Olga Zając-Spychała

Serratia species are Gram-negative pathogens responsible for a wide range of nosocomial infections. This multicenter nationwide retrospective study aimed to describe the epidemiology, clinical characteristics, antimicrobial susceptibility, and outcomes of Serratia infections in pediatric oncology patients and hematopoietic stem cell transplantation (HSCT) recipients in Poland between 2012 and 2023. A total of 36 Serratia infection episodes were identified in patients under 20 years of age, including 30 cases (83.3%) in the oncological (OHD) group and six (16.7%) among HSCT recipients. The median age was 4.30 years. The most common underlying diseases were acute lymphoblastic leukemia (36.1%) and central nervous system tumors (16.7%). Bloodstream infections predominated in OHD patients (33.3%), whereas urinary tract infections were most frequent in HSCT recipients (83.3%). S. marcescens was the most commonly isolated species. More than half of isolates (53.3%) showed antimicrobial resistance, with extended-spectrum β-lactamase (ESBL)-producing strains in 26.7% and AmpC β-lactamase-producing strains in 13.3%. Multidrug resistance occurred in 30%. Treatment most often included amikacin, piperacillin/tazobactam, and carbapenems. Five deaths occurred in the OHD group and one in the HSCT group, none directly related to Serratia infection. Although uncommon, Serratia infections remain clinically relevant due to their high antimicrobial resistance, underscoring the need for antimicrobial stewardship.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) introduced an important public health threat in the world beginning in 2019. The aim of the study was to describe the clinical characteristics, treatment methods and outcomes of pediatric cancer patients and HSCT recipients who developed SARS-CoV-2 infection between 2020 and 2023 in Poland. During the study period among all pediatric oncological patients, 496 children (12.2%), i.e. 204 girls and 292 boys were at least one detected positive during anticancer therapy. Among HSCT recipients at least one episode of SARS-CoV-2 infection was diagnosed in 41 (6.0%; p < 0.001 oncology vs. transplant) patients, i.e. 10 girls, 31 boys including 39 (7.6%) after allo-HSCT and 2 (1.2%) after auto-HSCT (p = 0.001 allo vs. auto). SARS-CoV-2 infection has mild-moderate course in majority of pediatric cancer patients and transplant recipients, however, the presence of severe or critical illness is higher than in the general pediatric population. Interestingly, we observed less severe clinical courses of SARS-CoV-2 infection in the recent year than at the beginning of pandemic.

Introduction: Invasive fungal disease (IFD) remains a major concern in patients with hemato-oncologic conditions. Timely diagnosis and appropriate therapy, as well as confirmed positive clinical outcome, are crucial for early control of the disease. The improvement in the radiologic manifestations of IFD allows the resumption of anticancer treatment. Material and methods: The aim of the study was the analysis of clinical, laboratory and radiologic characteristics of probable and proven IFD and the moment of diagnosis and reassessment. Results: In the analyzed period, 54 episodes of pulmonary IFD (proven or probable) were identified in 44 patients. To assess response to treatment, chest computed tomography (CT) scans were performed at a median of 22 days postdiagnosis. Conclusions: There was a correlation between laboratory parameters, especially C-reactive protein (CRP), and radiologic improvement regarding the number of nodules assessed 21–30 days postdiagnosis. If laboratory progression is observed, it seems to be beneficial to perform radiologic control. Keywords: invasive fungal disease reassessment computed tomography inflammatory markers

Background: Staphylococcus spp. represent the most prevalent Gram-positive organisms in children with malignancies or undergoing haematopoietic cell transplantation (HCT), contributing to significant morbidity and mortality. This study aimed to assess the epidemiology, risk factors, treatment strategies, and outcomes of staphylococcal infections (SIs) in paediatric haemato-oncology (PHO) and HCT patients in Poland over a 12-year period. Methods: A retrospective, multicentre study was conducted across 17 paediatric oncology centres in Poland. The clinical and microbiological data of patients under the age of 18, diagnosed with malignancies or post-HCT, were analysed for confirmed SI between 2012 and 2023. The variables assessed included demographics, underlying conditions, infection type and source, antimicrobial susceptibility, treatment, and 30-day infection-free survival. Results: Among 1725 patients with SI, 1433 were PHO and 292 were HCT patients. The cumulative incidence of SI was 12.7% in PHO and 14.3% in HCT patients (p = 0.008). The 30-day survival rate was significantly higher in PHO compared to HCT patients (98.4% vs. 93.2%, p < 0.001). Most deaths were caused by S. epidermidis, S. haemolyticus, and S. hominis, predominantly involving methicillin-resistant coagulase-negative Staphylococci (MRCNS). Multivariate Cox regression identified undergoing HCT (HR = 3.0, 95% CI: 1.6–5.6, p < 0.001) and treatment of infection > 10 days (HR = 2.0, 95% CI: 1.1–3.6, p = 0.019) as independent risk factors for mortality. Conclusions: Staphylococcal infections pose a significant challenge in paediatric oncology and transplant populations. Optimising prevention, diagnostics, and antimicrobial therapy is crucial for improving outcomes in these high-risk groups.

