Anti-infectieux : supports moléculaires des résistances et innovations thérapeutiques

Antimicrobial resistance (AMR) is a major global public health concern, shared by a large number of human and animal health actors. Within the framework of a One Health approach, actions should be implemented in the environmental realm, as well as the human and animal realms. The Government of France commissioned a report to provide policy and decision makers with an evidential basis for recommending or taking future actions to mitigate AMR in the environment. We first examined the mechanisms that underlie the emergence and persistence of antimicrobial resistance in the environment. This report drew up an inventory of the contamination of aquatic and terrestrial environments by AMR and antibiotics, anticipating that the findings will be representative of some other high-income countries. Effluents of wastewater treatment plants were identified as the major source of contamination on French territory, with spreading of organic waste products as a more diffuse and incidental contamination of aquatic environments. A limitation of this review is the heterogeneity of available data in space and time, as well as the lack of data for certain sources. Comparing the French Measured Environmental Concentrations (MECs) with predicted no effect concentrations (PNECs), fluoroquinolones and trimethoprim were identified as representing high and medium risk of favoring the selection of resistant bacteria in treated wastewater and in the most contaminated rivers. All other antibiotic molecules analyzed (erythromycin, clarithromycin, azithromycin, tetracycline) were at low risk of resistance selection in those environments. However, the heterogeneity of the data available impairs their full exploitation. Consequently, we listed indicators to survey AMR and antibiotics in the environment and recommended the harmonization of sampling strategies and endpoints for analyses. Finally, the objectives and methods used for the present work could comprise a useful example for how national authorities of countries sharing common socio-geographic characteristics with France could seek to better understand and define the environmental dimension of AMR in their particular settings.

BACKGROUND: Kidney transplant recipients and patients receiving hemodialysis are immunocompromised populations that are prioritized for COVID-19 vaccination but were excluded from clinical trials of SARS-CoV-2 mRNA vaccines. Antibody titers and rates of seroconversion after vaccination are lower among patients with CKD and those taking immunosuppressants compared with controls. Data are lacking regarding their humoral response to vaccination to prevent COVID-19. METHODS: This investigation of early serological response after COVID-19 vaccination with the Pfizer/BioNTech (BNT162b2) mRNA vaccine included 78 patients undergoing hemodialysis, 74 kidney transplant recipients, and seven healthy controls. We recorded data from the medical file for various clinical parameters, including response to hepatitis B vaccination, and measured antibody titers against SARS-CoV-2 at 0, 14, 28, 36, and 58 days after the first injection. RESULTS: <0.0, respectively); nonresponders to HBV vaccine had the lowest anti-SARS-CoV-2 antibody titers. CONCLUSIONS: Our results suggest that the postvaccination humoral response is strongly inhibited by immunosuppressant therapy in kidney transplant recipients, and is reduced by the uremic condition in patients undergoing hemodialysis.

The ability of antimicrobial resistance (AR) to transfer between bacteria on mobile genetic elements (MGEs) can cause the rapid establishment of multidrug resistance (MDR) in bacteria from animals, leading to a foodborne risk to human health. To investigate MDR and its association with plasmids in Salmonella enterica, whole genome sequence (WGS) analysis was performed on 193 S. enterica isolated from U.S. food animals between 1998 and 2011, 119 of which were resistant to at least one antibiotic tested. Isolates represented 86 serovars and variants, as well as diverse phenotypic resistance profiles. A total of 923 AR genes and 212 plasmids were identified among the 193 strains. Every isolate contained at least one AR gene and at least one plasmid was detected in 157 isolates. Genes were identified for resistance to aminoglycosides (n=472), β-lactams (n=84), tetracyclines (n=171), sulfonamides (n=91), phenicols (n=42), trimethoprim (n=8), macrolides (n=5), fosfomycin (n=48), and rifampicin (n=2). The plasmid replicon types detected in the isolates were A/C (n=32), colE (n=76), F (n=43), HI1 (n=4), HI2 (n=20), I1 (n=62), N (n=4), Q (n=7), and X (n=35). Phenotypic resistance correlated with the AR genes identified in 95.4% of cases. Almost all AR genes were located on plasmids, with many of the plasmids encoding multiple AR genes. Thirteen AR genes representing five classes of antibiotics were arranged into six highly conserved cassette-like sequences and one pseudo-cassette (1: sul2, strAB, tetAR; 2: aac3-iid; 3: aph, sph; 4: cmy-2; 5: floR; 6: tetB; pseudo: aadA, aac3-VIa, sul1). These cassettes were present in multiple isolates and on plasmids of multiple replicon types. To determine the current distribution and frequency of these cassettes, the public NCBI database was analyzed, including WGS data on isolates collected by the USDA Food Safety and Inspection Service (FSIS) from 2014 to 2018. Cassette One, Cassette Four, and Cassette Five were significantly associated with cattle isolates while Cassette Six was significantly associated with chicken isolates. This study reveals that a diverse group of plasmids carrying AR genes are responsible for the phenotypic resistance seen in Salmonella isolated from U.S. food animals and many plasmids carry similar AR gene cassettes.

