Improved Standardization of the Bio-Rad Platelia Aspergillus Galactomannan Antigen Sandwich Enzyme Immunoassay Using the DS2 (Dynex) Enzyme-Linked Immunosorbent Assay (ELISA) Processing System

The galactomannan enzyme immunoassay (GM-EIA) is widely utilized for the diagnosis of invasive aspergillosis (IA). There is inconsistent reproducibility of results between centers when the assay is processed manually. Automation of EIAs can reduce variation. This study investigated the semiautomation of the GM-EIA on the DS2 (Dynex) platform in the following three stages: (i) DS2 GM-EIA method validation with experimental samples, (ii) DS2 retesting of case-defined clinical samples, and (iii) a 12-month audit of DS2 GM-EIA performance. In stage i, Bland-Altman analysis demonstrated a reduced variance between optical density index (ODI) values for samples processed on two DS2 platforms (mean difference, −0.02; limits of agreement [LOA], −0.19 to 0.14) compared with the variance between samples processed manually and on a DS2 platform (mean difference, 0.02; LOA, −0.25 to 0.3). In stage ii, 100% (14/14 samples) qualitative agreement was observed for serum samples from patients with IA, with no significant change in the ODI values when samples were processed on the DS2 platform. A significant decrease in ODI values was observed for control serum samples on the DS2 platform (difference, 0.01; P = 0.042). In stage iii, a significant reduction in the frequency of equivocal results, from 5.56% (136/2,443 samples) to 1.56% (15/961 samples), was observed after DS2 automation (difference, 4.0%; 95% confidence interval [CI], 2.7 to 5.2%; P < 0.01), with an equivalent increase in negative results. This study demonstrates that GM-EIA automation may reduce intersite variability. Automation does not have an impact on the repeatability of truly positive results but contributes to a reduction in false-positive (equivocal) GM-EIA results, reducing the need to retest a significant proportion of samples.     

Detection of galactomannan antigenemia in patients receiving piperacillin-tazobactam and correlations between in vitro, in vivo, and clinical properties of the drug-antigen interaction

Recent case reports describe patients receiving piperacillin-tazobactam who were found to have circulating galactomannan detected by the double sandwich enzyme-linked immunosorbent assay (ELISA) system, leading to the false presumption of invasive aspergillosis. Since this property of piperacillin-tazobactam and galactomannan ELISA is not well understood, we investigated the in vitro, in vivo, and clinical properties of this interaction. Among the 12 reconstituted antibiotics representing four classes of antibacterial compounds that are commonly used in immunocompromised patients, piperacillin-tazobactam expressed a distinctively high level of galactomannan antigen in vitro (P = 0.001). After intravenous infusion of piperacillin-tazobactam into rabbits, the serum galactomannan index (GMI) in vivo changed significantly (P = 0.0007) from a preinfusion mean baseline value of 0.27 to a mean GMI of 0.83 by 30 min to slowly decline to a mean GMI of 0.44 24 h later. Repeated administration of piperacillin-tazobactam over 7 days resulted in accumulation of circulating galactomannan to a mean peak GMI of 1.31 and a nadir of 0.53. Further studies revealed that the antigen reached a steady state by the third day of administration of piperacillin-tazobactam. Twenty-six hospitalized patients with no evidence of invasive aspergillosis who were receiving antibiotics and ten healthy blood bank donors were studied for expression of circulating galactomannan. Patients (n = 13) receiving piperacillin-tazobactam had significantly greater mean serum GMI values (0.74 +/- 0.14) compared to patients (n = 13) receiving other antibiotics (0.14 +/- 0.08) and compared to healthy blood bank donors (0.14 +/- 0.06) (P < 0.001). Five (38.5%) of thirteen patients receiving piperacillin-tazobactam had serum GMI values > 0.5 compared to none of thirteen subjects receiving other antibiotics (P = 0.039) and to none of ten healthy blood bank donors (P = 0.046). These data demonstrate that among antibiotics that are commonly used in immunocompromised patients, only piperacillin-tazobactam contains significant amounts of galactomannan antigen in vitro, that in animals receiving piperacillin-tazobactam circulating galactomannan antigen accumulates in vivo to significantly increased and sustained levels, and that some but not all patients receiving this antibiotic will demonstrate circulating galactomannan above the threshold considered positive for invasive aspergillosis by the recently licensed double sandwich ELISA.     

