Microbiology laboratories where MALDI-TOF MS is available can benefit from its capacity to identify most clinically interesting non-tuberculous mycobacteria in a rapid, reliable, and inexpensive manner.

Objectives: High-quality diagnosis of bloodstream infections (BSI) is important for successful patient management. As knowledge on current practices of microbiological BSI diagnostics is limited, this project aimed to assess its current state in European microbiological laboratories. Methods: We performed an online questionnaire-based cross-sectional survey comprising 34 questions on practices of microbiological BSI diagnostics. The ESCMID Study Group for Bloodstream Infections, Endocarditis and Sepsis (ESGBIES) was the primary platform to engage national coordinators who recruited laboratories within their countries.

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Stricter criteria should be used for species of low clinical relevance, and less stringent criteria for species of high relevance in the local setting.3

Conflicting results have been reported regarding the association between early cytomegalovirus (CMV) reactivation and relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT). This prompted us to evaluate the impact of CMV reactivation on outcomes of 155 consecutive adult patients transplanted in our institution. In our study, CMV reactivation did not affect cumulative incidence (CI) of relapse in patients with lymphoproliferative disorders. However, the CI of relapse in patients with myeloproliferative disorders (AML and MPN) was 37% (95% CI, 21-53) in patients without CMV reactivation as opposed to 17% (95% CI, 9-28) in patients with CMV reactivation (p = 0.03). An important correlation between CMV reactivation and relapse was found in patients with MPN; the CI of relapse was 50% (95% CI, 12-80) in patients without CMV reactivation as opposed to only 7% (95% CI, 0-27) in patients with CMV reactivation (p = 0.02). A substantial reduction of relapse in myeloproliferative disorders associated with CMV reactivation was confirmed by multivariate analysis (HR 2.73; 95% CI, 1.09-6.82, p = 0.03) using time-dependent covariates for high-risk disease, older age, RIC conditioning, ATG, grade II-IV acute, and chronic GVHD. To our knowledge, we are the first to show an association of CMV reactivation with relapse reduction in MPN patients. This putative virus vs myeloproliferation effect warrants further research.

The ability of MALDI-TOF for the identification of nontuberculous mycobacteria (NTM) has improved recently thanks to updated databases and optimized protein extraction procedures. Few multicentre studies on the reproducibility of MALDI-TOF have been performed so far, none on mycobacteria. The aim of this study was to evaluate the reproducibility of MALDI-TOF for the identification of NTM in 15 laboratories in 9 European countries. A total of 98 NTM clinical isolates were grown on Löwenstein-Jensen. Biomass was collected in tubes with water and ethanol, anonymized and sent out to the 15 participating laboratories. Isolates were identified using MALDI Biotyper (Bruker Daltonics). Up to 1330 MALDI-TOF identifications were collected in the study. A score ≥ 1.6 was obtained for 100% of isolates in 5 laboratories (68.2–98.6% in the other). Species-level identification provided by MALDI-TOF was 100% correct in 8 centres and 100% correct to complex-level in 12 laboratories. In most cases, the misidentifications obtained were associated with closely related species. The variability observed for a few isolates could be due to variations in the protein extraction procedure or to MALDI-TOF system status in each centre. In conclusion, MALDI-TOF showed to be a highly reproducible method and suitable for its implementation for NTM identification.

Pneumocystis jirovecii pneumonia is a difficult invasive infection to diagnose. Apart from microscopy of respiratory specimens, two diagnostic tests are increasingly used including real-time quantitative PCR (qPCR) of respiratory specimens, mainly in bronchoalveolar lavage fluids (BAL), and serum β-1,3-d-glucan (BDG). It is still unclear how these two biomarkers can be used and interpreted in various patient populations. Here we analyzed retrospectively and multicentrically the correlation between BAL qPCR and serum BDG in various patient population, including mainly non-HIV patients. It appeared that a good correlation can be obtained in HIV patients and solid organ transplant recipients but no correlation can be observed in patients with hematologic malignancies, solid cancer, and systemic diseases. This observation reinforces recent data suggesting that BDG is not the best marker of PCP in non-HIV patients, with potential false positives due to other IFI or bacterial infections and false-negatives due to low fungal load and low BDG release.

Invasive candidosis is the most common invasive fungal infection in hospitalized patients and is associated with a high mortality rate. This is the first study from a Croatian tertiary care hospital describing epidemiology, risk factors and species distribution in patients with candidemia. A three-year retrospective observational study, from 2018 to 2020, was performed at the University Hospital Centre Zagreb, Zagreb, Croatia. A total of 160 patients with candidemia (n = 170 isolates) were enrolled. Candidemia incidence increased from 0.47 to 0.69 per 1000 admissions in 2018 and 2020, respectively. Ninety-five patients (58.38%) were in the intensive care unit. The main risk factors for candidemia were central venous catheter (CVC) (84.38%), previous surgical procedure (56.88%) and invasive mechanical ventilation (42.50%). Candida albicans was identified in 43.53% of isolates, followed by C. parapsilosis (31.76%) and C. glabrata (12.36%), C. krusei (5.29%), C. tropicalis (2.35%) and C. lusitaniae (2.35%). The study discovered a shift to non-albicansCandida species, particularly C. parapsilosis, and made it possible to determine the main tasks we should focus on to prevent candidemia in the hospital, these being mainly infection control measures directed towards prevention of catheter-related bloodstream infections, specifically comprising hand hygiene and CVC bundles of care. The potential benefit of fluconazole prophylaxis in certain populations of surgical patients could also be considered.