Introduction: BK polyomavirus is a double-stranded DNA virus from the Polyomaviridae family. According to DNA sequences, this virus can be classified into six genotypes. In hematological patients enrolled in allogeneic hematopoietic stem cell transplantation (HSCT) programs, it can lead to hemorrhagic cystitis. Aim: The aim of this study is calculating the prevalence of BK polyomavirus PCR (polymerase chain reaction) positivity in the blood and urine of patients involved in allogeneic HSCT, determining the predictive factors for clinical presentation of BK polyomavirus-associated hemorrhagic cystitis, as well as determining its effects on overall survival (OS) of the patients. Materials and methods: This retrospective cohort study enrolled 42 patients from the Clinic of Hematology of the University Clinical Center of Serbia. The presence of the virus in blood and urine was determined by the PCR method. The survival rate of the patients in relation to hemorrhagic cystitis was calculated with the Kaplan-Meier method and comparison was performed with the log-rank test. Results: A positive PCR result in the blood was found in 97.6% of the subjects, while urine tested positive in 100% of patients. The estimated survival time in patients without hemorrhagic cystitis was 44.357 months, while the group with the clinical presentation of hemorrhagic cystitis had an estimated survival time of 17.395 months. Based on the log-rank test, we found a significant difference in survival between those groups of patients (p = 0.049). With regards to leukocyte engraftment day, patients engrafted after D+14, had a higher frequency of hemorrhagic cystitis (p = 0.037). Conclusion: BK polyomavirus-associated hemorrhagic cystitis is a common complication of treatment in patients suffering from hematological malignancies who are enrolled in an alo-HSCT program, and has a significant impact on OS..

Introduction: Bacterial infections are common in patients enrolled in allogenic hematopoietic stem cell transplantation. Infections are the most common cause of illness and mortality in transplanted patients. The most common pathogens are Staphylococcus and Enterobacteriaceae, causing 25% of bacterial infections, each, followed by Enterococcus andP. aeruginosa. Aim: The aim of the paper is calculating the frequency of bacterial infections in patients enrolled in allogenic hematopoietic stem cell transplantation, at the Clinic for Hematology of the University Clinical Center of Serbia, as well as analyzing the epidemiological situation, the frequency of different clinical presentations of bacterial infections, and their effect on overall survival. Materials and methods: This retrospective cohort study enrolled 58 patients. The presence of bacteria was determined with standard microbial cultivation from samples. The diagnosis criteria for localized bacterial infection are a positive culture and characteristic clinical presentation. Sepsis is clinically diagnosed by a combination of a positive hemoculture and the existence of systemic inflammatory response. Management of bacterial infection starts empirically and is continued in keeping with antibiogram results. Patient survival was analyzed with the Kaplan-Meier method and compared with the log-rank test. Results: Bacterial infections were registered in 15 (25.9%) patients. The most common pathogens were Gram-negative bacteria (65.2%). The most common clinical presentation was sepsis (59.0%). Bacterial infection lethality was 60%. The Kaplan-Meier curve showed the median value for estimated patient survival in patients without bacterial infection to be 106.0 months (95% CI 85.2 - 163.3), while, for patients with bacterial infection, it was 14.0 (95% CI 8.9 - 19.1). The log-rank test showed a significant difference in the length of survival between these two groups (p < 0.001). Pseudomonas spp. was sensitive to colistin and/or meropenem. Klebsiella pneumoniae was sensitive to colistin. Conclusion: Bacterial infections are common at our clinic and are caused by endogenous opportunistic bacteria. Therefore, emphasis should be placed on the implementation of preventive measures aimed at preventing hospital-acquired infections.