Use of an algorithm based on routine blood laboratory tests to exclude COVID-19 in a screening-setting of healthcare workers.

BACKGROUND: COVID-19 is an ongoing pandemic leading to exhaustion of the hospital care system. Our health care system has to deal with a high level of sick leave of health care workers (HCWs) with COVID-19 related complaints, in whom an infection with SARS-CoV-2 has to be ruled out before they can return back to work. The aim of the present study is to investigate if the recently described CoLab-algorithm can be used to exclude COVID-19 in a screening setting of HCWs. METHODS: In the period from January 2021 till March 2021, HCWs with COVID-19-related complaints were prospectively collected and included in this study. Next to the routinely performed SARS-CoV-2 RT-PCR, using a set of naso- and oropharyngeal swab samples, two blood tubes (one EDTA- and one heparin-tube) were drawn for analysing the 10 laboratory parameters required for running the CoLab-algorithm. RESULTS: In total, 726 HCWs with a complete CoLab-laboratory panel were included in this study. In this group, 684 HCWs were tested SARS-CoV-2 RT-PCR negative and 42 cases RT-PCR positive. ROC curve analysis showed an area under the curve (AUC) of 0.853 (95% CI: 0.801-0.904). At a safe cut-off value for excluding COVID-19 of -6.525, the sensitivity was 100% with a specificity of 34% (95% CI: 21 to 49%). No SARS-CoV-2 RT-PCR cases were missed with this cut-off and COVID-19 could be safely ruled out in more than one third of HCWs. CONCLUSION: The CoLab-score is an easy and reliable algorithm that can be used for screening HCWs with COVID-19 related complaints. A major advantage of this approach is that the results of the score are available within 1 hour after collecting the samples. This results in a faster return to labour process of a large part of the COVID-19 negative HCWs (34%), next to a reduction in RT-PCR tests (reagents and labour costs) that can be saved.

Bacterial influence on storage and mobilisation of metals in iron-rich mine tailings from the Salobo mine, Brazil.

In this study we investigated the potential effects of promoting bacterial activity on tailings from the Salobo iron-oxide copper­gold (IOCG) mine, Brazil. In particular we focussed on (1) the potential for mobilising additional Cu and (2) the effects of long-term storage on other metals. Unlike typical sulphide-ore tailings, the pH of the Salobo tailings is circumneutral and these tailings are dominated by Fe-bearing silicates and magnetite, with minor micrometre-scale encapsulated Cu-bearing sulphides. While these tailings do not produce acid mine drainage, an endemic strain of Acidithiobacillus ferrooxidans was isolated from the mine site. These bacteria were used in laboratory column leaching experiments of tailings material, which ran for up to 395 days, without the addition of ferrous iron. Bacteria-tailings interactions were typically maintained at a pH > 5, due to silicate-mediated pH buffering. This was eventually overcome after ~200 days by regular addition of acidic (pH 2.2) nutrient solution, as well as growth and acid generation by bacteria. Copper dissolution was not significantly enhanced by bacterial activity compared to abiotic control experiments while pH was >5. However, as the experiments were progressively acidified, additional Cu was mobilised in the biotic systems. The mineral alteration reactions produced abundant ferrihydrite precipitates within the tailings, which was enhanced by bacterial activity as the pH decreased. Adsorption of metal cations to these precipitates ensured that effluent solutions had only low levels (<0.5 mg/l) of dissolved trace metals such as As, Co, Pb, Zn, Se, Ni and Cr. These adsorption processes will strongly inhibit metal leaching from the tailings during long-term storage, as long as the iron oxidising bacteria are producing the requisite excess of ferrihydrite and the pH is >5. This case study shows that bacterially-mediated silicate weathering, in Fe(II)-bearing silicate rich tailings with only minor sulphides and Acidithiobacillus ferrooxidans can enhance the environmental stability of the tailings.

[Laboratory input. General practitioners positive about reflective testing]. / Eigen inbreng van het laboratorium. Huisartsen positief over 'reflecterend testen'.

OBJECTIVE: To investigate the opinion of general practitioners on reflective testing, i.e. the practice of additional tests being performed and comments added to the results by laboratory staff when appropriate. DESIGN: Descriptive. METHOD: In the eastern South Limburg region 155 general practitioners received a list of 10 fictitious patient cases, each involving the possible addition of a specific test. The general practitioners could choose what they preferred the laboratory to do: add tests, phone the general practitioner, add a written comment or do nothing. In addition the general practitioners were asked to judge the effect of additional tests and comments on patient management with respect to diagnosis, treatment and referral, using 200 laboratory reports from their own patients. RESULTS: The response to the fictitious cases was 45%. Most general practitioners favoured the laboratory taking the initiative by adding on tests and commenting on the results in the given clinical scenarios. 78% of the questionnaires accompanying the lab reports were returned by 87% of the general practitioners. In nearly all cases (99%) the service was marked as useful. In more than half of the cases (53%) reflective testing affected the measures taken by the general practitioners. CONCLUSION: Reflective testing was in general welcomed by the general practitioners. In the majority of cases this led to an improvement in the diagnosis or adjustment of treatment.

