Clinical Significance of Indeterminate QuantiFERON-TB Gold Plus Assay Results in Hospitalized COVID-19 Patients with Severe Hyperinflammatory Syndrome

Performance of the QuantiFERON-TB Gold Plus (QFT-Plus) assay could be affected by conditions of immune dysregulation. Little is known about the reliability of QTF-Plus in COVID-19 patients. Our aim was to determine the prevalence and the factors related to an indeterminate QFT-Plus test in COVID-19 hospitalized patients, and to analyze its relationship with in-hospital mortality. A retrospective analysis of all hospitalized COVID-19 patients on whom a QTF-Plus assay was performed in a tertiary care public hospital during the first epidemic wave in Spain (March–April 2020). Out of a total of 96 patients included, 34 (35.4%) had an indeterminate result, in all cases due to a lack of response in the mitogen control. Factors related to COVID-19 severity, such as higher lactate dehydrogenase (LDH) (odds ratio [OR] 1.005 [95% confidence interval [CI] 1.002–1.008]) and previous administration of corticosteroids (OR 4.477 [95% CI 1.397–14.345]), were independent predictors for indeterminate QFT-Plus assay. Furthermore, indeterminate results were more frequent among COVID-19 patients who died during hospitalization (29.1% vs. 64.7%; p = 0.005). We conclude that QFT-Plus assay yielded an unexpected, high prevalence of indeterminate results in severe COVID-19 patients. Factors related to worse COVID-19 outcome, such as LDH, as well as corticosteroid use before the QFT-Plus assay, seem to be predictors for an indeterminate result. The role of an indeterminate QFT-Plus result in predicting COVID-19 severity and mortality should be evaluated.

100. Development and Implementation of a 2-Tier Testing Algorithm for Clostridioides difficile: An Evaluation of Outcomes on Patients with Indeterminate Results at 90 Days

Background There is no definitive gold standard for accurate diagnosis of Clostridioides difficile (C difficile) infection. There is ample evidence that relying on a molecular test such as Polymerase Chain Reaction (PCR) for diagnosis, can lead to over diagnosis and unnecessary treatment. Combined, multi-step algorithms have been proposed to improve specificity of testing. The challenge remains in interpreting discordant or indeterminate results. Additionally, the risk of hospitalization due to lack of treatment for indeterminate results remains unclear. Methods To improve C difficile testing, a new 2-tier algorithm was implemented in 2019 starting with PCR testing. An indeterminate result was defined as a sample with a positive PCR and a positive Glutamate Dehydrogenase (GDH)/negative toxin result or a positive PCR and a negative GDH/positive toxin result. Indeterminate results were classified by episode severity and number. Patient records were reviewed by the Antimicrobial Stewardship (AS) physician and pharmacist to determine true infection versus colonization. Treatment was given as per recent IDSA Guidelines. All patients with indeterminate results were followed for 90 days for development of infection or hospitalization due to C difficile. Adults with stool samples submitted for testing between 6/1/2019 and 12/31/2019 were included. A total of 169 specimens were reviewed: 75 were positive, 72 were indeterminate (4 excluded from final analysis) and 22 were negative. Results Using a 2-tier testing algorithm, 68 (41%) of all results were indeterminate. Our AS classified 47 (69%) of those as infection and 21 (31%) as colonization. Patients with indeterminate results who were treated had a low incidence (8.5%) of reinfection requiring hospitalization in the following 90 days. There were no hospitalizations in the untreated group. Of patients with an indeterminate result who were treated, 42 (89%) were categorized as an initial episode of C difficile infection. Conclusion Clinical correlation of indeterminate results is critical to algorithm interpretation. A combined approach with provider education, an electronic testing advisor, a 2-tier testing algorithm, daily monitoring and prescribing by the AS team resulted in favorable outcomes for patients with indeterminate results Disclosures All Authors: No reported disclosures

High rate of indeterminate results of the QuantiFERON-TB Gold in-tube test, third generation, in patients with systemic vasculitis

Objectives To describe the frequency of QuantiFERON-TB Gold in-tube test® (QFT-GIT) indeterminate results due to no response to phytohaemagglutinin A stimulation in the control tube in vasculitis patients prior to immunosuppressant therapy; and to compare it with other groups of patients. Methods This was a single-centre, retrospective study. Patients and controls were included between 1 January 2008 and 31 December 2015. We assessed the rate of indeterminate results of the QFT-GIT in 38 patients with systemic vasculitis prior to any corticosteroid or immunosuppressant therapy, compared with 40 non-vasculitis patients with biological inflammatory syndrome, and 310 non-immunosuppressed patients matched for gender and age. Results Indeterminate results due to no response to phytohaemagglutinin A were more frequent in vasculitis patients (21.1%) compared with non-vasculitis patients with biological inflammatory syndrome (7.5%) (Fisher's exact test: P = 0.11) and to anonymized controls (7%) (P = 0.009). Responses to phytohaemagglutinin A were significantly lower in vasculitis patients compared with other groups (Kruskal–Wallis test: P < 0.0001) and compared with non-vasculitis patients with biological inflammatory syndrome (P = 0.0015). The multivariable analysis identified as independent predictors of an indeterminate result of the QFT-GIT: the presence of systemic vasculitis (odds ratio 9.64 [1.14–81.3], P = 0.037) and a high neutrophil-to-lymphocyte ratio (odds ratio 1.70 [1.21–2.37], P = 0.002). One patient with an indeterminate result of QFT-GIT developed active tuberculosis after one year of corticosteroid therapy for giant cell arteritis. Conclusion Our results question the reliability of QFT-GIT to rule out latent tuberculosis in vasculitis patients at diagnosis, prior to immunosuppressant therapy.

