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IntroductionWhile intensive protocols in onco-haematology have improved survival rates for patients with haematological malignancies, they have also resulted in an increased incidence of infection associated with therapy-induced immunosuppression (including chemotherapy-induced febrile neutropenia; FN). The occurrence of FN, associated with high morbidity and mortality, necessitates broad-spectrum antibiotic therapy, occasioning delayed chemotherapy and resulting in a loss of opportunity for the patient. Considering that without an identified pathogen, a 10% mortality rate can ensue, documentation is essential to the optimisation of antibiotic therapy. However, blood culture (the reference test) is limited for several reasons: such as fastidious culture, antibiotic treatment prior to sampling or insufficient sample volume. Sequencing technologies have led to the development of diagnostic approaches based on the detection of circulating DNA in blood. This study will aim to assess the clinical utility of metagenomic next-generation sequencing (mNGS)-DISQVER technology in detecting pathogenic microorganisms from blood samples of patients undergoing high-risk FN treatment.Methods and analysisThis nationwide, prospective, multicentre, interventional, proof-of-concept clinical trial will enrol 200 patients. Will include patients≥18 years old, treated for malignancy, at high risk of FN (Multinational Association for Supportive Care in Cancer score≤21) with an expected duration of neutropenia≥7 days. Patients who received antibiotic treatment within 24 hours prior to enrolment, have previously participated and/or have enhanced protection will be excluded. The primary outcome will be determined by considering the microorganisms responsible for this FN, weighted by the assessment of an adjudication committee. Secondary outcomes will evaluate patient management depending on the arm. The second secondary outcome will be determined by the duration of conventional assessment, frequency of microorganisms detected during routine care and percentage distribution of theoretical adjustments made to anti-infective treatment based on microorganisms diagnosed using the mNGS-DISQVER tool as compared with conventional practices. Identifying the pathogens responsible for high-risk FN from a blood sample, using an unbiased technique, can provide microbiological documentation and may even reveal unexpected microorganisms in these profoundly immunocompromised patients.Ethics and disseminationThe protocol received approval from the Comité de Protection des Personnes Sud-Méditerranée II. All participants will provide informed consent before participation. The trial has been registered on ClinicalTrials.gov (identifier NCT06075888). The results of the main trial and each of the secondary endpoints will be submitted for publication in a peer-reviewed journal.Trial registration numberClinicalTrials.gov NCT06075888.

PurposeThere is a paucity of data regarding the utility of routine urine cultures in adults with febrile neutropenia (FN) without urinary symptoms receiving protocolised antibiotics. This is reflected by inconsistent recommendations in international and regional FN guidelines. We addressed this issue by retrospectively reviewing the impact of routine urine cultures on antibiotic management in haematology cancer inpatients at a tertiary hospital.MethodsAll haematology inpatients over a 5-year period (2011–2015) were retrospectively reviewed for episodes of FN (neutrophil count < 0.5 × 109/L and fever > 37.5 °C). For each episode, demographic data, urinary tract symptoms and signs (absence of which was termed ‘asymptomatic’), urinalysis and urine culture results, antibiotic therapy and duration, and patient outcomes were collected. A urine culture was considered positive if > 105 colony forming units (CFU)/L were detected. Empiric antibiotic therapy for FN consisted of intravenous piperacillin/tazobactam in stable patients, with the addition of vancomycin and a single dose of gentamicin if systemically compromised.ResultsFour hundred and thirty-three episodes of FN were identified in 317 patients. Urine cultures were performed in 362 (84%) episodes. Cultures were positive in 9 of 48 (19%) symptomatic episodes versus 8 of 314 (2.5%) asymptomatic episodes (RR = 7.4, p < 0.0001). A change in antibiotic management due a positive urine culture occurred in only 5 episodes (1.4%): 3 of 48 (6.3%) symptomatic and 2 of 314 (0.6%) asymptomatic episodes respectively (RR = 9.8, p = 0.01).ConclusionRoutine urine cultures in FN patients without urinary symptoms who are already receiving protocolised broad spectrum antibiotics rarely impact subsequent antibiotic management.