UNLABELLED: Class 1 integrons are genetic systems that enable bacteria to capture and express gene cassettes. These integrons, when isolated in clinical contexts, most often carry antibiotic resistance gene cassettes. They play a major role in the dissemination of antibiotic resistance among Gram-negative bacteria. The key element of integrons is the integrase, which allows gene cassettes to be acquired and shuffled. Planktonic culture experiments have shown that integrase expression is regulated by the bacterial SOS response. In natural settings, however, bacteria generally live in biofilms, which are characterized by strong antibiotic resilience and by increased expression of stress-related genes. Here, we report that under biofilm conditions, the stringent response, which is induced upon starvation, (i) increases basal integrase and SOS regulon gene expression via induction of the SOS response and (ii) exerts biofilm-specific regulation of the integrase via the Lon protease. This indicates that biofilm environments favor integron-mediated acquisition of antibiotic resistance and other adaptive functions encoded by gene cassettes. IMPORTANCE: Multidrug-resistant bacteria are becoming a worldwide health problem. Integrons are bacterial genetic platforms that allow the bacteria to capture and express gene cassettes. In clinical settings, integrons play a major role in the dissemination of antibiotic resistance gene cassettes among Gram-negative bacteria. Cassette capture is catalyzed by the integron integrase, whose expression is induced by DNA damage and controlled by the bacterial SOS response in laboratory planktonic cultures. In natural settings, bacteria usually grow in heterogeneous environments known as biofilms, which have very different conditions than planktonic cultures. Integrase regulation has not been investigated in biofilms. Our results showed that in addition to the SOS response, the stringent response (induced upon starvation) is specifically involved in the regulation of class 1 integron integrases in biofilms. This study shows that biofilms are favorable environments for integron-mediated acquisition/exchange of antibiotic resistance genes by bacteria and for the emergence of multidrug-resistant bacteria.

Wastewaters (WW) are important sources for the dissemination of antimicrobial resistance (AMR) into the environment. Hospital WW (HWW) contain higher loads of micro-pollutants and AMR markers than urban WW (UWW). Little is known about the long-term dynamics of H and U WW and the impact of their joined treatment on the general burden of AMR. Here, we characterized the resistome, microbiota and eco-exposome signature of 126 H and U WW samples treated separately for three years, and then mixed, over one year. Multi-variate analysis and machine learning revealed a robust signature for each WW with no significant variation over time before mixing, and once mixed, both WW closely resembled Urban signatures. We demonstrated a significant impact of pharmaceuticals and surfactants on the resistome and microbiota of H and U WW. Our results present considerable targets for AMR related risk assessment of WW.