Background: Acinetobacter, specifically A. baumannii, are becoming a great threat to hospitalized patients due to increasing antibiotic resistance. The aim of this study was to describe the epidemiology, clinical characteristics, antimicrobial susceptibility pattern and outcome of Acinetobacter infections in pediatric cancer patients and hematopoietic stem cell transplant (HSCT) recipients in Poland. Methods: A total of 125 episodes of Acinetobacter species infections were reported in patients n = 106; 84.8%) and HSCT group (n = 19; 15.2%). Each episode represented a separate infection event; therefore, a patient who was infected more than once during the course of treatment was counted for each infection episode. Results: A. baumannii is the most common Acinetobacter species in all groups. The most common diagnoses in OHD group were acute lymphoblastic leukemia (ALL) (n = 32; 30.2%) and acute myeloid leukemia (AML) (n = 13; 12.3%). The most common underlying diseases that were indication for HSCT were hemophagocytic lymphohistiocytosis (n = 3; 15.8%) and neuroblastoma (n = 3; 15.8%). Mortality was significantly higher in the HSCT group compared to the OHD group. In the OHD group, deaths did not correlate with the type of antibiotic, with an exception for gentamicin, which correlated with higher mortality. In the HSCT group, deaths did not correlate with the type of antibiotic, except for levofloxacin that was correlated with a higher mortality rate. Conclusions: Acinetobacter infections are a great danger to immunocompromised patients. More research is needed in order to prevent and treat antibiotic-resistant bacteria.

Background: Pseudomonas aeruginosa (PSA) infections are associated with a high recurrence rate and high mortality in immuno-compromised patients. There are limited studies regarding pediatric hematopoietic cell transplantation recipients. Aim: The nationwide multicenter study was conducted to analyze the epidemiology of PSA infections in children treated with chemotherapy (PHO, pediatric hematology and oncology) or undergoing hematopoietic allogeneic or autologous cell transplantation (HCT) in the period 2014–2023. Methods: We retrospectively analyzed the clinical and microbiological data of children who underwent anticancer therapy or hematopoietic cell transplantation in 17 Polish PHO centers and six pediatric HCT centers. The data were collected in two-year intervals. Results: During the 10-year study period, a total of 1629 HCTs (both autologous and allogeneic) and 9614 children newly diagnosed with neoplasms were analyzed. The cumulative incidence of PSA infection was similar in both groups (6.71% in PHO vs. 6.32% in HCT, p = 0.624). The total number of PSA bloodstream infections was comparable in the PHO and HCT groups (31.9% vs. 26.2%; p = 0.223). In both analyzed groups, the antipseudomonal drugs of choice were as follows: meropenem, ceftazidime, and tazobactam/piperaciline in combination with other antibiotics. In the HCT group, high rates of meropenem (20.4%) and tazobactam/piperaciline (18.4%) non-susceptibility were observed. This led to colistin therapy in 5.3% of patients. There was no difference in the median antibiotic therapy time in both groups; however, the survival rates from PSA infection were significantly lower in the HCT group (89.3% vs. 96.0%, p = 0.004). Conclusions: Although the risk of infection and the occurrence of resistant bacterial strains in HCT patients were comparable with those in PHO patients, the outcome of PSA infections was better in the PHO setting.

