Intérêts du dosage de procalcitonine en infectiologie

Interest of procalcitonin assay in case of infections diseases. In 70 % healthy adults (n = 258 age range 19–95 years), PCT serum concentrations were below the detection limit of the immunoluminometric assay (< 0.08 ng/mL). In 30 % healthy patients, PCT serum levels were low : 0.08–0.25 ng/mL. A prospective clinical study was performed to assess the accuracy of procalcitonin (PCT) in 162 patients with fever on admission to the hospital. 43 patients had PCT Values superior to 0.5 ng/mL. High PCT (> 5 ng/mL) was found in patients with severe acute bacterial infections. In 17 patients with viral meningitis PCT higher level was 0.33 ng/mL. Chronic non bacterial inflammation does not induce PCT, serum concentrations were < 5 ng/mL. PCT determination seem to be diagnostic tools of differentiations between bacterial infections with systemic reactions of the organism, (excluding patients with medullary thyroïd carcinoma) to viral infections, and non bacterial inflammation. PCT was a good marker to control the success of a therapeutic procedure.     

Le récepteur de la transferrine : intérêt dans l'exploration du statut martial

Transferrin receptor: contribution in assessment of iron status. Transferrin receptor is a transmembrane glycoprotein expressed by any cell type except erythrocytes. A soluble form of the transferrin receptor is detectable in human sera. Its concentration is proportional to tissue transferrin receptor cells. The primary function of transferrin receptor is to bind diferric transferrin and to internalize it by the process of receptor-mediated endocytosis. The first available tests were immunoenzymatic techniques; nowadays, nephelemetric or turbidimetric methods are developed and are automated on biochemistry or immunochemistry automates. However, due to lack of standardization, results obtained from different tests cannot be compared with respect to both reference and pathological ranges. Soluble transferrin receptor is a promising tool to detect coexisting iron deficiency in patients with anaemia of chronic diseases.     

Intérêt du signe du lacet devant un syndrome Dengue-like

A 26-year-old nurse presented with a three-day history of sudden onset of pyrexia of 39 °C, malaise, and a patchy maculopapular rash, after returning from a monthlong work in Senegal. A tourniquet was applied to help locate the vein for diagnostic blood sampling. After the procedure, a petechial rash erupted with a demarcation line below the level of the tourniquet. A diagnostic test for dengue fever was performed and confirmed by the polymerase chain reaction (PCR) to be positive for serotype DEN-1. The tourniquet test is performed by inflating a blood pressure cuff tied on the upper arm to a point midway between systolic and diastolic blood pressure for five minutes. The test is considered positive when there are 20 or more petechiae per square inch (6.25 cm²) on the forearm, and is one of several clinical parameters considered by the World Health Organization to be important in the diagnosis of dengue fever.     

Vingt-cinquième réunion du comité local de la Société de pathologie exotique, 24 novembre 2015

Bulletin de la Société de pathologie exotique -     

Intérêt du dosage des récepteurs solubles de la transferrine dans le dépistage de la carence martiale en fin de grossesse

Aim of the study is to compare serum transferrin receptor (sTfR) with ferritin in the diagnosis of iron deficiency at the end of pregnancy. Proteins were determinated by immunonephelometry in 60 patients on serum taken during labor. None of them presented serious inflammatory syndrome or malnutrition on the basis of PINI index. sTfR are >1.50 mg/l, the reference value for young women, by 72% of patients and ferritin < 20 μg/l among 50%. The two parameters are negatively correlated (r: 0.62). In patients with ferriprive anemia (hemoglobin < 10 g/dl), sTfR are highly enhanced (2.1–4.05). In non-anemic patients (hemoglobin > 12 g/dl) with ferritin level within reference value of non-menopaused women (7.17–52.6) sTfR are frequently >1.5 mg/l (0.7–3.09). Indeed, sTfR increase with physiological erythropoïesis activation observed at the end of pregnancy. It is essential to determine references values adapted at the end of pregnancy for an optimal interpretation of sTfR.     

Intérêt de la recherche de β2-transferrine dans des prélèvements susceptibles de contenir du LCR

When there is a clinical suspicion of CSF leakage, we can detect the presence of β2-transferrin in fluids from different origins. We used two techniques in the laboratory coupling electrophoresis with immuno-blotting. These two methods are realized on microsamples collected by syringe or on microcollagen sponges. The difference between the two methods concern the nature of the gel electrophoresis: agarose for the first one (zone electrophoresis) which allow separation of β1 and β2 transferrin by the electric charge, and agarose with ampholytes (isoelectrofocusing) allowing separation by isoelectric point of all transferrin isoforms. Whatever the method two controls are used: serum of the patient (negative control) and CSF (positive control).     

Les arbovirus ont aussi leur « rêve américain »

Some arboviruses that originated in the Old World have been introduced by humans into the American continent. The first of them was the yellow fever virus, coming from the West African coast with slaves in the 17th–19th centuries, followed by dengue viruses, which were always prevalent within the Americas. Next was theWest Nile virus, introduced in New York in 1999, that spread in only a few years over the whole continent. Then, Chikungunya virus arrived on Saint Martin Island in 2013 after its outbreak in Polynesia; it is now widespread in the Caribbean Islands and on the American continent from the United States to Brazil. Finally, Zika virus, already active in Asia and in the South Pacific region, was introduced in Brazil and spread between the southern part of United States and south Brazil. These unexpected emergences are the consequence of the generalization of transoceanic trading; so, it is humans who are truly responsible for such transportation of viruses from the African and Asian continents. The mechanisms of virus establishment in unusual ecosystems have to be analyzed in order to understand the conditions for the circulation of the viruses, which supposes an adaptation to new hosts and vectors that are sometimes local species (like Culex vectors of West Nile virus) but mainly previously introduced mosquitoes (like Aedes aegypti and/or Aedes albopictus). Over time, all these vectors developed a strong anthropophily and, most of them, a remarkable adaptation to urban environment; hence, these arboviruses can disseminate both in rural and urban context. This type of arboviral emergences will certainly continue in the following years and we must imperatively develop preventive strategies by detecting virus mutations with capacity for emergence, enhancing the sensibility and rapidity of epidemiological surveillance, and becoming ready to face such events that cause a truly international health crisis.