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Profound lymphopenia is an independent predictor of adverse clinical outcomes in sepsis. Interleukin-7 (IL-7) is essential for lymphocyte proliferation and survival. A previous phase II study showed that CYT107, a glycosylated recombinant human IL-7, administered intramuscularly reversed sepsis-induced lymphopenia and improved lymphocyte function. Thepresent study evaluated intravenous administration of CYT107. This prospective, double-blinded, placebo-controlled trial was designed to enroll 40 sepsis patients, randomized 3:1 to CYT107 (10 µg/kg) or placebo, for up to 90 days. Twenty-one patients were enrolled (fifteen CYT107 group, six placebo group) at eight French and two US sites. The study was halted early because three of fifteen patients receiving intravenous CYT107 developed fever and respiratory distress approximately 5–8 h after drug administration. Intravenous administration of CYT107 resulted in a two–threefold increase in absolute lymphocyte counts (including in both CD4+ and CD8+ T cells (all p < 0.05)) compared to placebo. This increase was similar to that seen with intramuscular administration of CYT107, was maintained throughout follow-up, reversed severe lymphopenia and was associated with increase in organ support free days (OSFD). However, intravenous CYT107 produced an approximately 100-fold increase in CYT107 blood concentration compared with intramuscular CYT107. No cytokine storm and no formation of antibodies to CYT107 were observed. Intravenous CYT107 reversed sepsis-induced lymphopenia. However, compared to intramuscular CYT107 administration, it was associated with transient respiratory distress without long-term sequelae. Because of equivalent positive laboratory and clinical responses, more favorable pharmacokinetics, and better patient tolerability, intramuscular administration of CYT107 is preferable. Trial registration: Clinicaltrials.gov, NCT03821038. Registered 29 January 2019, https://clinicaltrials.gov/ct2/show/NCT03821038?term=NCT03821038&draw=2&rank=1 .

Letermovir potently inhibits the cytomegalovirus (CMV)-terminase complex. Letermovir primary prophylaxis given for the first 3 months after allogeneic hematopoietic cell transplantation (HCT) has been shown to reduce clinically significant CMV infection and is well tolerated. Until now, only case reports or small retrospective series have been published on the use of letermovir for a secondary prophylaxis (SP) of CMV infection or diseases after HCT. Here we report the outcome of 80 consecutive CMV-seropositive adult patients included in the French compassionate program and who received letermovir as a SP after at least 1 CMV episode (infection or disease) since HCT. Letermovir was initiated at a median of 170 (49 to 1829) days after transplant and given orally for a median of 118 (26 to 396) days at the usual daily dose of 480 mg once daily and adjusted to 240 mg once daily when coadministered with cyclosporine. The donors were seronegative in 53% of the cases. Fifty patients had a current or previous graft-versus-host disease (GVHD) and 14 had experienced CMV disease since transplant. Four (5.5%) patients developed CMV breakthrough infections (n = 1) or diseases (n = 3) after the initiation of letermovir. In 3 of these 4 patients, further investigation of virologic resistance showed a CMV UL56 mutation C325Y or W, conferring the high-level letermovir resistance. One or more adverse reactions were declared by the local investigator in 15 (19%) patients. Only 2 patients stopped letermovir SP because of an adverse reaction (pruritus, 1; cytopenia, 1). In our experience, letermovir given as a SP may prevent a new CMV reactivation in a high-risk patient population and can be administered for several weeks, providing a bridge between the pre-emptive or therapeutic treatment of a CMV episode and CMV-specific immune reconstitution, giving time for tapering immunosuppressants. Prospective studies are required to confirm these results.

The ability of pathogens to cause disease depends on their aptitude to escape the immune system. Type IV pili are extracellular filamentous virulence factors composed of pilin monomers and frequently expressed by bacterial pathogens. As such they are major targets for the host immune system. In the human pathogen Neisseria meningitidis, strains expressing class I pilins contain a genetic recombination system that promotes variation of the pilin sequence and is thought to aid immune escape. However, numerous hypervirulent clinical isolates express class II pilins that lack this property. This raises the question of how they evade immunity targeting type IV pili. As glycosylation is a possible source of antigenic variation it was investigated using top-down mass spectrometry to provide the highest molecular precision on the modified proteins. Unlike class I pilins that carry a single glycan, we found that class II pilins display up to 5 glycosylation sites per monomer on the pilus surface. Swapping of pilin class and genetic background shows that the pilin primary structure determines multisite glycosylation while the genetic background determines the nature of the glycans. Absence of glycosylation in class II pilins affects pilus biogenesis or enhances pilus-dependent aggregation in a strain specific fashion highlighting the extensive functional impact of multisite glycosylation. Finally, molecular modeling shows that glycans cover the surface of class II pilins and strongly decrease antibody access to the polypeptide chain. This strongly supports a model where strains expressing class II pilins evade the immune system by changing their sugar structure rather than pilin primary structure. Overall these results show that sequence invariable class II pilins are cloaked in glycans with extensive functional and immunological consequences.

