologically, in which S. stercoralis larvae were observed in five patients. Significant differences were found between S. stercoralis infection with sex (p = 0.037) and age (p = 0.027). Binary regression analysis revealed that strongyloidiasis was positively associated with sex (odds ratio [OR]: 5.137; 95% confidence interval [CI]: 1.107–23.847), age (OR: 5.647; 95% CI 1.216–26.218), and location (OR: 3.254; 95% CI: 0.864–12.257).ConclusionsOur findings suggest that screening for latent strongyloidiasis in COVID-19 patients in endemic areas using high-sensitivity diagnostic methods, particularly ELISA, before receiving suppressive drugs should be given more consideration.

Prevalence of Different Courses of Feline Leukaemia Virus Infection in Four European Countries.

Prevalence of progressive feline leukaemia virus (FeLV) infection is known to still be high in cats in Europe, especially in Southern Europe, but the prevalence of other outcomes of FeLV infection has not been determined in most countries. The present study aimed to investigate the prevalence of progressive, regressive, abortive, and focal infection in four European countries, two with a high (Italy, Portugal) and two with a low expected prevalence (Germany, France). Blood samples of 934 cats (Italy: 269; Portugal: 240; France: 107; Germany: 318) were evaluated for the p27 antigen, as well as anti-whole virus, anti-SU, and anti-p15E antibodies by enzyme-linked immunosorbent assay (ELISA) in serum and for proviral DNA by quantitative polymerase chain reaction (qPCR) in whole blood. Positive p27 antigen ELISA results were confirmed by reverse transcriptase-qPCR (RT-qPCR) detecting viral RNA in saliva swabs and/or blood. The outcome of FeLV infection was categorised as progressive (antigen-positive, provirus-positive), regressive (antigen-negative, provirus-positive), abortive (antigen- and provirus-negative, antibody-positive), and focal (antigen-positive, provirus-negative) infection. Overall FeLV prevalence was 21.2% in Italy, 20.4% in Portugal, 9.5% in Germany, and 9.3% in France. Prevalence of progressive, regressive, abortive, and focal infection in Italy was 7.8%, 4.5%, 6.3%, and 2.6%; in Portugal 3.8%, 8.3%, 6.7%, and 1.7%; in Germany 1.9%, 1.3%, 3.5%, and 2.8%; in France 1.9%, 3.7%, 2.8%, and 0.9%, respectively. In conclusion, overall FeLV prevalence is still very high, especially in Southern European countries. Therefore, testing, separation of infected cats, and vaccination are still important measures to reduce the risk of FeLV infection.

Associations between Johne’s disease and fertility in UK dairy herds

The objective of this observational study was to quantify associations between Mycobacterium avium subspecies paratuberculosis (MAP) antibody status and a variety of fertility outcomes, in UK dairy cattle. Longitudinal milk recording, fertility and MAP antibody enzyme-linked immunosorbent assay (ELISA) milk test data were collated retrospectively from 121,762 lactations in 78 herds. Datasets were structured into appropriate units to suit outcomes and enable temporal association between current and future MAP status, and fertility measures. Current MAP status was categorised according to most recent status within 180 days, with time-related future MAP status assigned based on MAP antibody ELISA milk test data for each cow. Multilevel multivariable logistic regression models were used to evaluate associations between MAP status and 21-day pregnancy and submission rate and conception risk. Posterior predictions and cross-validation techniques were used to assess model fit and check model building assumptions. A negative association was found between risk of insemination (Odds Ratio [OR], 0.78; 95% Credible Interval [CI], 0.66–0.92) and conception occurring (OR, 0.65; CI, 0.5–0.84) and transition from negative to non-negative MAP test status in the next 30–90 days. A positive association was observed between risk of insemination (OR, 1.34; CI, 1.16–1.52) and conception occurring (OR, 1.26; CI, 1.11–1.43) and transition from negative to non-negative MAP test status in the next 90–180 days. Current positive MAP test status was negatively and positively associated with insemination (OR, 0.59; CI, 0.49–0.70) and conception risk (OR, 1.12; CI, 0.96–1.30), respectively. Herd managers will have had access to test results, declaring cows with past recent or multiple positive MAP antibody ELISA results not to be bred, negatively influencing insemination risk. Overall, these results demonstrate the temporal association between a positive MAP antibody ELISA result and dairy cow fertility outcomes, with particular variability prior to a positive MAP antibody ELISA result.

