Aztreonam-avibactam synergy, a validation and comparison of diagnostic tools

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 MBL-positive 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.

Analysis of a Combined HBHA and ESAT-6-Interferon-γ-Release Assay for the Diagnosis of Tuberculous Lymphadenopathies

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.

Efficacy and safety of baricitinib in hospitalized adults with severe or critical COVID-19 (Bari-SolidAct): a randomised, double-blind, placebo-controlled phase 3 trial

BACKGROUND

Baricitinib has shown efficacy in hospitalized patients with COVID-19, but no placebo-controlled trials have focused specifically on severe/critical COVID, including vaccinated participants.

METHODS

Bari-SolidAct is a phase-3, multicentre, randomised, double-blind, placebo-controlled trial, enrolling participants from June 3, 2021 to March 7, 2022, stopped prematurely for external evidence. Patients with severe/critical COVID-19 were randomised to Baricitinib 4 mg once daily or placebo, added to standard of care. The primary endpoint was all-cause mortality within 60 days. Participants were remotely followed to day 90 for safety and patient related outcome measures.

RESULTS

Two hundred ninety-nine patients were screened, 284 randomised, and 275 received study drug or placebo and were included in the modified intent-to-treat analyses (139 receiving baricitinib and 136 placebo). Median age was 60 (IQR 49-69) years, 77% were male and 35% had received at least one dose of SARS-CoV2 vaccine. There were 21 deaths at day 60 in each group, 15.1% in the baricitinib group and 15.4% in the placebo group (adjusted absolute difference and 95% CI - 0.1% [- 8·3 to 8·0]). In sensitivity analysis censoring observations after drug discontinuation or rescue therapy (tocilizumab/increased steroid dose), proportions of death were 5.8% versus 8.8% (- 3.2% [- 9.0 to 2.7]), respectively. There were 148 serious adverse events in 46 participants (33.1%) receiving baricitinib and 155 in 51 participants (37.5%) receiving placebo. In subgroup analyses, there was a potential interaction between vaccination status and treatment allocation on 60-day mortality. In a subsequent post hoc analysis there was a significant interaction between vaccination status and treatment allocation on the occurrence of serious adverse events, with more respiratory complications and severe infections in vaccinated participants treated with baricitinib. Vaccinated participants were on average 11 years older, with more comorbidities.

CONCLUSION

This clinical trial was prematurely stopped for external evidence and therefore underpowered to conclude on a potential survival benefit of baricitinib in severe/critical COVID-19. We observed a possible safety signal in vaccinated participants, who were older with more comorbidities. Although based on a post-hoc analysis, these findings warrant further investigation in other trials and real-world studies. Trial registration Bari-SolidAct is registered at NCT04891133 (registered May 18, 2021) and EUClinicalTrials.eu ( 2022-500385-99-00 ).

Optimization of the Transwell® assay for the analysis of neutrophil chemotaxis using flow cytometry to refine the clinical investigation of immunodeficient patients

Chemotaxis is the directed movement of neutrophils towards an infected site. This physiological process can be reproduced using a modified Boyden chamber, such as the Transwell® support. Different techniques can be used to count neutrophils after migration to the lower chamber of the holder. The present study supports the use of an optimized Transwell® assay coupled with a flow cytometry-based method (Sysmex XN-9000) to detect chemotaxis abnormalities. A reference interval of neutrophil's chemotaxis was determined as part of this work. A first step involves the extraction of neutrophils from whole blood. The migration of neutrophils from the upper to the lower support chamber is subsequently directed by a chemoattractant gradient using N-formyl-l-Methionyl-l-Leucyl-l-Phenylalanine (fMLP). Neutrophils collected in the lower chamber are finally counted by flow cytometry. The original protocol was optimized through the comparison of different parameters. The use of Polymorphprep®, in the extraction of neutrophils, showed an improvement of the neutrophils yield of 1.65 times (57.5% of recovery) compared to the extraction using the Ficoll-Hypaque® gradient. A solution containing 5% of Bovin Serum Albumin (BSA) was used to suspend the extracted neutrophils, stabilize their viability and preserve their integrity. The mechanical agitation of the Transwell® permeable supports during migration did not show an increase in neutrophil yield. A migration time of 1 h 30 was identified as the best time for collecting the largest number of neutrophils after migration. Finally, we demonstrated that scraping the bottom of the well after migration improved neutrophil collection from the lower chamber by 1.9-fold compared to a non-scraping method. In conclusion, our results support the use of Polymorphprep® and a 5% BSA solution in the suspension, without agitation of the medium. An incubation time of 1 h 30 was identified as optimal for neutrophil migration through the chamber. Scraping the bottom after neutrophil migration improved neutrophil collection yield. Normal adult values were obtained with directed migration equal to 32.4% ±13.41% on 15 men and 18 women.