OBJECTIVES: Mupirocin is the cornerstone of decolonization regimens, a successful strategy to prevent healthcare-associated staphylococcal infections. Several recent studies have reported alarming results: (i) an extending reservoir of mupA, the ancestral mobile resistance gene, among coagulase-negative staphylococci (CoNS); (ii) the emergence of a new resistance gene (mupB); and (iii) a growing number of mupirocin-resistant methicillin-resistant Staphylococcus aureus (MRSA), including highly pathogenic clones. We performed a nationwide prospective study in France to detect such trends among invasive staphylococci. METHODS: Between October 2011 and February 2012, 367 MRSA and 708 CoNS invasive isolates were collected from 37 hospitals and analysed centrally. Mupirocin MICs were determined using the broth microdilution method. mupA/B PCR was performed for resistant isolates (MIC >1 mg/L). Genetic relatedness between mupirocin-resistant MRSA isolates was determined by PFGE analysis and related isolates were tested by microarray. RESULTS: Among MRSA isolates 2.2% (n = 8) were classified as mupirocin resistant; 1.4% (n = 5) showing low-level resistance (MIC ≤256 mg/L) and 0.8% (n = 3) high-level resistance (MIC >256 mg/L). Only the latter isolates carried mupA. A clonal relationship was identified between two mupA-negative MRSA from the same hospital and three mupA-positive MRSA from three distant towns; these three isolates belonged to the Lyon clone. Mupirocin resistance was identified in 10.3% of CoNS, mainly highly resistant mupA-positive isolates (5.6%). The mupB gene was not detected in mupirocin-resistant MRSA or CoNS. CONCLUSIONS: This first large national study indicates the need for thorough epidemiological monitoring and a stewardship programme to prevent and detect mupirocin resistance in staphylococci.

BACKGROUND: There is no gold standard to diagnose septic shock-induced disseminated intravascular coagulation (DIC). The objective of our multicenter prospective study was to assess the performances of the different major scoring systems in terms of mortality prediction and DIC diagnosis. The JAAM-DIC 2016 score, the ISTH overt-DIC 2001 score, the associations of sepsis-induced coagulopathy (SIC) score with JAAM-DIC 2016 or ISTH overt-DIC scores were tested in patients within 12 h of their admission in ICU for septic shock (day 1) and at day 2. RESULTS: 582 patients were enrolled in the study. 182/567 (32.1%) were diagnosed with DIC according to ISTH overt-DIC score, and 193/561 (34.4%) according to JAAM-DIC score; 486/577 patients (84.2%) were diagnosed with a coagulopathy according to SIC score. A moderate concordance was observed between ISTH overt-DIC and JAAM-DIC [κ = 0.67 (0.60, 0.73), p < 0.001]. The delay of positivity of the scores for early DIC patients was not different between JAAM-DIC and ISTH overt-DIC scores. Although it was positive earlier, SIC score had worse diagnosis specificity, as 84.2% of the patients with septic shock were diagnosed with "coagulopathy". The specificity of SIC score alone to predict mortality was very low [0.18 (0.15; 0.22)], compared to the ones of JAAM-DIC score [0.71 (0.67; 0.75)], and of ISTH overt-DIC score [0.76 (0.72; 0.80)], p < 0.001. The sensitivity of SIC score to predict mortality was 0.95 [0.89; 0.98], and the ones of JAAM-DIC score and ISTH overt-DIC score were 0.61 [0.50; 0.70] and 0.68 [0.58; 0.77], respectively. There was no benefit in sensitivity and specificity in combining SIC score to JAAM-DIC score or to ISTH overt-DIC score, compared to JAAM-DIC score or ISTH overt-DIC score alone. CONCLUSIONS: Our data suggest that the added value of SIC score alone or combined with other scores is limited, and that both JAAM-DIC score and ISTH overt-DIC score can be used in septic shock patients. Trial registration clinicaltrial; Trial registration number: NCT02391792; Date of registration: 18/03/2015; URL of trial registry record: https://clinicaltrials.gov/ct2/show/NCT02391792?term=meziani&draw=4&rank=1.