ELISA F29 -A therapeutic efficacy biomarker in Chagas disease: Evaluation in pediatric patients treated with nifurtimox and followed for 4 years post-treatment.

Measurement of the success of antitrypanosomal treatment for Chagas disease is difficult, particularly in the chronic phase of the disease, because anti-Trypanosoma cruzi antibodies persist in serum for prolonged periods. We studied the effects of nifurtimox administered by two different treatment regimens on the T. cruzi calcium-binding flagellar protein F29 in children diagnosed with Chagas disease measured using an enzyme-linked immunosorbent assay (ELISA) technique (ELISA F29). In a phase 3, randomized, double-blind, parallel-group, historically controlled study (ClinicalTrials.gov NCT02625974), blood samples obtained from children diagnosed with Chagas disease and treated with nifurtimox for either 60 days or 30 days were analyzed using an ELISA with an F29 recombinant protein as the antigen, as well as conventional serological tests (recombinant ELISA and indirect hemagglutination assay). In an exploratory approach, serological response to nifurtimox treatment was evaluated for 4 years post-treatment. In both treatment groups, the number of patients with negative ELISA F29 values increased over the period of observation. The incidence rate of negative seroconversion using ELISA F29 was 22.94% (95% CI: 19.65%, 26.63%) in the 60-day treatment group and 21.64% (95% CI: 17.21%, 26.86%) in the 30-day treatment group. In the subpopulation of patients who tested seropositive for F29 before nifurtimox treatment, 88 patients (67.7%) in the 60-day regimen and 39 patients (59.1%) in the 30-day regimen were F29 seronegative at 4 years post-treatment. All patients who had a positive ELISA F29 test at baseline and seroconverted to negative measured by conventional serology reached seronegativity in ELISA F29 earlier than in conventional serology. The results demonstrate a serological response to treatment with nifurtimox measured by the ELISA F29 test in children diagnosed with Chagas disease. The F29-based ELISA can be considered a potential early marker of response to antitrypanosomal therapy for Chagas disease. ClinicalTrials.gov NCT02625974.

Evaluation of glutamic acid decarboxylase (GAD) 65 antibody detection methods for neurological and diabetic investigation in an Australian diagnostic laboratory

The role of anti-glutamic acid decarboxylase (GAD) 65 autoantibodies in autoimmune neurological conditions is evolving, but testing recommendations remain unchanged in Australia with GAD enzyme-linked immunosorbent assay (ELISA) and immunoblot as the only two Therapeutic Goods Administration approved testing methods available in Australia. Common practice is for use of ELISA in diagnosis of type 1 diabetes mellitus (T1DM) and use of immunoblot for diagnosis of GAD65-associated neurological disease. We observed a cohort of patients with negative immunoblot results and positive ELISA in the context of GAD-associated neurological disease without T1DM. In the absence of robust consensus guidelines on preferred testing modalities, we sought to determine if ELISA could have a superior role in the diagnosis of GAD-associated neurological disease when compared to immunoblot in this paper. We tested for anti-GAD65 autoantibodies on 55 patient samples, 40 samples requested for neurological disease and 15 type 1 diabetes samples with detectable anti-GAD65, using two testing platforms: Euroimmun anti-GAD enzyme-linked immunosorbent assay (ELISA) and. Euroimmun EuroLine immunoblot for paraneoplastic neurologic syndromes. These results were correlated against the clinical scenario. Positive ELISA results had a sensitivity of 100% and specificity of 91% for GAD65-related neurological disease. Immunoblot showed sensitivity of 43% and specificity of 76% for GAD65-related neurological disease. ELISA proved more sensitive and specific for GAD65-related neurological disease compared to immunoblot, raising questions about the role of this testing modality in neurological disease. We propose that ELISA should be used as a sole diagnostic method for all GAD65 antibody-related neurological disease over immunoblot. The presence of anti-GAD65 antibody on immunoblot is of doubtful clinical significance.