Effect of anti-interleukin drugs in patients with COVID-19 and signs of cytokine release syndrome (COV-AID): a factorial, randomised, controlled trial

Background

Infections with SARS-CoV-2 continue to cause significant morbidity and mortality. Interleukin (IL)-1 and IL-6 blockade have been proposed as therapeutic strategies in COVID-19, but study outcomes have been conflicting. We sought to study whether blockade of the IL-6 or IL-1 pathway shortened the time to clinical improvement in patients with COVID-19, hypoxic respiratory failure, and signs of systemic cytokine release syndrome.

Methods

We did a prospective, multicentre, open-label, randomised, controlled trial, in hospitalised patients with COVID-19, hypoxia, and signs of a cytokine release syndrome across 16 hospitals in Belgium. Eligible patients had a proven diagnosis of COVID-19 with symptoms between 6 and 16 days, a ratio of the partial pressure of oxygen to the fraction of inspired oxygen (PaO₂:FiO₂) of less than 350 mm Hg on room air or less than 280 mm Hg on supplemental oxygen, and signs of a cytokine release syndrome in their serum (either a single ferritin measurement of more than 2000 μg/L and immediately requiring high flow oxygen or mechanical ventilation, or a ferritin concentration of more than 1000 μg/L, which had been increasing over the previous 24 h, or lymphopenia below 800/mL with two of the following criteria: an increasing ferritin concentration of more than 700 μg/L, an increasing lactate dehydrogenase concentration of more than 300 international units per L, an increasing C-reactive protein concentration of more than 70 mg/L, or an increasing D-dimers concentration of more than 1000 ng/mL). The COV-AID trial has a 2 × 2 factorial design to evaluate IL-1 blockade versus no IL-1 blockade and IL-6 blockade versus no IL-6 blockade. Patients were randomly assigned by means of permuted block randomisation with varying block size and stratification by centre. In a first randomisation, patients were assigned to receive subcutaneous anakinra once daily (100 mg) for 28 days or until discharge, or to receive no IL-1 blockade (1:2). In a second randomisation step, patients were allocated to receive a single dose of siltuximab (11 mg/kg) intravenously, or a single dose of tocilizumab (8 mg/kg) intravenously, or to receive no IL-6 blockade (1:1:1). The primary outcome was the time to clinical improvement, defined as time from randomisation to an increase of at least two points on a 6-category ordinal scale or to discharge from hospital alive. The primary and supportive efficacy endpoints were assessed in the intention-to-treat population. Safety was assessed in the safety population. This study is registered online with ClinicalTrials.gov (NCT04330638) and EudraCT (2020-001500-41) and is complete.