PURPOSE: We aimed to determine whether interferon gamma-1b prevents hospital-acquired pneumonia in mechanically ventilated patients. METHODS: In a multicenter, placebo-controlled, randomized trial conducted in 11 European hospitals, we randomly assigned critically ill adults, with one or more acute organ failures, under mechanical ventilation to receive interferon gamma-1b (100 µg every 48 h from day 1 to 9) or placebo (following the same regimen). The primary outcome was a composite of hospital-acquired pneumonia or all-cause mortality on day 28. The planned sample size was 200 with interim safety analyses after enrolling 50 and 100 patients. RESULTS: The study was discontinued after the second safety analysis for potential harm with interferon gamma-1b, and the follow-up was completed in June 2022. Among 109 randomized patients (median age, 57 (41-66) years; 37 (33.9%) women; all included in France), 108 (99%) completed the trial. Twenty-eight days after inclusion, 26 of 55 participants (47.3%) in the interferon-gamma group and 16 of 53 (30.2%) in the placebo group had hospital-acquired pneumonia or died (adjusted hazard ratio (HR) 1.76, 95% confidence interval (CI) 0.94-3.29; P = 0.08). Serious adverse events were reported in 24 of 55 participants (43.6%) in the interferon-gamma group and 17 of 54 (31.5%) in the placebo group (P = 0.19). In an exploratory analysis, we found that hospital-acquired pneumonia developed in a subgroup of patients with decreased CCL17 response to interferon-gamma treatment. CONCLUSIONS: Among mechanically ventilated patients with acute organ failure, treatment with interferon gamma-1b compared with placebo did not significantly reduce the incidence of hospital-acquired pneumonia or death on day 28. Furthermore, the trial was discontinued early due to safety concerns about interferon gamma-1b treatment.

Integrons have played a major role in the rise and spread of multidrug resistance in Gram-negative pathogens and are nowadays commonplace among clinical isolates. These platforms capture, stockpile, and modulate the expression of more than 170 antimicrobial resistance cassettes (ARCs) against most clinically-relevant antibiotics. Despite their importance, our knowledge on their profile and resistance levels is patchy, because data is scattered in the literature, often reported in different genetic backgrounds and sometimes extrapolated from sequence similarity alone. Here we have generated a collection of 136 ARCs against 8 antibiotic families and disinfectants. Cassettes are cloned in a vector designed to mimic the genetic environment of a class 1 integron, and transformed in Escherichia coli. We have measured the minimal inhibitory concentration (MIC) to the most relevant molecules from each antibiotic family. With more than 500 MIC values, we provide an exhaustive and comparable quantitation of resistance conferred by ARCs. Our data confirm known resistance trends and profiles while revealing important differences among closely related genes. We have also detected genes that do not confer the expected resistance, to the point of challenging the role of the whole family of qac genes in resistance against disinfectants. Our work provides a detailed characterization of integron resistance genes at-a-glance.

BACKGROUND: Granulocyte-macrophage colony-stimulating factor (GM-CSF) and dysregulated myeloid cell responses are implicated in the pathophysiology and severity of COVID-19. METHODS: In this randomised, sequential, multicentre, placebo-controlled, double-blind study, adults aged 18-79 years (Part 1) or ≥70 years (Part 2) with severe COVID-19, respiratory failure and systemic inflammation (elevated C-reactive protein/ferritin) received a single intravenous infusion of otilimab 90 mg (human anti-GM-CSF monoclonal antibody) plus standard care (NCT04376684). The primary outcome was the proportion of patients alive and free of respiratory failure at Day 28. RESULTS: 67% who received placebo; the model-adjusted difference of 5.3% was not statistically significant (95% CI -0.8-11.4%, p=0.09). A nominally significant model-adjusted difference of 19.1% (95% CI 5.2-33.1%, p=0.009) was observed in the predefined 70-79 years subgroup, but this was not confirmed in Part 2 (n=350 randomised) where the model-adjusted difference was 0.9% (95% CI -9.3-11.2%, p=0.86). Compared with placebo, otilimab resulted in lower serum concentrations of key inflammatory markers, including the putative pharmacodynamic biomarker CC chemokine ligand 17, indicative of GM-CSF pathway blockade. Adverse events were comparable between groups and consistent with severe COVID-19. CONCLUSIONS: There was no significant difference in the proportion of patients alive and free of respiratory failure at Day 28. However, despite the lack of clinical benefit, a reduction in inflammatory markers was observed with otilimab, in addition to an acceptable safety profile.

