Evaluating the role of a fully automated SARS-CoV-2 antigen ECLIA immunoassay in the management of the SARS COV 2 pandemic on general population.

OBJECTIVES: Chemiluminescence immunoassay (CLIA) automated assays (fourth-generation antigen test) for SARS-CoV-2 detection are promising because of their analytical productivity, but have lower sensitivity and specificity than rt-PCR assays. The authors of this paper evaluated a recent immunoassay implemented on Siemens Atellica IM, investigating how much this could affect the actual feasibility of this diagnostic during the pandemic. METHODS: From the three-day routine 134 positive and 241 negative swab samples by rt-PCR test were evaluated, selected as 1/3 positive - 2/3 negative. RESULTS: Using rt-PCR as gold standard, the specificity of immunoassay was 96.7%, while sensitivity was 68.0%. Sensitivity is inversely proportional to the viral load: 100% for cycles threshold (CT) values from 14 to 29, 95% until 30 CT, then 85, 74, 72, 68%, for 31-35 CT respectively. CONCLUSIONS: Our study confirms the reliability of the fourth-generation antigen assay in recognizing negative samples. Conversely, sensitivity appears to be less reliable (68.0%) than reported in the literature. This could be due to a non-randomized study group: many swab samples were taken from patients with expected low viral load (hospitalized for COVID for more than 10-12 days or asymptomatic patients for epidemiological surveillance). The strong correlation of sensitivity and viral load could prove significant to track the infectiousness of infected people, as previous studies reported that a viral load of at least 10E6 copies of RNA/mL, corresponding to 25 CT, is the threshold of transmission of the disease.

Anti SARS-CoV-2 antibodies monitoring in a group of residents in a long term care facility during COVID-19 pandemic peak.

Objectives Clinical laboratories plays a key role in screening, diagnosis and containment of the Coronavirus 2019 infection epidemic. The etiological diagnosis presupposes the isolation of virus genetic material in the patient's biological sample but laboratory diagnostics also make use of searching possibility for immunoglobulin (Ig)G, IgM classes antibodies. The characteristics of the antibody response are not yet completely clear. Methods This study describes a serological monitoring of subjects, elderly nursing care residence guests, interested by a very large infection outbreak. After first nasopharyngeal swab, all the positive subjects (43) were monitored for the persistence of the virus infection through nasopharyngeal swab after 20 days (16-24), 32 days (28-36) and after 49 days (47-50). At the same time, during the second (day 32) and third (day 49) follow up, all the guests were investigated for IgM and IgG anti SARS-CoV-2 antibodies, by using a quantitative chemiluminescence method. Results Thirty two days after performing the first diagnostic swab, 39 of 43 patients (90%) had IgG higher than the cut off value. After 49 days the four patients with negative IgG were still negative. The comparison of the levels of IgG-Ab between the controls shows a significant decrease in concentrations (-10%). Conclusions Our study confirms that in most patients affected by COVID-19 there is a typical antibody response with IgG-Ab present in 90% of nursing care COVID-19 positive residence guests. For IgM-Ab only 23% of tested subjects were positive on the 32nd and 49th day of illness, always in parallel with the IgG-Ab positivity.

Prevalence of cervical colonization by Ureaplasma parvum, Ureaplasma urealyticum, Mycoplasma hominis and Mycoplasma genitalium in childbearing age women by a commercially available multiplex real-time PCR: An Italian observational multicentre study.

BACKGROUND: Mycoplasmas are frequently isolated from the genital tract. New molecular PCR-based methods for the detection of mycoplasmas can better define the real epidemiology of these microorganisms. The aim of this study was to evaluate the prevalence of mycoplasmas in a population of childbearing age women by means of PCR. METHODS: This 21-month multicentre observational study was conducted at four Italian clinical microbiology laboratories. Women reporting symptoms of vaginitis/cervicitis, or with history of infertility, pregnancy, miscarriage or preterm birth were included. Detection of Ureaplasma parvum, Ureaplasma urealyticum, Mycoplasma hominis, Mycoplasma genitalium was performed from cervical swabs by means of a commercially available multiplex real-time PCR. RESULTS: a total of 1761 women fulfilled the inclusion criteria and were included in the study. The overall prevalence was: U. parvum 38.3%, U. urealyticum 9%, M. hominis 8.6% and M. genitalium 0.6%. The proportion of foreign patients positive for U. parvum was significantly higher compared to Italian patients (37% vs 30.1%, p = 0.007) and also for overall mycoplasma colonization (53.4% vs 45.8%, p = 0.011). The number of symptomatic patients positive for M. hominis was significantly higher than that of negative controls (2.9% vs 1%, p = 0.036). A significant positive trend in mycoplasma colonization was found in relation to the pregnancy week for U. urealyticum (p = 0.015), M. hominis (p = 0.044) and for overall mycoplasma colonization (p = 0.002). CONCLUSION: multiplex RT-PCR can be a valuable tool to evaluate the real epidemiology of cervical mycoplasma colonization.

Epstein-Barr virus DNA load in chronic lymphocytic leukemia is an independent predictor of clinical course and survival.