Lyme disease overdiagnosis in a large healthcare system: a population-based,retrospective study

ObjectivesTo evaluate the impact of false-positive IgM immunoblots on Lyme disease treatment and case reporting in a large healthcare system.MethodsWe obtained the results of all Lyme disease serological tests ordered at U.S. Air Force healthcare facilities in the USA between January 2013 and December 2017. We conducted chart reviews to adjudicate positive IgM immunoblots (from two-tier and independent testing) as true positives or false positives using established criteria, and we assessed whether these cases were reported to the U.S. Department of Defense surveillance system.ResultsOf the 18 410 serum tests (17 058 immunoassays and 1352 immunoblots) performed on 15 928 unique individuals, 249/1352 (18.4%) IgM immunoblots were positive. After excluding repeat tests, insufficiently documented cases, and participants with a history of Lyme disease, 212 positive IgM immunoblot cases were assessed. A total of 113/212 (53.3%) were determined to be false positives. Antibiotics were prescribed for Lyme disease for 97/99 (98.0%) participants with a true-positive test and 91/113 (80.5%) participants with a false-positive test. The number of false-positive cases reported to the surveillance system was identical to the number of unreported true-positive cases (n = 44).ConclusionsLyme disease serological tests were overused in a large healthcare system, and positive results were frequently misinterpreted, leading to misdiagnosis and widespread antibiotic misuse. Underreporting of true-positive cases was offset by overreporting of false-positive cases, suggesting that the discrepancy between the reported incidence and true incidence of Lyme disease may not be as significant as previously assumed.     

Using routine blood parameters to anticipate clinical outcomes in invasive aspergillosis

ObjectiveIn invasive aspergillosis (IA), monitoring response to antifungal treatment is challenging. We aimed to explore if routine blood parameters help to anticipate outcomes following IA.MethodsPost hoc secondary analysis of two multicenter randomized trials was performed. The Global Comparative Aspergillosis Study (GCA, n = 123) and the Combination Antifungal Study (CAS, n = 251) constituted the discovery and validation cohorts respectively. The outcome measures were response to treatment and survival to 12 weeks. Interval platelet, galactomannan index (GMI) and C-reactive protein (CRP) levels prior and during antifungal treatment were analysed using logistic regression, Kaplan–Meier survival and receiver operating characteristic (ROC) analyses.ResultsThe 12-week survival was 70.7% and 63.7% for the GCA and CAS cohorts respectively. In the GCA cohort, every 10 × 10⁹/L platelet count increase at week 2 and 4 improved 12-week survival odds by 6–18% (odds ratio (OR) 1.06–1.18, 95% confidence interval (CI) 1.02–1.33). Survival odds also improved 13% with every 10 mg/dL CRP drop at week 1 and 2 (OR 0.87, 95% CI 0.78−0.97). In the CAS cohort, week 2 platelet count was also associated with 12-week survival with 10% improved odds for every 10 × 10⁹/L platelet increase (OR, 1.10, 95% CI 1.04−1.15). A GMI drop of 0.1 unit was additionally found to increase the odds of treatment response by 3% at the baseline of week 0 (OR 0.97, 95% CI 0.95−0.99). Week 2 platelet and CRP levels performed better than GMI on ROC analyses for survival (area under ROC curve 0.76, 0.87 and 0.67 respectively). A baseline platelet count higher than 30 × 10⁹/L clearly identified patients with >75% survival probability.ConclusionsHigher serial platelets were associated with overall survival while GMI trends were linked to IA treatment response. Routine and simple laboratory indices may aid follow-up of response in IA patients.     

