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Introduction: Antimicrobial resistance is a growing problem that necessitates the development of new therapeutic options. Cefiderocol and aztreonam (AT) are often the last active β-lactams for treating metallo-β-lactamases (MBL)-producing Gram-negative bacilli. In these difficult-to-treat bacterial strains, AT resistance is frequently attributed to the co-occurrence of other resistance mechanisms. In the case of β-lactamases they can often be inhibited by avibactam. In the present study, we evaluated the use of the double-disc synergy test (DDST) as a screening tool for the detection of synergy between AT-avibactam (ATA). We validated both the Gradient Diffusion Strips (GDSs) superposition method and the commercially available Liofilchem’s ATA GDS. Materials and methods: We tested AT susceptibility in combination with ceftazidime-avibactam for 65 strains, including 18 Serine-β-Lactamase (SBL)- and 24 MBL-producing Enterobacterales, 12 MBL-producing P. aeruginosa, and 11 S. maltophilia isolates. Interpretation was done with EUCAST breakpoints (version 13.0), AT breakpoints being used for ATA. The accuracy and validity of the GDSs superposition method and ATA GDS were evaluated using an AT GDS applied on Mueller Hinton Agar plates supplemented with avibactam (MH-AV). A DDST was performed to screen for synergy between antibiotic combinations. Results: Using MH-AV, all SBL- and MBL-positive Enterobacterales were susceptible or susceptible at increased exposure to the combination AT-avibactam. In contrast, only 2 out of the 12 (17%) P. aeruginosa strains and 9/11 (82%) of the S. maltophilia strains were susceptible- or susceptible at increased exposure for the combination of AT-avibactam. The DDST detected all synergies, demonstrating a 100% sensitivity and 100% negative predictive value for all bacterial strains. Conclusion: The DDST is a sensitive tool for screening for antibiotic synergy. Unlike S. maltophilia and SBL- and MBL-positive Enterobacterales, most MBLpositive P. aeruginosa strains remain resistant to AT-avibactam. ATA GDS should be preferred for MIC determination of the AT-avibactam combination, while the GDSs superposition method can be used as an alternative to the commercial test. [ABSTRACT FROM AUTHOR]

Background and Objectives: The incidence of tuberculosis lymphadenopathy (TBLA) is increasing, and diagnostic procedures lack sensitivity and are often highly invasive. TBLA may be asymptomatic, and differential diagnosis with other adenopathies (ADPs) is difficult. We evaluated a blood-cell interferon-γ release assay (IGRA) with two different stage-specific mycobacterial antigens for the differential diagnosis of ADP suspected of mycobacterial origin. Methods: Twenty-one patients were included and divided into three groups: (1) cervical/axillar ADP (n = 8), (2) mediastinal ADP (n = 10), and (3) disseminated ADP (n = 3). The mycobacterial antigens used for the IGRA were the heparin-binding haemagglutinin (HBHA) and the early-secreted antigenic target-6 (ESAT-6), a latency-associated antigen and a bacterial replication-related antigen, respectively. Diagnosis of TBLA based on microbiological results and/or response to anti-TB treatment was obtained for 15 patients. Results: An IGRA profile highly suggestive of active TB (higher IFN-γ response to ESAT-6 compared to HBHA) was found for 3/6 TBLA patients from group 1, and for all the TBLA patients from groups 2 and 3, whereas this profile was not noticed in patients with a final alternative diagnosis. Conclusion: These results highlight the potential value of this combined HBHA/ESAT-6 IGRA as a triage test for the differential diagnosis of ADP. [ABSTRACT FROM AUTHOR]

Despite the low rates of bacterial co-/superinfections in COVID-19 patients, antimicrobial drug use has been liberal since the start of the COVID-19 pandemic. Due to the low specificity of markers of bacterial co-/superinfection in the COVID-19 setting, overdiagnosis and antimicrobial overprescription have become widespread. A quantitative and qualitative evaluation of urinary tract infection (UTI) diagnoses and antimicrobial drug prescriptions for UTI diagnoses was performed in patients admitted to the COVID-19 ward of a university hospital between 17 March and 2 November 2020. A team of infectious disease specialists performed an appropriateness evaluation for every diagnosis of UTI and every antimicrobial drug prescription covering a UTI. A driver analysis was performed to identify factors increasing the odds of UTI (over)diagnosis. A total of 622 patients were included. UTI was present in 13% of included admissions, and in 12%, antimicrobials were initiated for a UTI diagnosis (0.71 daily defined doses (DDDs)/admission; 22% were scored as 'appropriate'). An evaluation of UTI diagnoses by ID specialists revealed that of the 79 UTI diagnoses, 61% were classified as probable overdiagnosis related to the COVID-19 hospitalization. The following factors were associated with UTI overdiagnosis: physicians who are unfamiliar working in an internal medicine ward, urinary incontinence, mechanical ventilation and female sex. Antimicrobial stewardship teams should focus on diagnostic stewardship of UTIs, as UTI overdiagnosis seems to be highly prevalent in admitted COVID-19 patients. [ABSTRACT FROM AUTHOR]

• The majority of hospitalized COVID-19 patients are zinc deficient. • There is a weak correlation between plasma zinc and the length of hospital stay. • cHIS score, described by Webb et al., is externally validated in this study. • Current findings do not support plasma zinc as a robust prognostic factor. Zinc deficiency is associated with impaired antiviral response, cytokine releasing syndrome (CRS), and acute respiratory distress syndrome. Notably, similar complications are being observed during severe SARS-CoV-2 infection. We conducted a prospective, single-center, observational study in a tertiary university hospital (CUB-Hôpital Erasme, Brussels) to address the zinc status, the association between the plasma zinc concentration, development of CRS, and the clinical outcomes in PCR-confirmed and hospitalized COVID-19 patients. One hundred and thirty-nine eligible patients were included between May 2020 and November 2020 (median age of 65 years [IQR = 54, 77]). Our cohort's median plasma zinc concentration was 57 µg/dL (interquartile range [IQR] = 45, 67) compared to 74 µg/dL (IQR = 64, 84) in the retrospective non-COVID-19 control group (N = 1513; p < 0.001). Markedly, the absolute majority of COVID-19 patients (96%) were zinc deficient (<80 µg/dL). The median zinc concentration was lower in patients with CRS compared to those without CRS (-5 µg/dL; 95% CI = -10.5, 0.051; p = 0.048). Among the tested outcomes, zinc concentration is significantly correlated with only the length of hospital stay (rho = -0.19; p = 0.022), but not with mortality or morbidity. As such, our findings do not support the role of zinc as a robust prognostic marker among hospitalized COVID-19 patients who in our cohort presented a high prevalence of zinc deficiency. It might be more beneficial to explore the role of zinc as a biomarker for assessing the risk of developing a tissue-damaging CRS and predicting outcomes in patients diagnosed with COVID-19 at the early stage of the disease. [ABSTRACT FROM AUTHOR]