The Seroprevalence of Severe Fever with Thrombocytopenia Syndrome: An Epidemiological Study of Korean Veterinary Hospital Workers

Severe fever with thrombocytopenia syndrome (SFTS) is a zoonotic tick-borne infectious disease caused by the SFTS virus (SFTSV). Few studies have assessed SFTS seroprevalence among veterinary hospital staff and their awareness of SFTS. From January to May 2021, serum samples from 103 veterinary hospital staff were tested for SFTS using an enzyme-linked immunosorbent assay (ELISA), an immunofluorescence assay, and a 50% plaque reduction neutralization antibody test, which yielded positive results in four (3.9%), three (2.9%), and two (1.9%) participants, respectively. A questionnaire was used for an epidemiological investigation. ELISA positivity was higher among those who lacked awareness of possible animal-to-human SFTS transmission (p = 0.029). SFTS awareness was significantly lower among veterinary hospital staff than among the veterinarians (p < 0.001). Providing staff with training concerning standard precautions and the use of appropriate personal protective equipment is important.

Clinical outcomes for Clostridioides difficile associated diarrhea in inflammatory bowel disease patients versus non-IBD population: A retrospective cohort study.

Patients with inflammatory bowel disease (IBD) have a higher incidence of Clostridioides difficile infection (CDI). Previous studies have demonstrated negative clinical outcomes in IBD patients with CDI compared to patients without CDI. The clinical presentation of CDI is indistinguishable from IBD exacerbation, thus posing a frequent clinical dilemma on the role of Clostridioides infection in the testing, diagnosis, and treatment of these patients. To compare clinical outcomes of CDI in patients with IBD to those without IBD. Retrospective cohort of adult patients admitted to Rabin Medical Center Israel between the years 2014 and 2020 with a concurrent diagnosis of IBD and CDI. Matching 1:2 was performed between the IBD patients and the non-IBD population with respect to age and sex. Sixty-seven patients with IBD and 134 patients without IBD were included in the study. The groups' median age was 40.6 (interquartile range [IQR] of 29.8-68.9), with 45.8% male and 54.2% female. The non-IBD group had a higher Charlson score with 2 (IQR 0; 5) versus 0 (IQR 0; 4) in the IBD group (P value <.01). Patients with IBD had more exposure to systemic antibiotics, 71.1% versus 26.3% (P value <.01). In a multivariable analysis we found no difference in 90-day mortality and rate of relapse between the 2 study groups with an odds ratio of 1.709 (95% confidence interval 0.321-9.905) and odds ratio of 0.209 (95% confidence interval 0.055-1.513) respectively. In our cohort patients with IBD who present with diarrhea and concomitant CDI have similar rates of relapse and mortality compared with patients without IBD.

COVID-19 Vaccine-Associated Immune Thrombosis and Thrombocytopenia (VITT): Diagnostic Discrepancies and Global Implications.

Vaccine-induced immune thrombotic thrombocytopenia (VITT) has been reported in association with the coronavirus disease 2019 preventative adenovirus vector-based vaccines ChAdOx1 nCoV-19 (Oxford/AstraZeneca) and Ad26.COV2.S (Janssen/Johnson & Johnson) in hundreds of recipients across the globe. VITT is characterized by thrombosis, typically at unusual sites, low fibrinogen, and elevated plasma D-dimer, generally manifesting between 4 and 28 days following vaccination. Detection of anti-platelet factor antibodies using an enzyme-linked immunosorbent assay (ELISA) is often confirmatory. Although several similar principles subside in most diagnostic criteria for VITT, the presentation of a positive ELISA assay, use of expert hematology and neurology opinion, and exclusion of possible VITT cases outside the "standard" 4 to 28-day timeframe have contributed a lack of global standardization for defining VITT. Accordingly, the global and regional incidence of VITT differs according to the diagnostic pathway and case definition used. This has influenced the public perception of VITT's severity and the decision to use adenovirus vector-based vaccines for limiting severe acute respiratory syndrome coronavirus 2 infection. We hereby delineate the recognized pathogenic mechanisms, global incidence, discrepancies in diagnostic criteria, recommended treatments, and global implications to vaccine hesitancy from this coagulopathy.