Reproducibility of low galactomannan enzyme immunoassay index values tested in multiple laboratories

The Platelia galactomannan enzyme immunoassay is a commercially available nonculture method for diagnosing invasive aspergillosis. Recently, steps have been taken to improve sensitivity; specifically, a low (0.5 to 0.7) galactomannan index (GMI) value to determine positivity has been validated by multiple groups. We evaluated the intra-assay and interassay reproducibility at low index levels using three different kit lots on three different days in three different microbiology laboratories. Clinical and spiked sera were blinded and sent with galactomannan enzyme immunoassay (EIA) kits to the participating laboratories. We also prospectively collected data on all galactomannan EIAs performed between 1 September 2003 and 21 July 2004 at the University of Washington Medical Center microbiology laboratory to assess reproducibility of clinical samples analyzed in "real time." From the multilaboratory study, a total of 836 results were available for evaluation. Reproducibility was excellent between laboratories and on different days. Significant variability was seen between runs/lots, which may in part be associated with different threshold control values in different kits. Among the 1,410 clinical samples that were prospectively analyzed, 168 (90%) were confirmed to be positive on repeat testing (GMI, > or =0.5). Among the 19 (10.2%) initially positive samples not confirmed on repeat testing, the majority had a GMI at the threshold of the assay (between 0.5 and 0.7). Our findings suggest that the Platelia galactomannan immunoassay has good reproducibility. However, changes in GMI levels when different kit lots are used, and single samples with low-positive (GMI of 0.5 to 0.7) indices, should be interpreted with caution.     

Discordant noninvasive prenatal testing and cytogenetic results: a study of 109 consecutive cases

PurposeRecent published studies have demonstrated the incremental value of the use of cell-free DNA for noninvasive prenatal testing with 100% sensitivity for trisomies 21 and 18 and a specificity of ≥99.7% for both. Data presented by two independent groups suggesting positive results by noninvasive prenatal testing were not confirmed by cytogenetic studies.MethodsConcordance of results among cases with noninvasive prenatal testing referred for cytogenetic prenatal and/or postnatal studies by karyotyping, fluorescence in situ hybridization, and/or oligo–single-nucleotide polymorphism microarray was evaluated for 109 consecutive specimens.ResultsCytogenetic results were positive for trisomy 21 in 38 of the 41 noninvasive prenatal testing–positive cases (true-positive rate: 93%) and for trisomy 18 in 16 of the 25 noninvasive prenatal testing–positive cases (true-positive rate: 64%). The true-positive rate was only 44% (7/16 cases) for trisomy 13 and 38% (6/16 cases) for sex chromosome aneuploidy.ConclusionThese findings raise concerns about the limitations of noninvasive prenatal testing and the need for analysis of a larger number of false-positive cases to provide true positive predictive values for noninvasive testing and to search for potential biological or technical causes. Our data suggest the need for a careful interpretation of noninvasive prenatal testing results and cautious transmission of the same to providers and patients.     