OBJECTIVES: To explore candidate prognostic and predictive biomarkers identified in retrospective observational studies (interleukin-6, C-reactive protein, lactate dehydrogenase, ferritin, lymphocytes, monocytes, neutrophils, d-dimer, and platelets) in patients with coronavirus disease 2019 pneumonia after treatment with tocilizumab, an anti-interleukin-6 receptor antibody, using data from the COVACTA trial in patients hospitalized with severe coronavirus disease 2019 pneumonia. DESIGN: Exploratory analysis from a multicenter, randomized, double-blind, placebo-controlled, phase 3 trial. SETTING: Hospitals in North America and Europe. PATIENTS: Adults hospitalized with severe coronavirus disease 2019 pneumonia receiving standard care. INTERVENTION: Randomly assigned 2:1 to IV tocilizumab 8 mg/kg or placebo. MEASUREMENTS AND MAIN RESULTS: Candidate biomarkers were measured in 295 patients in the tocilizumab arm and 142 patients in the placebo arm. Efficacy outcomes assessed were clinical status on a seven-category ordinal scale (1, discharge; 7, death), mortality, time to hospital discharge, and mechanical ventilation (if not receiving it at randomization) through day 28. Prognostic and predictive biomarkers were evaluated continuously with proportional odds, binomial or Fine-Gray models, and additional sensitivity analyses. Modeling in the placebo arm showed all candidate biomarkers except lactate dehydrogenase and d-dimer were strongly prognostic for day 28 clinical outcomes of mortality, mechanical ventilation, clinical status, and time to hospital discharge. Modeling in the tocilizumab arm showed a predictive value of ferritin for day 28 clinical outcomes of mortality (predictive interaction, p = 0.03), mechanical ventilation (predictive interaction, p = 0.01), and clinical status (predictive interaction, p = 0.02) compared with placebo. CONCLUSIONS: Multiple biomarkers prognostic for clinical outcomes were confirmed in COVACTA. Ferritin was identified as a predictive biomarker for the effects of tocilizumab in the COVACTA patient population; high ferritin levels were associated with better clinical outcomes for tocilizumab compared with placebo at day 28.

Human cytomegalovirus (HCMV) is one of the main causes of serious complications in immunocompromised patients and after congenital infection. There are currently drugs available to treat HCMV infection, targeting viral polymerase, whose use is complicated by toxicity and the emergence of resistance. Maribavir and letermovir are the latest antivirals to have been developed with other targets. The approval of letermovir represents an important innovation for CMV prevention in hematopoietic stem cell transplant recipients, whereas maribavir allowed improving the management of refractory or resistant infections in transplant recipients. However, in case of multidrug resistance or for the prevention and treatment of congenital CMV infection, finding new antivirals or molecules able to inhibit CMV replication with the lowest toxicity remains a critical need. This review presents a range of molecules known to be effective against HCMV. Molecules with a direct action against HCMV include brincidofovir, cyclopropavir and anti-terminase benzimidazole analogs. Artemisinin derivatives, quercetin and baicalein, and anti-cyclooxygenase-2 are derived from natural molecules and are generally used for different indications. Although they have demonstrated indirect anti-CMV activity, few clinical studies were performed with these compounds. Immunomodulating molecules such as leflunomide and everolimus have also demonstrated indirect antiviral activity against HCMV and could be an interesting complement to antiviral therapy. The efficacy of anti-CMV immunoglobulins are discussed in CMV congenital infection and in association with direct antiviral therapy in heart transplanted patients. All molecules are described, with their mode of action against HCMV, preclinical tests, clinical studies and possible resistance. All these molecules have shown anti-HCMV potential as monotherapy or in combination with others. These new approaches could be interesting to validate in clinical trials.

