Submit Manuscript | http://medcraveonline.com Introduction Mycoses, or infections caused by microscopic fungi, have become a serious problem over the past two decades, affecting the morbidity and mortality of immunocompromised patients. Diffculties in the diagnosis of invasive fungal infections (IFI) lie in the fact that diagnosis requires a comprehensive assessment of the research results obtained, the clinical condition of the patient and the presence of risk factors. The clinical manifestations of fungal infections are nonspecifc and the fnal diagnosis depends on invasive procedures, which are not always feasible due to the severe condition of the patient and concomitant cytopenia. Early diagnosis of these life-threatening complications requires rapid, minimally invasive, highly sensitive and specifc tests, since late diagnosis and delay in therapy are potential risk factors for hospital mortality. 1 In most cases, the diagnosis of a fungal infection remains tentative. It can be confrmed by a combination of positive results of histological, microbiological, serological, molecular biological studies of primary sterile or potentially sterile material and the presence of clinical and instrumental symptoms of lesions of one or another organ. 2-4 Combinations of clinical, radiological data and serological determination of fungal antigens (mannan, galactomannan, (1,3)-β-D- glucan) are used. The concentration of these antigens depends on the degree of invasion of pathogens, 5,6 however, the sensitivity and specifcity may vary depending on the administration of other drugs (galactomannan test). 7,8 In addition, positive serological test results are possible in the absence of infection (with colonization). Therefore, the determination of fungal antigens is associated with the possibility of obtaining false positive and false negative results, which reduces the signifcance of these tests and does not completely guarantee a timely diagnosis. Determination of fungi by PCR is a promising method, but at the moment it is not recommended for widespread use in clinical practice. Due to the diffculties in diagnosis, international criteria for proving invasive fungal infections have been developed, which include possible, probable and proven IFIs. 9 a. Proven IFI: the patient has clinical signs of IFI and when examining biological material from a sterile locus, fungal structures are microscopically detected or fungal culture growth is obtained; b. Probable IFI: the immunocompromised patient has clinical signs of infection, as well as the presence of fungal elements on microscopy or inoculation of a culture of the fungus from a potentially sterile locus or positive serological tests (for example, a positive galactomannan test for aspergillosis); c. Possible IFI: the immunocompromised patient is at risk, has risk factors and clinical signs of infection, and all microbiological studies are negative or not carried out. J Microbiol Exp. 2021;9(4):132‒140. 132 ©2021 Kandaurava et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and build upon your work non-commercially. The use of biomarkers in the diagnostics of fungal infections in children with oncological and hematological diseases Volume 9 Issue 4 - 2021 Sviatlana Kandaurava, Michael Tchernovetski, Olga Aleinikova Belarusian Research Center for Pediatric Oncology, Hematology and Immunology, Republic of Belarus Correspondence: Sviatlana Kandaurava, Belarusian Research Center for Pediatric Oncology, Hematology and Immunology, Borovlyany, Minsk region, Republic of Belarus, Email Received: August 12, 2021 | Published: August 31, 2021 Abstract Background and purpose: Patients with hematological malignancies are at risk of fungal infections and require quick diagnostics infection complications. The following study aimed to evaluate the effectiveness and relevance of the use of biomarkers of procalcitonin (PCT), C-reactive protein (CRP), galactomannan (GM), and bis (methylthio) gliotoxin (BMGT) in the diagnosis of fungal infections in patients with oncological and hematological diseases. Materials and methods: The prospective study was conducted at the Belarusian Research Center for Pediatric Oncology, Hematology, and Immunology from April 2015 to January 2020. The study included 66 children with malignant hematological diseases aged 1 to 17 years. Clinical, microbiological, and statistical methods were used in the study. Results: In the case of fungemia in children with oncological and hematological diseases, the PCT level during the infectious episode was signifcantly lower than with bacterial infections of the bloodstream (p = 0.0063); and the СРR level in cases of fungal and bacterial infections did not differ signifcantly (p = 0.1719). Diagnostic study of GM in bronchoalveolar lavage had a high predictive value of a negative result (91.7%). The method’s sensitivity was higher than in the study of GM in serum (50% versus 0%). There was no correlation between serum BMGT levels as measured by HPLC and the presence of invasive aspergillosis in children. Conclusion: An increase in СRP levels with normal PCT levels in immunocompromised children with clinical signs of bloodstream infection is indicative of a fungal etiology of the disease. Determination of the optical density index of galactomannan in the bronchoalveolar fuid is a sensitive marker for diagnosing invasive pulmonary aspergillosis in children. We cannot recommend BMGT for the diagnostics of invasive aspergillosis in children. Keywords: biomarkers, infectious diseases, oncohematological diseases Journal of Microbiology & Experimentation Research Article Open Access