Real-world performance of the new US HIV testing algorithm in medical settings

BackgroundOur medical center laboratory recently adapted its 24/7, two-hourly testing program to use an ARCHITECT-Multispot-viral load (AR-MS-VL) algorithm in place of a previous rapid test-immunofluorescence (RT-IF) algorithm.ObjectivesWe evaluated screening test performance, acute case detection, turnaround time and ability to resolve HIV status under the new algorithm.Study designWe considered consecutive HIV tests from January to November 2015. AR-MS-VL results at Zuckerberg San Francisco General Hospital and Trauma Center (ZSFG) were compared with RT-IF results at ZSFG and also with AR-MS-VL results in the recently completed CDC Screening Targeted Populations to Interrupt On-going Chains of HIV Transmission with Enhanced Partner Notification (STOP) Study for targeted testing of MSM at publicly funded testing sites in San Francisco.ResultsAmong 21,985 HIV tests performed at ZSFG, 16,467 were tested by RT-IF and 5518 by AR-MS-VL. There were 321 HIV infections detected, of which 274 (84%) were known HIV+ cases, and 47 were newly identified HIV infections. Considering only patients of HIV-negative or -unknown status, prevalence was 0.22%. Under the AR-MS-VL algorithm, turnaround times for screening results and full algorithm results were 3 and 21 h; status-unresolved cases were reduced (from 47% to 22%) compared with the RT-IF algorithm. The positive predictive value (PPV) of a new-positive AR screening test was low (0.44) at ZSFG, where no acute infections were detected. At STOP Study sites where HIV prevalence was higher and acute infection was more common, the AR PPV was higher (0.93). All 24 false-positive AR screening tests at ZSFG had a signal/cutoff (S/CO) ratio of <15 and all 88 true-positive tests had S/CO ratio >15. Of 62 acute infections in the STOP Study, 23 (37%) had an S/CO < 15.DiscussionAn AR-MS-VL algorithm is feasible and can return rapid results in a large medical center. In this setting, reactive 4th generation assay tests that are negative for HIV antibodies are typically false-positive with low S/CO ratios.     

Intravenous immunoglobulin treatment for patients with severe COVID-19: a retrospective multicentre study

ObjectivesIntravenous immunoglobulin (IVIG) is commonly used to treat severe COVID-19, although the clinical outcome of such treatment remains unclear. This study evaluated the effectiveness of IVIG treatment in severe COVID-19 patients.MethodsThis retrospective multicentre study evaluated 28-day mortality in severe COVID-19 patients with or without IVIG treatment. Each patient treated with IVIG was matched with one untreated patient. Logistic regression and inverse probability weighting (IPW) were used to control confounding factors.ResultsThe study included 850 patients (421 IVIG-treated patients and 429 non-IVIG-treated patients). After matching, 406 patients per group remained. No significant difference in 28-day mortality was observed after IPW analysis (average treatment effect (ATE) = 0.008, 95% CI –0.081 to 0.097, p 0.863). There were no significant differences between the IVIG group and non-IVIG group for acute respiratory distress syndrome, diffuse intravascular coagulation, myocardial injury, acute hepatic injury, shock, acute kidney injury, non-invasive mechanical ventilation, invasive mechanical ventilation, continuous renal replacement therapy and extracorporeal membrane oxygenation except for prone position ventilation (ATE = –0.022, 95% CI –0.041 to –0.002, p 0.028).DiscussionIVIG treatment was not associated with significant changes in 28-day mortality in severe COVID-19 patients. The effectiveness of IVIG in treating patients with severe COVID-19 needs to be further investigated through future studies.     

Long-Term Stability at ?20°C of Aspergillus Galactomannan in Serum and Bronchoalveolar Lavage Specimens

Research to develop and validate novel methods for diagnosis of aspergillosis based on detection of galactomannan requires the use of clinical specimens that have been stored frozen. Data indicating that galactomannan remains stable when frozen are scant. The objective of this study was to determine the stability of galactomannan in clinical specimens stored at −20°C that were positive in the Platelia Aspergillus enzyme immunoassay when initially tested. Prospective real-time testing of serum and bronchoalveolar lavage (BAL) fluid pools from positive and negative patient specimens showed no decline in galactomannan index (GMI) over 11 months at −20°C and no development of positive reactions in the negative-control pool. Retrospective testing of positive specimens that had been stored at −20°C for 5 years showed that 28 of 30 serum (n = 15) or BAL (n = 15) specimens remained positive. These findings support the use of frozen serum or BAL specimens stored for at least 5 years in evaluation of diagnostic tests based on detection of galactomannan.     