Background: In COVACTA, a randomised, placebo-controlled trial in patients hospitalised with coronavirus disease-19 (COVID-19), tocilizumab did not improve 28-day mortality, but shortened hospital and intensive care unit stay. Longer-term effects of tocilizumab in patients with COVID-19 are unknown. Therefore, the efficacy and safety of tocilizumab in COVID-19 beyond day 28 and its impact on Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) clearance and antibody response in COVACTA were investigated. Methods: = 452) between April 3, 2020 and May 28, 2020 were randomly assigned (2:1) to double-blind intravenous tocilizumab or placebo and assessed for efficacy and safety through day 60. Assessments included mortality, time to hospital discharge, SARS-CoV-2 viral load in nasopharyngeal swab and serum samples, and neutralising anti-SARS-CoV-2 antibodies in serum. ClinicalTrials.gov registration: NCT04320615. Findings: By day 60, 24·5% (72/294) of patients in the tocilizumab arm and 25·0% (36/144) in the placebo arm died (weighted difference -0·5% [95% CI -9·1 to 8·0]), and 67·0% (197/294) in the tocilizumab arm and 63·9% (92/144) in the placebo arm were discharged from the hospital. Serious infections occurred in 24·1% (71/295) of patients in the tocilizumab arm and 29·4% (42/143) in the placebo arm. Median time to negative reverse transcriptase-quantitative polymerase chain reaction result in nasopharyngeal/oropharyngeal samples was 15·0 days (95% CI 14·0 to 21·0) in the tocilizumab arm and 21·0 days (95% CI 14·0 to 28·0) in the placebo arm. All tested patients had positive test results for neutralising anti-SARS-CoV-2 antibodies at day 60. Interpretation: There was no mortality benefit with tocilizumab through day 60. Tocilizumab did not impair viral clearance or host immune response, and no new safety signals were observed. Future investigations may explore potential biomarkers to optimize patient selection for tocilizumab treatment and combination therapy with other treatments. Funding: F. Hoffmann-La Roche Ltd and the US Department of Health and Human Services, Office of the Assistant Secretary for Preparedness and Response, Biomedical Advanced Research and Development Authority, under OT number HHSO100201800036C.

copies, associated with lower MICs (8 to 32 mg/liter) and low to moderate generation time increases. Despite these differences, whole-genome sequencing allowed us to determine that all isolates, including the susceptible one isolated before LZD treatment, belonged to the same lineage. In conclusion, LZD resistance can emerge rapidly in CF patients and persist without linezolid selective pressure in colonizing MRSA strains belonging to the same lineage.

Integrons are bacterial genetic elements that capture, stockpile, and modulate the expression of genes encoded in integron cassettes. Mobile integrons (MIs) are borne on plasmids, acting as a vehicle for hundreds of antimicrobial resistance genes among key pathogens. These elements also carry gene cassettes of unknown function ( gcu s) whose role and adaptive value remain unexplored. In this work, we show that gcu s encode phage resistance systems, many of which are newly discovered. Bacteriophage resistance integron cassettes (BRiCs) can be combined and mixed with resistance cassettes to produce multiphage or drug and phage resistance. The fitness costs of BRiCs are variable and dependent on the genetic context and can be modulated by changing the order of cassettes in the array. Hence, MIs act as highly mobile, low-cost defense islands.

BACKGROUND AND AIMS: First generation protease inhibitors (PI) with peg-interferon (PEG-IFN) and ribavirin (RBV) have been the only therapy available for hepatitis C virus (HCV) genotype 1 infection in most countries for 3 years. We have investigated the efficacy and tolerance of this triple therapy in transplanted patients experiencing a recurrence of HCV infection on the liver graft. PATIENTS: This cohort study enrolled 81 liver transplant patients (Male: 76%, mean age: 55.8±9.7 years) with severe HCV recurrence (F3 or F4: n = 34 (42%), treatment experienced: n = 44 (54%)), treated with boceprevir (n = 36; 44%) or telaprevir (n = 45; 56%). We assessed the percentages of patients with sustained virological responses 24 weeks after therapy (SVR24), and safety. RESULTS: The SVR24 rate was 47% (telaprevir: 42%; boceprevir: 53%, P = ns). At baseline, a normal bilirubin level (p = 0.0145) and albumin level >35g/L (p = 0.0372) and an initial RBV dosage of ≥800 mg/day (p = 0.0033) predicted SVR24. During treatment, achieving an early virological response after 12 weeks was the strongest independent factor to predict SVR24 (p<0.0001). A premature discontinuation of anti-HCV therapy due to a serious adverse event (SAE) was observed in 22 patients (27%). Hematological toxicity, infections and deaths were observed in 95%, 28% and 7% of patients, respectively. A history of post-LT antiviral therapy and thrombocytopenia (<50G/L) during treatment were both independent predictors of the occurrence of infections or SAE (p = 0.0169 and p = 0.011). CONCLUSIONS: The use of first generation PI after liver transplantation enabled an SVR24 rate of 47% in genotype 1 patients, but induced a high rate of SAE. The identification of predictive factors for a response to treatment, and the occurrence of SAE, have enabled us to establish limits for the use of this anti-HCV therapy in the transplant setting.