Findings

Between April 4, and Dec 6, 2020, 342 patients were randomly assigned to IL-1 blockade (n=112) or no IL-1 blockade (n=230) and simultaneously randomly assigned to IL-6 blockade (n=227; 114 for tocilizumab and 113 for siltuximab) or no IL-6 blockade (n=115). Most patients were male (265 [77%] of 342), median age was 65 years (IQR 54–73), and median Systematic Organ Failure Assessment (SOFA) score at randomisation was 3 (2–4). All 342 patients were included in the primary intention-to-treat analysis. The estimated median time to clinical improvement was 12 days (95% CI 10–16) in the IL-1 blockade group versus 12 days (10–15) in the no IL-1 blockade group (hazard ratio [HR] 0·94 [95% CI 0·73–1·21]). For the IL-6 blockade group, the estimated median time to clinical improvement was 11 days (95% CI 10–16) versus 12 days (11–16) in the no IL-6 blockade group (HR 1·00 [0·78–1·29]). 55 patients died during the study, but no evidence for differences in mortality between treatment groups was found. The incidence of serious adverse events and serious infections was similar across study groups.

Interpretation

Drugs targeting IL-1 or IL-6 did not shorten the time to clinical improvement in this sample of patients with COVID-19, hypoxic respiratory failure, low SOFA score, and low baseline mortality risk.

Funding

Belgian Health Care Knowledge Center and VIB Grand Challenges program.

Plasma zinc status and hyperinflammatory syndrome in hospitalized COVID-19 patients: An observational study

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.

Non-V600 BRAF mutations recurrently found in lung cancer predict sensitivity to the combination of Trametinib and Dabrafenib

Approximately half of BRAF-mutated Non-small cell lung cancers (NSCLCs) harbor a non-V600 BRAF mutation, accounting for ∼40,000 annual deaths worldwide. Recent studies have revealed the benefits of combined targeted therapy with a RAF-inhibitor (Dabrafenib) and a MEK-inhibitor (Trametinib) in treating V600 BRAF mutant cancers, including NSCLC. In contrast, sensitivity of non-V600 BRAF mutations to these inhibitors is not documented. Non-V600 mutations can either increase or impair BRAF kinase activity. However, impaired BRAF kinases can still activate the ERK pathway in a CRAF-dependent manner. Herein, beyond describing a cohort of BRAF mutant NSCLC patients and functionally analyzing 13 tumor-derived BRAF mutations, we demonstrate that both types of non-V600 BRAF mutations can be sensitive to clinically relevant doses of Dabrafenib and Trametinib in HEK293T cells, in lung epithelial cellular model (BEAS-2B) and in human cancer cell lines harboring non-V600 BRAF mutations. ERK activity induced by both types of these mutations is further reduced by combinatorial drug treatment. Moreover, the combination leads to more prolonged ERK inhibition and has anti-proliferative and pro-apoptotic effects in cells harboring both types of non-V600 BRAF mutations. This study provides a basis for the clinical exploration of non-V600 BRAF mutant lung cancers upon treatment with Trametinib and Dabrafenib.

[Comparative efficacy of antibiotic prophylaxis using cefoxitin in one or in three doses in cesarean section]

To compare the effectiveness of three doses and of a single dose of cefoxitin, a second-generation cephalosporin, in preventing infection after nonelective cesarean section, we carried out a prospective study in 255 women who underwent the procedure between March 1983 and February 1985. The rate of postoperative infection was 7% in the group that received three doses and 8% in the one-dose group. The sensitivity and specificity of perioperative cultures were low. The rate of asymptomatic bacteriuria was high, at 20%, but few symptomatic urinary tract infections were found. Routine antibiotic prophylaxis with a single dose is suggested for all nonelective cesarean sections.

Comparative cervical microflora shifts after cefoxitin or cefazolin prophylaxis against infection following cesarean section

The aerobic and anaerobic cervical microflora was determined before operation and on day 4 after operation in groups of women undergoing a clinical trial of prophylaxis with three doses of cefoxitin, cefazolin, or placebo for infectious complications of nonelective cesarean section. Floral shifts occurred post partum, with return of Escherichia coli and Bacteroides fragilis and a decrease in Candida colonization. No significant differences in flora existed preoperatively among patients receiving cefoxitin, cefazolin, or placebo, but by day 4, both antibiotic groups had greater enterococcal colonization. This difference was more marked with cefoxitin than with cefazolin. No difference in E. coli or B. fragilis colonization was noted by day 4 in placebo and antibiotic groups. Resistance developing in isolates in the antibiotic groups was mainly a result of enterococcal colonization. Results of this study indicate that a three-dose cephalosporin prophylactic regimen resulted in a significant selection of resistant enterococcal colonization but there was no increase in nosocomial infection in the antibiotic groups compared to the placebo group. There did not appear to be significant differences in either species selection or antibiotic resistance of aerobic or anerobic microflora between the cefoxitin and cefazolin groups.