The detection,treatment of parvovirus B19 infection induced anemia in solid organ transplants: A case series and literature review of 194 patients

BackgroundThere are no optimal diagnostic, treatment and post-infection surveillance strategies for parvovirus B19 infection in solid organ transplantation (SOT) recipients.MethodsWe conducted a retrospective review of all PVB19 infected cases confirmed by qPCR among SOT recipients at our institution over a 3-year period and reviewed the literature from 1990 to 2021.ResultsEight kidney and two heart transplant patients with refractory anemia had PVB19 infection. The viral DNA load in peripheral blood ranged from 2.62 × 10² to 8.31 × 10⁶ copies/mL. Two patients with the lowest PVB19 DNA load only reduced the use of immunosuppressants and anemia was relieved. Eight received intravenous immunoglobulin (IVIG) (ranging from 0.25 to 0.5 g/kg/day). The median time to anemia improvement (hemoglobulin > 100 g/L) was 16 days (8–70 days) after treatment. One patient had a PVB19 relapse and viral DNA load > 1.00 × 10⁸ copies/mL at diagnosis. A total of 86 studies involving 194 SOTs were screened from the literature, and the most common symptom was anemia and low reticulocyte count. PVB19 DNA was detected in all cases. Of that, 91.4% of cases received IVIG, 53.8% received IVIG and immunosuppression reduction, 6.5% of cases showed reduced immunosuppression without IVIG, and 2.1% did not receive any special treatment. The recurrence rate was 17.5%.ConclusionPVB19 infection is a cause of anemia after SOT, and treatment mainly relies on IVIG and/or immunosuppression reduction.     

Screening and exclusion of Zika virus infection in travellers by an NS1-based ELISA and qRT-PCR

ObjectivesZika virus (ZIKV) infection during pregnancy may cause neurological abnormalities in the foetus, and therefore fast and accurate laboratory assays are critical for rapid diagnosis. ELISA based on ZIKV NS1 protein has been developed and shown to be sensitive and highly specific; however, its negative and positive predictive values have not been tested. In this study we evaluated the ability of the NS1-based ELISA to exclude ZIKV infection and serve as a first-line screening tool for travellers.MethodsWe tested samples obtained during the peak of ZIKV infection from 1188 symptomatic and asymptomatic Israeli travellers using NS1-based IgG and IgM ELISA, real-time RT-PCR analysis and ZIKV neutralization. The Kaplan–Maier method was used to evaluate the duration of ZIKV RNA in whole blood and urine samples.ResultsNS1-based ELISA identified 20 true-positive, five false-positive and four false-negative cases, resulting in sensitivity and specificity of 83.3% (95%CI: 62–94%) and 97.5% (95%CI: 94–99%) respectively, and positive and negative predictive values of 80% (95%CI: 59–92%) and 98% (95%CI: 95–99%) respectively. Based on 14 RT-PCR-positive cases, median time to detect ZIKV RNA in whole blood was 17.5 days (range 5–58 days) and in urine 10 days (range 5–26 days).ConclusionsThe NS1-based ELISA and RT-PCR in whole blood are highly reliable for identification of ZIKV-negative and -positive cases, respectively. Combination of both assays minimizes the risk of false-negative results, and thus allows the exclusion of ZIKV infection in travellers returning from ZIKV-endemic countries, including those who are pregnant or wish for preconception screening.     

Pulmonary vascular resistance as a potential marker of reactive pulmonary hypertension reduction following sildenafil therapy in patients disqualified from orthotopic heart transplantation