Background: Acinetobacter, significantly A.baumannii, are becoming a great threat to hospitalized patients due to increasing antibiotic resistance. The aim of this study was to describe the epidemiology, clinical characteristic, antimicrobial susceptibility pattern and outcome of Acinetobacter infections in pediatric cancer patients and HSCT recipients in Poland. Methods: a total of 125 episodes of Acinetobacter species infections were reported in pa-tients < 18 years treated in Polish pediatric hematology and oncology centers over a pe-riod from 2012 to 2023. Infections were subdivided into oncohematological diseases (OHD) group (n=106; 84,8%) and hematopoietic stem cell transplant (HSCT) group (n=19; 15,2%). Results: A.baumannii is the most common Acinetobacter species in all groups. The most common diagnoses of infected patients in OHD group were: ALL (n=32; 30.2%) and AML (n=13; 12.3%). The most common underlying disease that was indication for HSCT among infected patients were hemophagocytic lymphohistiocytosis (n=3; 15.8%) and neuroblastoma (n=3; 15.8%). In OHD group, deaths did not correlate with the type of antibiotic, with an exception for gentamicin, which correlates with higher mortality. In HSCT group, deaths did not correlate with the type of antibiotic, except for levofloxa-cin that was correlated with higher mortality rate. Mortality was significantly higher in the HSCT group compared to the OHD group. Conclusions: Acinetobacter infections are a great danger to immunocompromised pa-tients. More research is needed in order to prevent and treat antibiotic resistant bacteria.

Neutropenia associated with onco-hematological treatment may contribute to high-mortality infections, especially caused by multidrug-resistant pathogens. In a 4-year-old girl treated due to early isolated central nervous system (CNS) relapse of B-cell acute lymphoblastic leukemia, skin lesions with traits of Fournier’s gangrene caused by Klebsiella pneumoniae carbapenemase (KPC)-producing Pseudomonas aeruginosa (PsA). The patient was treated with broad-spectrum antibiotic therapy and the wound was debrided and treated with VAC (vacuum-assisted closure) successfully. Despite further intensive anticancer treatment complicated by reactivation of PsA infection, there was no other episode of invasive infection anymore and, nowadays, the patient has been in complete remission for 13 months. The aim of this report is to mention that Fournier’s gangrene is a rapid and potentially fatal infectious complication of chemotherapy in onco-hematological pediatric patients, especially if caused by MDR (multidrug-resistant) pathogens. Successful treatment of this necrotizing fasciitis saves a patient’s life and allows to continue an effective anticancer therapy.

Background: Soft tissue undifferentiated sarcomas (STUS) are an ultra-rare and heterogenous group of mesenchymal neoplasms often lacking known genetic abnormalities with a marked vulnerability towards intensive therapy such as invasive surgery and high dose chemotherapy. Despite aggressive treatment, they are usually associated with dismal outcomes. Case presentation: Here we describe two cases of STUS in 3-week-old and 3-month-old infants localized on the neck and the trunk area. Discussion: In both cases, the malignancy had a fatal outcome due to the toxicity of intensive therapy in one case and the progression of the disease in the other. The purpose of this report is to discuss the clinical challenges of managing infancy-related STUS such as limited treatment options and poor prognosis.

Background: Klebsiella pneumoniae is a nosocomial pathogen that causes severe infections in immunocompromised patients. The aim of the study was to conduct a microbiological and clinical analysis of K. pneumoniae infections in children with malignancies or undergoing hematopoietic cell transplantation in Poland. Methods: We conducted a retrospective, multicenter study including children and adolescents under 19 years old treated between 2012 and 2021. We analyzed patients’ characteristics, microbiological data, and the outcomes of antibiotic therapy. Results: A total of 9121 newly diagnosed children were treated for malignancy and 1697 pediatric patients underwent hematopoietic cell transplantation. K. pneumoniae infections were diagnosed in 527 patients. Their overall incidence was 4.86% in pediatric hematology and oncology patients and 4.95% in patients who underwent hematopoietic cell transplantation. The incidence of infection was higher in patients with acute leukemia than with solid tumors (7.8% vs. 4.1%; OR = 2.0; 95% CI = 1.6–2.4; p < 0.0001). The most frequent source of infection was in the urinary tract at 55.2%. More than 57% of K. pneumoniae strains were extended-spectrum β-lactamase-positive and almost 34% were multidrug-resistant. Infections with K. pneumoniae contributed to death in 3.22% of patients. Conclusions: K. pneumoniae is one of the most critical pathogens in children suffering from malignancies or undergoing hematopoietic cell transplantation. The incidence of multidrug-resistant K. pneumoniae strains is increasing and contributing to poor clinical outcome.