The Two Couriers Problem

The problem of the two couriers is an old introductory problem from basic algebra first described by Augustus de Morgan in 1828 in his algebra textbook. The two couriers problem is interesting in that three of the possible answers are interrelated: zero, infinity, and undefined or indeterminate result. These three results relate to division from fractions; and more specifically, infinity and undefined or indeterminate result from division by zero. The aspect of division by zero makes the two couriers problem an ideal one for independent, objective examination within the mathematical framework of transmathematics—where division by zero is defined and has specific mathematical properties. The application to the original problem of the two couriers using transmathematics provides further insight into the answers of infinity, and undefined or indeterminate result, and a contradistinction between the answers provided in conventional mathematics versus transmathematics.

Screening for Lynch Syndrome by Immunohistochemistry of Mismatch Repair Proteins: Significance of Indeterminate Result and Correlation With Mutational Studies

Context.— Immunohistochemical expression of mismatch repair (MMR) protein is a well-accepted method for routine screening for Lynch syndrome with relatively high sensitivity and specificity. Occasionally, however, immunohistochemistry (IHC) can yield an equivocal result with poor reproducibility and the potential for misdiagnosis. Objective.— To determine the frequency and significance of indeterminate MMR IHC expression in patients routinely screened for Lynch syndrome and correlation with germline mutation studies. Design.— Semiquantitative scoring of MMR IHC was performed by image analysis in 479 cases, of which 380 were colorectal and 99 endometrial cancer. Scores of 10% or more, less than 10%, and 0% were used as cutoffs for retained, indeterminate, and loss of expression, respectively. Negative and indeterminate IHC results were confirmed by mutational studies. Results.— Four hundred eighteen of 479 cases (87.2%) were reported as retained expression, 45 (9.3%) as loss of expression, and 16 (3.3%) as indeterminate expression. Fifteen of 45 (33.3%) and 8 of 16 (50%) with loss and indeterminate expression, respectively, were found to have Lynch syndrome by germline studies. The overall frequency of Lynch syndrome in our patient population was 4.8% (23 of 479), and 34.7% of these (8 of 23) were associated with indeterminate IHC expression. In the indeterminate group, MLH1 germline mutation was the most frequent (6 of 13; 46.2%), followed by MSH6 (4 of 13; 30.7%). Conclusions.— Our findings provide further evidence that indeterminate IHC should be further investigated for possible MMR germline mutation. Guidelines for interpretation of MMR IHC and the establishment of more objective criteria for defining indeterminate results are important to improve the sensitivity and specificity of the IHC assay.

Evaluation of the new cobas® HCV genotyping test based on real-time PCRs of three different HCV genome regions

Background: Determination of the hepatitis C virus (HCV) genotype and discrimination between HCV subtypes 1a and 1b is still mandatory prior to anti-HCV treatment initiation. The aim of this study was to evaluate the performance of the recently introduced cobas Methods: The cobas Results: When accuracy was tested, panel members containing HCV subtypes 1a, 1b, and 3a were identified as expected; however, the new assay failed to identify low titer panel members containing HCV subtype 5a correctly. Of 183 clinical samples, 160 gave concordant results. For seven samples, an indeterminate result was reported with the cobas Conclusions: The cobas

Helminth Infection Increases the Probability of Indeterminate QuantiFERON Gold in Tube Results in Pregnant Women

Background.Approximately one-third of the world population is infected withM. tuberculosisand helminths (Kariminia et al. (2009), Walson et al. (2010)). Pregnancy and Helminth infection are known to suppress theTH1response (Kariminia et al. (2009), Elias et al. (2006)) on which the QuantiFERON Gold in Tube (QFT-GIT) assay, that measures the released IFN-γuponin vitrostimulation with mycobacterial antigens, relies on (Thomas et al. (2010)).Objective.To determine whether QFT-GIT indeterminate result is significantly associated with helminth infection or not.Methods.In this cross-sectional study, eighty-five pregnant mothers were screened for parasitic and LTBI using Kato-Katz and QFT-GIT test-respectively,Result.The prevalence of helminth infection in pregnant mothers was 23 (27%) of this 17 (20%) was due toSchistosoma mansoni. Among the total of 85 study participants 26.8% were QFT-GIT positive and 14 (17%) had indeterminate results. Three samples (21.4%) were randomly selected from the indeterminate QFT-GIT results and retested to check the reproducibility of the assay and remained indeterminate. QFT-GIT indeterminate result showed significant association with helminth infection.Conclusion.Helminth infections were significantly associated with indeterminate QFT-GIT results in pregnant mothers. Therefore further study is important to evaluate the possible effect of helminth infection by excluding the effect of pregnancy, as pregnancy also downregulates cellular immunity.