PurposeWe sought to determine the predictors of restoration of heart transplantation (HTx) candidacy in patients with systolic heart failure (HF) and reactive fixed pulmonary hypertension (RFPH) defined as pulmonary vascular resistance (PVR) > 2.5 Wood units (WU), transpulmonary gradient (TPG) > 12 mmHg or ≤2.5 WU with systolic arterial pressure ≤85 mmHg during vasoreactivity test, following sildenafil therapy.Material and methodsBetween 2007 and 2018 1136 patients were evaluated at our department as candidates for HTx. Thirty-five of them, who presented with systolic HF and were not eligible for HTx due to RFPH, were included in the study (31 men aged 55.1 ± 7.4 years). In all the patients sildenafil was introduced and up-titrated to a maximal tolerated dose in addition to optimal medical therapy. Patients were assessed at 3–6 months intervals.ResultsDuring median 11 months (interquartile range 6–18 months) reduction of RFPH enabling qualification for HTx was observed in 62.9% patients. Higher baseline PVR (OR 0.32; 95% CI (0.14–0.74) p < 0.001), pulmonary artery systolic pressure (PASP) (OR 0.94, 95% CI (0.88–0.99) p = 0.05), mean artery pulmonary pressure (mPAP) (OR 0.87, 95% CI (0.77–0.98) p = 0.02) and TPG (OR 082, 95% CI (0.70–0.96) p = 0.003) were negative predictors of RFPH reduction with sildenafil therapy. In multivariable analysis, lower PVR (p = 0.02) was identified as an independent predictor of RFPH reduction following sildenafil therapy.ConclusionSildenafil therapy can support PH reduction in systolic HF patients uneligible for HTx due to RFPH. Lower baseline PVR was identified as an independent predictor of PH reversibility with sildenafil enabling restoration of HTx candidacy.     

Intravenous immunoglobulins reduce skin thickness in systemic sclerosis: evidence from Systematic Literature Review and from real life experience

IntroductionIntravenous immunoglobulins (IVIG) are a new therapeutic approach in systemic sclerosis SSc. An immunomodulatory and antifibrotic activity has been postulated. IVIG are generally well tolerated and have only rare side effects. Our retrospective study focused its attention on SSc, an autoimmune connective tissue disease, characterized by several complications which has a significant impact on patient's quality of life. The pathophysiology comprises fibrotic, vascular and immunological aspects.AimThe aim of this study was to verify the effectiveness of IVIG on SSc skin involvement. Moreover, a systematic review of the literature (SLR) of the results obtained to date on the use of Intravenous immunoglobulin (IVIG) in SSc has been also performed.Patients and methodsThe data of 24 patients (21 women, 3 male) with refractory diffuse SSc skin involvement were evaluated (mean age was 52.13 years). IVIG infusion at a dosage of 2 g/Kg body weight for 4 consecutive days/month, was started between 2002 and 2019. Skin involvement was evaluated with the modified Rodnan Skin Score (mRSS) before therapy and then again after 6 and 12 months. To perform the SLR, the PubMed, Medline, Embase, and Web of Science database were searched from 1990 to 2020 (keywords: IVIG, systemic sclerosis). Three assessors (E.A., C.B. & M.M.C) identified the criteria to scan all papers.ResultsFrom the total SLR (106 results), 17 papers were identified after the separation of the clinical cases from the studies (total number of treated patients 183). The studies were classified according to the organ involvement considered in each study, as well as the prescribed dose (high or low doses), and the therapeutic regimens. In the selected papers, the organs mainly involved were the skin, the gastrointestinal, the joint and the cardiovascular systems. Only in one case, plasmapheresis was associated to IVIG. All papers reported significant reduction of the skin involvement, although generally the strength of the works was limited the lack of control cases or by the low number of patients involved.From the real life experience, a statistically significant reduction of mRSS was obtained at 6 months follow-up (average value of −6.61 ± 5.2, p < 0.001), and it was further maintained with a significant stabilization after 12-months (−11.45 ± 9.63, p < 0.002).DiscussionThis SLR and the data of the retrospective study suggest that IVIG may improve skin involvement reducing mRSS in particular in those patients that were refractory to other standard of care therapies and represents a therapeutic option in patients with concomitant myositis. The literature review revealed encouraging perspectives on the use of this therapy, given the effectiveness found in the selected works.     