Single oral dose of ornidazole in women with vaginal trichomoniasis

Fifty-nine women with trichomonal vaginitis were randomly allocated to receive treatment with a single oral dose of either 0.5, 1.0, or 1.5 g of ornidazole. One week after treatment, a parasitologic cure was observed in 100% of patients treated with 1.5 g, in 95% of patients treated with 1.0 g, and in 65% of patients given 0.5 g. At the one-month follow-up visit, the cure rate remained at 100% for the 1.5-g dose group but dropped to 85 and 45% in the 1.0- and 0.5-g dose groups, respectively. The disappearance of symptomatic complaints was also dose related: the clinical cure was 100, 85, and 40% at the first follow-up visit and 89, 80, and 30% at the second follow-up visit. Adverse effects of mild or moderate severity were reported by 13 patients. These were encountered mostly in the 1.5- and the 1.0-g dose groups. The most frequent adverse effects were dizziness and gastrointestinal distress. Laboratory safety test did not reveal any significant toxicity. This study confirms that single-dose treatment of trichomoniasis with an oral dose of 1.5 or 1.0 g of ornidazole is effective and well tolerated.

[Use of cephalosporins as antibiotic prophylaxis in cesarean section]

Cefoxitin, a second-generation cephalosporin, was compared with cefazolin, a first-generation cephalosporin, and a placebo in a prospective, double-blind study of antibiotic prophylaxis in women undergoing nonelective cesarean section. In the groups that received cefazolin or the placebo there eas no statistically significant change in colonization of the cervix by aerobic bacteria by the fourth day after the operation, but there was a statistically significant increase in colonization by anaerobes. Cefoxitin had the opposite effect. Of the 14 postoperative infections in 11 patients, significantly more were in patients who had received the placebo; the numbers were too small to show a difference in effectiveness between the two antibiotics. Of the microorganisms implicated as the infectious agents, group B Streptococcus was the most frequent aerobe, and Peptostreptococcus and Bacteroides bivius were the most frequent anaerobes. Among the 15 patients for whom at least one perioperative specimen yielded positive culture results, a postoperative infection developed in 5 of the 6 who received the placebo, 2 of the 4 who received cefazolin and 1 of the 5 who received cefoxitin.

Multicenter comparison of cefoxitin versus cefazolin for prevention of infectious morbidity after nonelective cesarean section

A randomized double-blind placebo-controlled comparison of prophylactic cefoxitin, an antibiotic with good activity against anaerobic bacteria, with cefazolin, an agent effective predominantly against aerobes, was undertaken in 354 women who underwent nonelective cesarean section (124 receiving cefoxitin, 119 cefazolin, and 111 placebo). Among the placebo group, 24.3% developed genital tract-related infection, in comparison to 5.6% of the cefoxitin patients and 6.7% of the cefazolin patients (P less than 0.001). Standard febrile morbidity, fever index, and duration of postoperative hospital stay were also significantly less in the antibiotic prophylactic groups. For patients with febrile morbidity, the mean fever index was less in the cefoxitin group (24.8 degree-hours) than that in the cefazolin group (42.7 degree-hours), and this difference approached statistical significance (P less than 0.1, greater than 0.05). Postoperative hospital stay longer than 1 week for infectious morbidity occurred in 26% of cefoxitin patients, a significantly lower incidence compared to the 66% rate for patients who received cefazolin, and the 57% incidence for patients in the placebo group (P less than 0.05).