<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><strong><span style="font-family: 'Times New Roman',serif;">Timeliness. </span></strong><span style="font-family: 'Times New Roman',serif;">Despite the successful use of diagnostic biomarkers in various fields of medicine (for example, D-Dimer in pulmonary embolism, natriuretic peptide in acute heart failure, Troponin I in myocardial infarction), accurate and timely diagnosis of bacterial infections remains a problem. Reliable clinical or microbiological parameters that can be used to diagnose bacterial infections and exclude infections have until recently been absent. The main drawbacks of many modern microbiological diagnostic methods are delay in time (for example, culturing methods), not optimal sensitivity (for example, blood cultures) and low specificity due to contamination (for example, sputum culture), while others do not lend themselves to routine diagnosis, because of their invasive nature (e.g., lung biopsy).</span></p>
<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><span style="font-family: 'Times New Roman',serif;">Previous studies have examined the use of tumor necrosis factor-alpha (TNF-</span><span style="font-family: 'Times New Roman',serif;">&alpha;</span><span style="font-family: 'Times New Roman',serif;">), interleukin-6 (IL-6) and C-reactive protein for infection diagnosis, bacteremia prognosis, disease severity and mortality. A common obstacle to the widespread clinical application of these biochemical markers is their non-specificity and the lack of correlation between the severity of the disease and the concentration of the marker in the body.</span></p>
<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><span style="font-family: 'Times New Roman',serif;">It was quite by chance discovered that bacterial infection increases the concentration of PCT in the blood. In the late 1980s, it was found that with cancer of the thyroid and some forms of lung cancer, along with an increase in Calcitonin (CT), the level of Procalcitonin (PCT) also increases. In 1992, the continued presence of CT and PCT in the blood in patients with burns was demonstrated. Moreover, in some patients with septicemia high levels of PCT were found, while CT values remained normal.</span></p>
<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><strong><span style="font-family: 'Times New Roman',serif;">Characteristic.</span></strong><span style="font-family: 'Times New Roman',serif;"> Procalcitonin is a polypeptide, the precursor of the hormone Calcitonin, which does not show hormonal activity and is produced during inflammation. PCT does not affect the metabolism of calcium. Normally, all PCT is converted into Calcitonin in C-cells of the thyroid gland in response to hormonal stimulants and practically does not enter the bloodstream. It has been experimentally proved that an increase in the level of PCT in blood plasma occurs only under the action of bacterial endotoxins and strongly correlates with the severity of bacterial infection. Due to a rapid immune response, the PCT levels increase within 6-12 hours after infection and in the case when the infection is controlled by the immune system or by antibiotic therapy, the amount of circulating in blood PCT daily decreases by half.</span></p>
<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><span style="font-family: 'Times New Roman',serif;">In general, the concentration of PCT circulating in the blood is extremely low. In healthy donors, it is determined at the level of 0.01 ng/ml. In viral infections and during inflammation, the level of PCT rises slightly, rarely reaching 1 ng/ml. However, in severe bacterial infections, it can grow from 20 to 200 ng/ml.</span></p>
<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><strong><span style="font-family: 'Times New Roman',serif;">Study. </span></strong><span style="font-family: 'Times New Roman',serif;">Based on these data, PCT was proposed as a candidate marker for the diagnosis of bacterial infections and as a criterion for evaluating the effectiveness of antibiotic action. Studies conducted to compare the values ​​of CRP and PCT and their correlation in bacteremia, the syndrome of systemic inflammatory reaction (SIRS), sepsis and septic shock, conducted in emergency departments [1], showed the following results:</span></p>
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<img width="100%" src="/media/news/uploads/news/pct_eng.jpg">
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<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><span style="font-family: 'Times New Roman',serif;">&nbsp;</span></p>
<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><span style="font-family: 'Times New Roman',serif;">The level of CRP has increased with bacteremia, but did not allow differentiation of the type of infection (the level of CRP is increasing with any inflammation, regardless of etiology), while the level of PCT remained low with non-bacterial infection, and in bacteremia and septic shock its values ​​were highly informative and were more than 2.5 ng/ml.</span></p>
<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><span style="font-family: 'Times New Roman',serif;">Prior to 2011, observations and studies were conducted in Switzerland, Germany, France, Denmark and China through selective control tests. The obtained data showed that the determination of PCT level significantly helps in the diagnosis and expediency of prescribing antibiotic therapy for bacterial infection, primary blood infection and bronchitis, exacerbation of chronic obstructive pulmonary disease, pneumonia (including fan-associated pneumonia), postoperative infections, severe sepsis/shock and infections of the upper respiratory tract [2].</span></p>