Occurrence and kinetics of false-positive Aspergillus galactomannan test results following treatment with beta-lactam antibiotics in patients with hematological disorders

Several reports have described a high rate of false-positive Aspergillus galactomannan (GM) test results for patients treated with piperacillin-tazobactam. In this retrospective study, we first examined the relationships between intravenous administration of three beta-lactam antibiotics and the occurrence of false-positive GM test results in hematology patients. We then estimated the kinetics of clearance of GM after the cessation of treatment. Sequential serum samples from 69 patients that had received beta-lactams were analyzed by using a Platelia Aspergillus test. A significant association was found between GM positivity (>/=0.5) and the administration of beta-lactams (P < 0.0001). The direct role of beta-lactams in patients' serum positivity was assessed by testing 39 batches of beta-lactams, of which 27 were positive for GM. None of the latter were positive according to a fungus- and Aspergillus-specific PCR. The kinetics of the decrease of GM was analyzed on sequential serum samples obtained after treatment. By use of a nonlinear regression model, the average time to negative antigen was assessed to be 5.5 days (95% confidence interval [CI], 4.1 to [7.0]), with a half-life of elimination of GM of 2.4 days (95% CI, 1.8 to 3.0). This study confirms that the administration of beta-lactams containing GM is responsible for false-positive diagnostic results, even up to 5 days after the cessation of treatment.     

High-volume culture and quantitative real-time PCR for the detection of Aspergillus in sputum

ObjectivesSputum culture is an insensitive method for the diagnosis of pulmonary aspergillosis. Growth of the organism allows identification of the causative species and susceptibility testing, both of which can inform treatment choices. The current practice is to culture an aliquot of diluted sputum. We assessed the value of culturing large volumes of unprocessed sputum, a method that we have termed high-volume culture (HVC).MethodsSpecimens were processed by conventional culture (using an aliquot of homogenized, diluted sputum on Sabouraud agar at 37°C and 45°C for up to 5 days) and HVC (using undiluted sputum on Sabouraud agar at 30°C for up to 14 days). A separate specimen was tested by quantitative real-time PCR. Antifungal susceptibility testing was performed by the EUCAST standard.ResultsWe obtained sputum specimens from 229 individuals with the following conditions: chronic pulmonary aspergillosis (66.8%, 153/229), allergic bronchopulmonary aspergillosis (25.3%, 58/229) and Aspergillus bronchitis (7.9%, 18/229). Individuals with invasive pulmonary aspergillosis were not included. The positivity rate of conventional culture was 15.7% (36/229, 95% CI 11.6%–21.0%) and that of HVC was 54.2% (124/229, 95% CI 47.7%–60.5%) (p < 0.001). The higher positivity rate of HVC was demonstrated regardless of administration of antifungal treatment. Quantitive real-time PCR had an overall positivity rate of 49.2% (65/132, 95% CI 40.9%–57.7%), comparable to that of HVC.ConclusionDetection of Aspergillus spp. in sputum is greatly enhanced by HVC. HVC allows for detection of azole-resistant isolates that would have been missed by conventional culture. This method can be performed in any microbiology laboratory without the need for additional equipment.     

Reduction in False-Positive Aspergillus Serum Galactomannan Enzyme Immunoassay Results Associated with Use of Piperacillin-Tazobactam in the United States

Piperacillin-tazobactam (PTZ) is known to cause false-positive results in the Platelia Aspergillus enzyme-linked immunoassay (EIA), due to contamination with galactomannan (GM). We tested 32 lots of PTZ and 27 serum specimens from patients receiving PTZ. GM was not detected in the lots of PTZ; one serum specimen (3.7%) was positive. PTZ formulations commonly used in the United States today appear to be a rare cause for false-positive GM results.     

The impact of the updated EORTC/MSG criteria on the classification of hematological patients with suspected invasive pulmonary aspergillosis