385. Impact of the COVID-19 Pandemic First Wave on Clostridioides difficile Infection

Abstract Background Clostridioides difficile infection (CDI) is the leading cause of nosocomial diarrhea and a costly burden on the healthcare system. The COVID-19 pandemic brought enhanced infection control measures that could hypothetically decrease CDI transmission. Nonetheless, diarrhea secondary to COVID-19 and increased usage of broad-spectrum antibiotics could potentially increase testing for or frequency of CDI. We aimed to assess variations in CDI testing and frequency during the first surge of the COVID-19 pandemic in a tertiary community medical center in the Southern United States. Methods Records from adult patients were retrospectively reviewed at Princeton Baptist Medical Center, Birmingham, AL. Three groups spanning equal time periods were created based on the CDC COVID-19 rate curves for Alabama: PPG (pre-pandemic, 03/01/2020 to 05/31/2020), PG (pandemic, 06/01/2020 to 08/31/2020), and SCG (seasonal control, 06/01/2019 to 08/31/2019). We included patients ≥ 18 years old and excluded readmissions and follow-up visits. We determined the frequency, testing rates, and positivity rates for CDI in each group to assess their differences. Also, we measured the rate of coinfection between C. difficile and SARS-CoV-2. CDI cases were defined as positive toxin enzyme-linked immunosorbent assay (EIA) and glutamate dehydrogenase (GDH), or positivity of either in addition to positive nucleic acid amplification test (NAAT). Differences in frequencies and rates across groups were compared with Fisher exact test. Results Overall, 7,252 hospitalized patients and 29,671 outpatients were included (Figure 1). No outpatient CDI cases were detected. Outpatient testing rates were: PPG 3 (0.05%), PG 4 (0.05%), and SCG 9 (0.06%). Among inpatients, 3,912 (53.9%) were female with a mean ± SD age of 61.2 ± 17.5 years. Overall, CDI frequency, testing rates, and positivity rates did not vary significantly among all groups (Table 1). Among those tested, the only case of C.difficile/SARS-CoV-2 coinfection corresponded to PPG. Figure 1:Patient distributionTable 1:Frequency of CDI and COVID-19 infection in inpatients Conclusion There were no statistically significant differences in CDI frequency, or positivity rate between the pre-pandemic, pandemic, and seasonal control groups for inpatients. No CDI cases were detected in outpatients. This is likely due to a low testing rate in our population. Disclosures All Authors: No reported disclosures.

Combining Immunoassays to Identify Zika Virus Infection in Dengue-Endemic Areas.

Zika virus (ZIKV) is a mosquito-borne flavivirus that has recently emerged as a global health threat. The rise in ZIKV infections has driven an increased incidence of neonates born with microcephaly or other neurological malformations. Therefore, screening for ZIKV infection can considerably impact pregnant women, especially during the first trimester. The majority of ZIKV infections are mild or asymptomatic, and clinical diagnosis is inaccurate. Moreover, given the high level of cross-reactivity among flaviviruses, serological approaches to distinguish ZIKV from dengue virus (DENV) infections are complicated. We used the combination of DENV and ZIKV nonstructural protein 1 (NS1) IgG enzyme-linked immunosorbent assay (ELISA) and ZIKV NS1 blockade-of-binding (BOB) ELISA to test the convalescent sera of non-flavivirus, primary DENV, secondary DENV, and ZIKV infections. Our findings indicate that primary testing using a ZIKV NS1 IgG ELISA, the test of choice for large-scale ZIKV serosurvey studies, provided relatively high sensitivity. Moreover, the confirmation of positive ELISA results using the ZIKV NS1 BOB ELISA increased average specificity to 94.59% across serum samples. The combined use of two simple ELISAs for ZIKV serosurveys and the monitoring of ZIKV infection during pregnancy can elucidate the epidemiology, pathogenesis, and complications of ZIKV in DENV-endemic areas.