Gram-negative bacteria are responsible for an increasing number of deaths caused by antibiotic-resistant infections 1 , 2 . The bacterial natural product colistin is considered the last line of defence against a number of Gram-negative pathogens. The recent global spread of the plasmid-borne mobilized colistin-resistance gene mcr-1 (phosphoethanolamine transferase) threatens the usefulness of colistin 3 . Bacteria-derived antibiotics often appear in nature as collections of similar structures that are encoded by evolutionarily related biosynthetic gene clusters. This structural diversity is, at least in part, expected to be a response to the development of natural resistance, which often mechanistically mimics clinical resistance. Here we propose that a solution to mcr-1 -mediated resistance might have evolved among naturally occurring colistin congeners. Bioinformatic analysis of sequenced bacterial genomes identified a biosynthetic gene cluster that was predicted to encode a structurally divergent colistin congener. Chemical synthesis of this structure produced macolacin, which is active against Gram-negative pathogens expressing mcr-1 and intrinsically resistant pathogens with chromosomally encoded phosphoethanolamine transferase genes. These Gram-negative bacteria include extensively drug-resistant Acinetobacter baumannii and intrinsically colistin-resistant Neisseria gonorrhoeae , which, owing to a lack of effective treatment options, are considered among the highest level threat pathogens 4 . In a mouse neutropenic infection model, a biphenyl analogue of macolacin proved to be effective against extensively drug-resistant A. baumannii with colistin-resistance, thus providing a naturally inspired and easily produced therapeutic lead for overcoming colistin-resistant pathogens. The discovery and synthesis of a colistin congener provide a promising clinical lead against mcr-1 -encoding colistin-resistant pathogens, which are responsible for an increasing number of deaths from antibiotic-resistant infections.

Gram-negative bacteria produce outer membrane vesicles that play a role in the delivery of virulence factors to host cells. However, little is known about the membrane-derived vesicles (MVs) produced by gram-positive bacteria. The present study examined the production of MVs from Staphylococcus aureus and investigated the delivery of MVs to host cells and subsequent cytotoxicity. Four S. aureus strains tested, two type strains and two clinical isolates, produced spherical nanovesicles during in vitro culture. MVs were also produced during in vivo infection of a clinical S. aureus isolate in a mouse pneumonia model. Proteomic analysis showed that 143 different proteins were identified in the S. aureus-derived MVs. S. aureus MVs were interacted with the plasma membrane of host cells via a cholesterol-rich membrane microdomain and then delivered their component protein A to host cells within 30 min. Intact S. aureus MVs induced apoptosis of HEp-2 cells in a dose-dependent manner, whereas lysed MVs neither delivered their component into the cytosol of host cells nor induced cytotoxicity. In conclusion, this study is the first report that S. aureus MVs are an important vehicle for delivery of bacterial effector molecules to host cells.

Febrile neutropenia (FN) is the main reason for antibiotic prescription in hematology wards where, on the other hand, antibiotic stewardship (AS) is poorly explored. The objectives of the present study were to evaluate (1) the impact of an AS intervention on antibiotic consumption and (2) the applicability and acceptance rate of the intervention and its clinical impact. A persuasive AS intervention based on European Conference on Infection in Leukaemia (ECIL) guidelines for FN was implemented in a high-risk hematology ward in a tertiary referral public university hospital. This included the creation and diffusion of flow charts on de-escalation and discontinuation of antibiotics for FN, and the introduction in the team of a doctor dedicated to the implementation of flow charts and to antibiotic prescription revision. All consecutive patients receiving antibiotics during hospitalization were included. A segmented linear regression model was performed for the evaluation of antibiotic consumption, taking into account 1-year pre-intervention period and 6-month intervention period. Overall, 137 consecutive antibiotic prescriptions were re-evaluated, 100 prescriptions were for FN. A significant reduction of the level of carbapenem consumption was observed during the intervention period (level change (estimate coefficient ± standard error) = − 135.28 ± 59.49; p = 0.04). Applicability and acceptability of flow charts were high. No differences in terms of intensive care unit transfers, bacteremia incidence, and mortality were found. A persuasive AS intervention in hematology significantly reduced carbapenem consumption without affecting outcome and was well accepted. This should encourage further applications of ECIL guidelines for FN.

Candida auris is an emerging worldwide concern, but comparative data about the virulence of different C. auris lineages in mammalian hosts is lacking. Different isolates of the four prevalent C. auris clades (South Asian n = 5, East Asian n = 4, South African n = 5, and South American n = 5) were compared to assess their virulence in a neutropenic murine bloodstream infection model with C. albicans as reference. C. auris, regardless of clade, proved to be less virulent than C. albicans. Highest overall mortality at day 21 was observed for the South American clade (96%), followed by the South Asian (80%), South African (45%) and East Asian (44%) clades. Fungal burden results showed close correlation with lethality. Histopathological examination revealed large aggregates of blastoconidia and budding yeast cells in the hearts, kidneys and livers but not in the spleens. The myocardium of apparently healthy sacrificed mice as well as of mice found moribund showed contraction band necrosis in case of all lineages. Regardless of clade, the heart and kidneys were the most heavily affected organs. Isolates of the same clade showed differences in virulence in mice, but a markedly higher virulence of the South American clade was clearly demonstrated.