ObjectivesOur aim was to evaluate the effect of the updated European Organization for Research and Treatment of Cancer (EORTC) and Mycoses Study Group 2019 definitions for invasive pulmonary aspergillosis (IPA) on patient classification and the related all-cause 12-week mortality.MethodsIn this retrospective cohort study from our tertiary care centre, we reclassified patients with haematological malignancy who underwent bronchoalveolar lavage between 2014 and 2019 for suspected IPA using the novel EORTC 2019 criteria. We performed receiver operating characteristic curve analysis to define the optimal cut-off for positive PCR and galactomannan and present survival analyses and their possible association with these diagnostic criteria through post hoc comparisons with log rank and Cox regression.ResultsFrom 323 episodes of suspected IPA in 282 patients, 73 were reclassified: 31 (42.5%) from possible to probable IPA, 5 (6.8%) from EORTC criteria not met to probable IPA, and 37 (50.7%) from EORTC criteria not met to possible IPA. Probable IPA increased therefore 11.1% (64/323, 19.8% to 100/323, 30.9%), mostly due to positive PCR (31/36, 86.1%). There was no difference in mortality between newly defined possible and probable IPA (log rank p = 0.950). Mortality was higher in probable cases with lower cycle thresholds (Ct values) versus higher Ct values (p = 0.004). Receiver operating characteristic curve analysis showed an optimal Ct value cut-off of 36.8 with a sensitivity of 75% (95% CI 64.9%–85.1%) and a specificity of 61.7% (95% CI 53.5–69.9) for 12-week mortality.DiscussionThe new EORTC criteria led to 11.1% more probable IPA diagnoses, mostly due to Aspergillus PCR. Restricting positive PCR to below a certain threshold might improve the discrimination of the new EORTC IPA categories for mortality.     

Reduction in newborn screening metabolic false-positive results following a new collection protocol

PurposeNewborn screening includes testing for many metabolic diseases. False-positive results are higher among neonatal intensive care unit infants, resulting in increased confirmatory testing and family stress. Amino acid administration as a component of total parenteral nutrition is commonly used in the neonatal intensive care unit and suggested as a factor increasing false-positive results. The purpose of this study was to investigate the impact of a new sample collection protocol on false-positive results.MethodsThis was a 2-year retrospective cohort study. Infants were grouped by birth year into pre- and postprotocol implementation and stratified by birth weight category. In 2010, newborn screening samples were collected from all infants regardless of total parenteral nutrition administration. In 2011, the protocol was changed, and total parenteral nutrition was replaced with 10% dextrose in water (D10W) for 3 h before sample collection.ResultsData from 539 neonatal intensive care unit admissions were reviewed. The new protocol reduced false-positive results for each birth weight group by at least 50% and overall by 74% (P = 0.008). The odds of having a false-positive result preintervention were 3.87 times higher than postintervention. The protocol reduced estimated costs by >80%.ConclusionA protocol interrupting total parenteral nutrition for 3 h before newborn screening collection resulted in a 74% reduction in false-positive results in a neonatal intensive care unit.Genet Med16 6, 477–483.     

Rapid bacterial antigen detection is not clinically useful.

Latex agglutination (LA) of capsular polysaccharide bacterial antigen is a frequently performed laboratory procedure, but its use is controversial. To assess the clinical utility of this test, we reviewed all LA tests performed over a 10-month period at two sites, a major university-based referral center and a private specialty pediatric hospital. Samples were assayed either individually or as a panel for the group B streptococcus, Streptococcus pneumoniae, Haemophilus influenzae, and three sets of Neisseria meningitidis serogroups (A and Y, C and W135, and B and Escherichia coli K1). Of 5,169 assays performed on 1,268 clinical samples (786 urine and 478 cerebrospinal fluid, 3 pleural fluid, and 1 synovial fluid sample), 57 (1.1%) were positive, including 1.7% of urine and 0.3% of cerebrospinal fluid samples. All LA true-positive cerebrospinal fluid samples showed the causative microorganisms by Gram stain. Detailed chart review of these 57 positive samples showed that the LA result was false-positive in 31 (54%), true-positive in 22 (38%), and indeterminate in 4 (7%) samples. Therapy was not altered on the basis of any of the true-positive LA results. The 31 false-positive results led to additional cost, prolonged hospitalization, and some clinical complications. Total patient charges were $175,000 ($7,954 per true-positive), with no detectable clinical benefit. Our retrospective study does not support the current use of LA for rapid antigen detection. What, if any, specific indications exist for this test remain to be elucidated.