<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><strong><span style="font-family: 'Times New Roman',serif;">Gradation.</span></strong><span style="font-family: 'Times New Roman',serif;"> Based on the conducted studies, differentiation of PCT level with recommendations for the use of antibiotics was carried out. So, depending on the anamnesis, treatment with antibiotics should be started at a PCT concentration of 0.1-0.5 ng/ml; this may indicate local inflammation or local infection, also in such cases it is recommended to measure the PCT level again after 6-12 hours. Values ​​of PCT concentrations above 0.5 ng/ml are defined as pathological, with suspicion of septic syndrome. In the range of PCT from 0.5 to 2 ng/ml, the diagnosis of sepsis cannot be made with certainty, therefore it is recommended to repeat the PCT measurement after 6-24 hours to make an accurate diagnosis. If the level of PCT is unchanged or increased for more than 4 days, an evaluation of the ongoing therapy for sepsis should be made. The PCT level above 2 ng/ml is highly likely to indicate an infectious process with systemic inflammation, and a concentration of more than 10 ng/ml is observed exclusively in patients with severe sepsis or septic shock (daily monitoring of the PCT level remains important). It is important to note that, like any other diagnostic indicator, PCT should be used in a comprehensive manner in the context of other clinical parameters.</span></p>
<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><strong><span style="font-family: 'Times New Roman',serif;">Methods of diagnostics.</span></strong><span style="font-family: 'Times New Roman',serif;"> In daily laboratory diagnostics, the most commonly used is enzyme immunoassay. This is a quantitative method that satisfies threshold values ​​and is relatively easy to perform. The company "Diameb" can offer you ELISA kits for the determination of Procalcitonin both domestic and foreign manufacturers.</span></p>
<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><span style="font-family: 'Times New Roman',serif;">In the case of severe patients, if urgent results are to be obtained, the best solution is to use the immuno-chemiluminescent analysis (CLIA), which makes it possible to obtain the result after 17 minutes (on automatic CLIA analyzers of the Maglumi series). The incubation time in this method is only 15 minutes, and the reading takes only 3 seconds, at a sensitivity of 0.01 ng/ml PBC. For patients with suspicion, for example, for septic shock, this factor can reduce lethality and accelerate recovery.</span></p>
<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><span style="font-family: 'Times New Roman',serif;">And not the last in the diagnosis are rapid tests, the most relevant for medical institutions of primary and secondary levels. The threshold value of express tests offered by Diameb company is 1 ng/ml PCT, which, in combination with other diagnostic parameters, can be an indication for the prompt appointment of adequate antibiotic therapy.</span></p>
<p style="margin-bottom: 6.0pt; text-align: justify; line-height: normal; tab-stops: 372.0pt;"><strong><span style="font-family: 'Times New Roman',serif;">Conclusion.</span></strong><span style="font-family: 'Times New Roman',serif;"> So, given that improper diagnosis and administration of an inadequate antibiotic course causes resistance of microorganisms to their action, dysbacteriosis and side reactions, increases the cost of treatment, and that some infectious diseases are asymptomatic or with a slight deviation from the norm - the use of PCT as a criteria for deciding whether to initiate and/or discontinue antibiotic therapy has a tremendous impact on the success of treatment.</span></p>
<ol>
<li style="margin-bottom: 6.0pt; text-indent: -18.0pt; line-height: normal; tab-stops: 311.15pt;"><span style="font-family: 'Times New Roman',serif;">Y-L. Chan, C-P. Tseng, P-K. Tsay, S-S. Chang, T-F. Chiu, J-C. Chen: Procalcitonin as a marker of bacterial infection in the emergency department: an observational study. </span><span style="font-family: 'Times New Roman',serif;">BMC Medicine </span><span style="font-family: 'Times New Roman',serif;">2004, 8:R12 (</span><a href="https://ccforum.biomedcentral.com/articles/10.1186/cc2396"><span style="font-family: 'Times New Roman',serif;">https://ccforum.biomedcentral.com/articles/10.1186/cc2396</span></a><span style="font-family: 'Times New Roman',serif;">)</span></li>
<li style="margin-bottom: 6.0pt; text-indent: -18.0pt; line-height: normal; tab-stops: 311.15pt;"><span style="font-family: 'Times New Roman',serif;">Philipp&nbsp;Schuetz, Werner&nbsp;Albrich&nbsp;and&nbsp; Beat&nbsp;Mueller: Procalcitonin for diagnosis of infection and guide to antibiotic decisions: past, present and future. BMC Medicine 2011, 9:107 (</span><a href="https://bmcmedicine.biomedcentral.com/articles/10.1186/1741-7015-9-107"><span style="font-family: 'Times New Roman',serif;">https://bmcmedicine.biomedcentral.com/articles/10.1186/1741-7015-9-107</span></a><span style="font-family: 'Times New Roman',serif;">) </span></li>
</ol>