Background: The aim of this study was to validate the ‘Predicting Infectious ComplicatioNs in Children with Cancer’ (PICNICC) clinical decision rule (CDR) that predicts microbiologically documented infection (MDI) in children with cancer and fever and neutropenia (FN). We also investigated costs associated with current FN management strategies in Australia. Methods: Demographic, episode, outcome and cost data were retrospectively collected on 650 episodes of FN. We assessed the discrimination, calibration, sensitivity and specificity of the PICNICC CDR in our cohort compared with the derivation data set. Results: Using the original variable coefficients, the CDR performed poorly. After recalibration the PICNICC CDR had an area under the receiver operating characteristic (AUC-ROC) curve of 0.638 (95% CI 0.590–0.685) and calibration slope of 0.24. The sensitivity, specificity, positive predictive value and negative predictive value of the PICNICC CDR at presentation was 78.4%, 39.8%, 28.6% and 85.7%, respectively. For bacteraemia, the sensitivity improved to 85.2% and AUC-ROC to 0.71. Application at day 2, taking into consideration the proportion of MDI known (43%), further improved the sensitivity to 87.7%. Length of stay is the main contributor to cost of FN treatment, with an average cost per day of AUD 2183 in the low-risk group. Conclusions: For prediction of any MDI, the PICNICC rule did not perform as well at presentation in our cohort as compared with the derivation study. However, for bacteraemia, the predictive ability was similar to that of the derivation study, highlighting the importance of recalibration using local data. Performance also improved after an overnight period of observation. Implementation of a low-risk pathway, using the PICNICC CDR after a short period of inpatient observation, is likely to be safe and has the potential to reduce health-care expenditure.

Febrile neutropenia (FN) is a life-threatening complication in patients undergoing cancer chemotherapy. This multicentric retrospective study aimed to evaluate the microbiological profile and factors affecting 30-day mortality in FN patients with solid malignancies. FN defined as single episode of oral temperature of > 101 °F (≥ 38.3 °C), with an absolute neutrophil count (ANC) < 500cells/mm 3 or ANC which is expected to decrease to < 500cells/mm 3 over next 48 h. All episodes of FN data that occurred between May 2021 and April 2023 were collected from three tertiary-care cancer centres and analysed. Among 710 patients who received chemotherapy over two years, 70 (9.8%) experienced FN. Antibiotic therapy was administered according to published guidelines. Of the 106 different cultures analysed, microbiological isolates were obtained from 23 (21.6%) cultures. Gram-negative bacteria were predominant (60.8%), followed by Gram-positive bacteria (30.43%). On the last day of follow-up, 52 (74.28%) patients were alive and 18 (25.71%) were dead. The 30-day mortality was significantly higher in patients with ANC < 500 cells/mm3 at the time of presentation ( p  = 0.001), who had positive cultures ( p  = 0.001), who developed FN on first-line chemotherapy ( p  = 0.020) and patients who did not receive prophylactic G-CSF support ( p  = 0.001). FN is a serious complication in patients undergoing chemotherapy for solid malignancies. This study identifies microbiological patterns and factors associated with higher 30-day mortality in FN among solid malignancy patients, suggesting areas for improved early recognition and tailored management.

Objective The aim of this study was to determine the predominant bacterial species causing bacteremia among febrile cancer patients, and their antibacterial resistance profiles at the Uganda Cancer Institute. Results We enrolled in-patients with a documented fever (≥ 37.5 °C). Bacteria from positive blood cultures were identified using standard methods biochemically. Antibacterial susceptibility testing was performed with the Kirby–Bauer disc diffusion method. From a total of 170 febrile episodes, positive blood cultures were obtained from 24 (14.1%). A positive culture was more likely to be obtained from a patient with neutropenia (P = 0.017). Of 22 (66.7%) Gram-negative bacteria isolated, half were E. coli (n = 11). Gram-negative compared to Gram-positive bacteria were most likely to be isolated from patients with a hematologic malignancy (P = 0.02) or patients with neutropenia (P = 0.006). Of the isolated Enterobacteriaceae 85% (n = 20) were resistant to three or more classes of antibiotic and 41% (n = 7) had extended spectrum beta-lactamases. Of the 11 Gram-positive bacteria isolated, the S. aureus isolate was methicillin resistant but susceptible to vancomycin. Multidrug resistant Gram-negative bacteria are the main cause of bacteremia in febrile cancer patients at the Uganda Cancer Institute. There is need for ongoing microbial surveillance, infection prevention and control, and antibiotic stewardship programs.

Febrile neutropenia (FN) is an inflammatory response causing fever that may develop during cancer therapy-induced neutropenia. FN may herald life-threatening infectious complications and should therefore be considered a medical emergency. Patients presenting with FN are routinely subjected to careful history taking and physical examination including X-rays and microbiological evaluations. Nevertheless, an infection is documented clinically in only 20–30% of cases, whereas a causative microbial pathogen is not identified in over 70% of FN cases. The oral cavity is generally only visually inspected. Although it is recognized that ulcerative oral mucositis may be involved in the development of FN, the contribution of infections of the periodontium, the dentition, and salivary glands may be underestimated. These infections can be easily overlooked, as symptoms and signs of inflammation may be limited or absent during neutropenia. This narrative review is aimed to inform the clinician on the potential role of the oral cavity as a potential source in the development of FN. Areas for future research directed to advancing optimal management strategies are discussed.