Differentiating transudative from exudative pleural effusion: should we measure effusion cholesterol dehydrogenase?

INTRODUCTION: Pleural effusions are often classified into transudates and exudates based on Light's criteria. In this study, the diagnostic properties of Light's criteria were compared to those of several other analytes for the classification of pleural fluids into transudative and exudative. METHODS: A total of 471 patients with pleural effusions were evaluated. In pleural effusions and simultaneously drawn blood samples, lactate dehydrogenase (LDH), total protein, albumin, cholesterol, amylase, glucose, pH and the cell number were measured. Retrospectively, the clinical records were used to establish a clinical diagnosis. The diagnostic properties of the biochemical tests were calculated using the clinical diagnoses as gold standard. RESULTS: By clinical diagnosis, 108 patients had transudative and 300 patients had exudative pleural effusions. In addition to pleural LDH activity (accuracy 89%, sensitivity 86%, specificity 97%) and fluid to serum LDH ratio (accuracy 89%, sensitivity 91%, specificity 85%), pleural cholesterol concentration readily identified exudates (accuracy 82%, sensitivity 76%, specificity 98%). Combination of these three parameters achieved a higher overall accuracy (accuracy 95%, sensitivity 93%, specificity 100%) than the Light's criteria (accuracy 93%, sensitivity 100%, specificity 73%). Combination of effusion cholesterol concentration and effusion LDH activity had the highest discriminatory potential (accuracy 98%, sensitivity 98%, specificity 95%). CONCLUSIONS: Including effusion cholesterol, concentration in the routine biochemical work-up of pleural fluid allows for correct classification of more pleural effusions than achieved by use of Light's criteria. Combination of cholesterol and LDH had the highest discriminatory potential and the added advantage that no patient plasma is needed for correct classification.

Screening of environmental DNA libraries for the presence of genes conferring lipolytic activity on Escherichia coli.

Environmental DNA libraries prepared from three different soil samples were screened for genes conferring lipolytic activity on Escherichia coli clones. Screening on triolein agar revealed 1 positive clone out of 730,000 clones, and screening on tributyrin agar revealed 3 positive clones out of 286,000 E. coli clones. Substrate specificity analysis revealed that one recombinant strain harbored a lipase and the other three contained esterases. The genes responsible for the lipolytic activity were identified and characterized.

Construction of environmental DNA libraries in Escherichia coli and screening for the presence of genes conferring utilization of 4-hydroxybutyrate.

Environmental DNA libraries from three different soil samples were constructed. The average insert size was 5 to 8 kb and the percentage of plasmids with inserts was approximately 80%. The recombinant Escherichia coli strains (approximately 930,000) were screened for 4-hydroxybutyrate utilization. Thirty-six positive E. coli clones were obtained during the initial screen, and five of them contained a recombinant plasmid (pAH1 to pAH5) which conferred a stable 4-hydroxybutyrate-positive phenotype. These E. coli clones were studied further. All five were able to grow with 4-hydroxybutyrate as sole carbon and energy source and exhibited 4-hydroxybutyrate dehydrogenase activity in crude extracts. Sequencing of pAH5 revealed a gene homologous to the gbd gene of Ralstonia eutropha, which encodes a 4-hydroxybutyrate dehydrogenase. Two other genes (orf1 and orf6) conferring utilization of 4-hydroxybutyrate were identified during subcloning and sequencing of the inserts of pAH1 and pAH3. The deduced orf1 gene product showed similarities to members of the DedA family of proteins. The sequence of the deduced orf6 gene product harbors the fingerprint pattern of enoyl-coenzyme A hydratases/isomerases. The other sequenced inserts of the plasmids recovered from the positive clones revealed no significant similarity to any other gene or gene product whose sequence is available in the National Center for Biotechnology Information databases.

[Evaluation of the use of an environmental medicine consulting center]. / Auswertung der Inanspruchnahme einer umweltmedizinischen Beratungsstelle.

At the Environmental Medical Consulting Centre 1677 consultations were carried out in 1991. The centre is established at the Medical Institute of Environmental Hygiene in Düsseldorf. There were 1129 (68%) short questions and 309 (18%) detailed consultations by phone or by letter. The most of the questions were asked by the general population. Other questions came from people at health offices, from general practitioners and from hospitals. No detail information about some socio-demographic data of this group was taken. The overwhelming topics of the questions were toxicological problems of harmful substances in indoor air or about the use of some products containing harmful substances. 239 (14%) people of the whole group got an appointment for a detailed medical consultation. Only data from 158 patients--visiting the office during January and September 1991--were evaluated in detail. On average the patients examined were 40 years old and mostly with a higher school degree. The most of the people complained about permanent polysomatic symptoms. A defined exposure was diagnosed for 31 (20%) patients, which resulted from pollution at work, at home or from the environment. The term Sick-Building-Syndrome were used for further 16 (10%) patients. In conclusion, the results of the study reveal a need of consultation with a specific orientation in Environmental Medicine. But, because of lack of data from other consulting offices in order to compare the results, no quantification of the need could be estimated.