The relation between Epstein-Barr virus (EBV) DNA load and clinical course of patients with chronic lymphocytic leukemia (CLL) is unknown. We assessed EBV DNA load by quantitative PCR at CLL presentation in mononuclear cells (MNC) of 220 prospective patients that were enrolled and followed-up in two major Institutions. In 20 patients EBV DNA load was also assessed on plasma samples. Forty-one age-matched healthy subjects were tested for EBV DNA load on MNC. Findings were validated in an independent retrospective cohort of 112 patients with CLL. EBV DNA load was detectable in 59%, and high (≥2000 copies/µg DNA) in 19% of patients, but it was negative in plasma samples. EBV DNA load was significantly higher in CLL patients than in healthy subjects (P < .0001). No relation was found between high EBV load and clinical stage or biological variables, except for 11q deletion (P = .004), CD38 expression (P = .003), and NOTCH1 mutations (P = .05). High EBV load led to a 3.14-fold increase in the hazard ratio of death and to a shorter overall survival (OS; P = .001). Poor OS was attributable, at least in part, to shorter time-to-first-treatment (P = .0008), with no higher risk of Richter's transformation or second cancer. Multivariate analysis selected high levels of EBV load as independent predictor of OS after controlling for confounding clinical and biological variables. EBV DNA load at presentation is an independent predictor of OS in patients with CLL.

Acute cytomegalovirus infection as a cause of venous thromboembolism.

Acute Human Cytomegalovirus (HCMV) infection is an unusual cause of venous thromboembolism, a potentially life-threatening condition. Thrombus formation can occur at the onset of the disease or later during the recovery and may also occur in the absence of acute HCMV hepatitis. It is likely due to both vascular endothelium damage caused by HCMV and impairment of the clotting balance caused by the virus itself. Here we report on two immunocompetent women with splanchnic thrombosis that occurred during the course of acute HCMV infection. Although the prevalence of venous thrombosis in patients with acute HCMV infection is unknown, physicians should be aware of its occurrence, particularly in immunocompetent patients presenting with fever and unexplained abdominal pain.

Four year longitudinal study of Mycobacterium tuberculosis complex isolates in a region of North-Eastern Italy.

Recent reports have suggested a change of Mycobacterium tuberculosis complex genetic diversity in Western Europe due to an increasing proportion of imported cases of tuberculosis (TB). This study analyzed a total of 705 M. tuberculosis strains isolated from 2006 to 2009 in Veneto, a North-Eastern Italian region, to see the impact of foreign-born cases vs. Italian patients on prevailing TB epidemiology. Strains were genotyped using spoligotyping followed by comparison with international genotyping database SITVIT2. Six spoligotyping clusters with suspected phylogeographical specificity for imported cases, were typed by 15-loci MIRUs for a finer characterization. Overall, 410 (58.16%) strains were isolated from foreign-born patients, while 295 (41.84%) were isolated from Italian patients. Older patients (>70 years, i.e., 46.4% of cases) predominated among Italians while younger age groups prevailed among foreign-born patients. Our results suggest that despite a high proportion of reactivation of latent TB infection in elderly Italian-born patients, active TB transmission between foreign-born and Italian patients may be ongoing, and argue in favor of an increased TB surveillance among immigrants to combat TB epidemic in Italy.

Clinical validation of Xpert MTB/RIF for the diagnosis of extrapulmonary tuberculosis.

Extrapulmonary tuberculosis (EPTB) accounts for more than 20% of tuberculosis (TB) cases. Xpert MTB/RIF (Xpert) (Cepheid, Sunnyvale, CA, USA) is a fully automated amplification system, for which excellent results in the diagnosis of pulmonary TB in highly endemic countries have been recently reported. We aimed to assess the performance of the Xpert system in diagnosing EPTB in a low incidence setting. We investigated with Xpert a large number of consecutive extrapulmonary clinical specimens (1,476, corresponding to 1,068 patients) including both paediatric (494) and adult samples. We found, in comparison with a reference standard consisting of combination of culture and clinical diagnosis of TB, an overall sensitivity and specificity of 81.3% and 99.8% for Xpert, while the sensitivity of microscopy was 48%. For biopsies, urines, pus and cerebrospinal fluids the sensitivity exceeded 85%, while it was slightly under 80% for gastric aspirates. It was, in contrast, lower than 50% for cavitary fluids. High sensitivity and specificity (86.9% and 99.7%, respectively) were also obtained for paediatric specimens. Although the role of culture remains central in the microbiological diagnosis of EPTB, the sensitivity of Xpert in rapidly diagnosing the disease makes it a much better choice compared to smear microscopy. The ability to rule out the disease still remains suboptimal.

Pulmonary disease due to Mycobacterium arosiense, an easily misidentified pathogenic novel mycobacterium.

Mycobacterium arosiense is a newly described species. After noticing it was misidentified as Mycobacterium intracellulare by the commercial identification system GenoType CM (Hein, Nehren, Germany), we detected 4 such strains among 33 that were previously misidentified as M. intracellulare. Three more strains were found among unidentified mycobacteria not tested previously with GenoType. The first case of pulmonary disease due to M. arosiense is reported here, and the novel species, of which so far only one strain had been investigated, is further characterized.