Clinical and bacteriological specificities of Escherichia coli bloodstream infections from biliary portal of entries.

BACKGROUND: Escherichia coli is frequently responsible for bloodstream infections (BSI). Among digestive BSI, biliary infections appear to be less severe. Respective roles of host factors, bacterial determinants (phylogroups, virulence and antibiotic resistance) and portal of entry on outcome are unknown. METHODS: Clinical characteristics and prognosis of 770 episodes of E. coli BSI were analyzed and isolates sequenced (Illumina technology) comparing phylogroups, MLST, virulence and resistance gene content. BSI isolates were compared with 362 commensal E. coli from healthy subjects. RESULTS: Among 770 episodes, 135 were biliary, 156 non-biliary digestive and 479 urinary. Compared to urinary, BSI of digestive origin occurred significantly more in men, comorbid and immunocompromised patients. Digestive portal of entry was significantly associated with septic shock and death. Among digestive infections, patients with biliary infections were dies less (P=0.032), despite comparable initial severity. Biliary E. coli resembled commensals (phylogroup distribution, ST group and few virulence-associated genes) whereas non-biliary digestive and urinary strains carried many virulence-associated genes. CONCLUSIONS: E. coli strains responsible for biliary infections exhibit commensal characteristics and are associatedd with lower mortality rates, despite similar initial severity than other digestive BSI. Biliary drainage in addition to antibiotics in the management of biliary infections may explain improved outcome.

SARS-CoV-2 Omicron BA.1 breakthrough infection drives late remodeling of the memory B cell repertoire in vaccinated individuals.

How infection by a viral variant showing antigenic drift impacts a preformed mature human memory B cell (MBC) repertoire remains an open question. Here, we studied the MBC response up to 6 months after SARS-CoV-2 Omicron BA.1 breakthrough infection in individuals previously vaccinated with three doses of the COVID-19 mRNA vaccine. Longitudinal analysis, using single-cell multi-omics and functional analysis of monoclonal antibodies from RBD-specific MBCs, revealed that a BA.1 breakthrough infection mostly recruited pre-existing cross-reactive MBCs with limited de novo response against BA.1-restricted epitopes. Reorganization of clonal hierarchy and new rounds of germinal center reactions, however, combined to maintain diversity and induce progressive maturation of the MBC repertoire against common Hu-1 and BA.1, but not BA.5-restricted, SARS-CoV-2 Spike RBD epitopes. Such remodeling was further associated with a marked improvement in overall neutralizing breadth and potency. These findings have fundamental implications for the design of future vaccination booster strategies.

Qualitative monitoring of SARS-CoV-2 mRNA vaccination in humans using droplet microfluidics.

SARS-CoV-2 mRNA vaccination generates protective B cell responses targeting the SARS-CoV-2 spike glycoprotein. Whereas anti-spike memory B cell responses are long lasting, the anti-spike humoral antibody response progressively wanes, making booster vaccinations necessary for maintaining protective immunity. Here, we qualitatively investigated the plasmablast responses by measuring from single cells within hours of sampling the affinity of their secreted antibody for the SARS-CoV-2 spike receptor binding domain (RBD) in cohorts of BNT162b2-vaccinated naive and COVID-19-recovered individuals. Using a droplet microfluidic and imaging approach, we analyzed more than 4,000 single IgG-secreting cells, revealing high interindividual variability in affinity for RBD, with variations over 4 logs. High-affinity plasmablasts were induced by BNT162b2 vaccination against Hu-1 and Omicron RBD but disappeared quickly thereafter, whereas low-affinity plasmablasts represented more than 65% of the plasmablast response at all time points. Our droplet-based method thus proves efficient at fast and qualitative immune monitoring and should be helpful for optimization of vaccination protocols.

Human type I IFN deficiency does not impair B cell response to SARS-CoV-2 mRNA vaccination.

Inborn and acquired deficits of type I interferon (IFN) immunity predispose to life-threatening COVID-19 pneumonia. We longitudinally profiled the B cell response to mRNA vaccination in SARS-CoV-2 naive patients with inherited TLR7, IRF7, or IFNAR1 deficiency, as well as young patients with autoantibodies neutralizing type I IFNs due to autoimmune polyendocrine syndrome type-1 (APS-1) and older individuals with age-associated autoantibodies to type I IFNs. The receptor-binding domain spike protein (RBD)-specific memory B cell response in all patients was quantitatively and qualitatively similar to healthy donors. Sustained germinal center responses led to accumulation of somatic hypermutations in immunoglobulin heavy chain genes. The amplitude and duration of, and viral neutralization by, RBD-specific IgG serological response were also largely unaffected by TLR7, IRF7, or IFNAR1 deficiencies up to 7 mo after vaccination in all patients. These results suggest that induction of type I IFN is not required for efficient generation of a humoral response against SARS-CoV-2 by mRNA vaccines.

Human anti-smallpox long-lived memory B cells are defined by dynamic interactions in the splenic niche and long-lasting germinal center imprinting.

Memory B cells (MBCs) can persist for a lifetime, but the mechanisms that allow their long-term survival remain poorly understood. Here, we isolated and analyzed human splenic smallpox/vaccinia protein B5-specific MBCs in individuals who were vaccinated more than 40 years ago. Only a handful of clones persisted over such an extended period, and they displayed limited intra-clonal diversity with signs of extensive affinity-based selection. These long-lived MBCs appeared enriched in a CD21hiCD20hi IgG+ splenic B cell subset displaying a marginal-zone-like NOTCH/MYC-driven signature, but they did not harbor a unique longevity-associated transcriptional or metabolic profile. Finally, the telomeres of B5-specific, long-lived MBCs were longer than those in patient-paired naive B cells in all the samples analyzed. Overall, these results imply that separate mechanisms such as early telomere elongation, affinity selection during the contraction phase, and access to a specific niche contribute to ensuring the functional longevity of MBCs.

Clinical and microbiological characteristics of reflux cholangitis following bilio-enteric anastomosis.

Twenty-five patients with reflux cholangitis (RC) defined as acute cholangitis (AC) with normal abdominal imaging occurring > 3 months after bilioenteric anastomosis were described and compared to 116 AC patients with biliary obstruction (tumoral, lithiasis). RC episodes occurred a median 4.5 months after surgery; 18 (72%) had recurrent RC (n ≥ 3). RC episodes were less severe than obstructive AC; the outcome was favorable with short antibiotic courses and no selection of antibiotic-resistance. However, multiple recurrent RC occurred in 20 patients (80%). Prophylactic or pre-emptive antibiotics were successful in 3 and 11 patients. Revision surgery for jejunal loop lengthening was successful in 2/4 patients.

Immune Responses after a Third Dose of mRNA Vaccine Differ in Virus-Naive versus SARS-CoV-2- Recovered Dialysis Patients.

BACKGROUND AND OBJECTIVES: After two doses of mRNA vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), patients on dialysis show a defective humoral response, but a third dose could increase anti-SARS-CoV-2 spike IgG titers. Responses could be different in virus-naive and SARS-CoV-2-recovered patients on dialysis. However, characterization of memory B cell response after three doses is lacking. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We evaluated the dynamics of antireceptor binding domain IgG titers and antireceptor binding domain memory B cells until 6 months after two and three doses (administered within 6 months after the second dose) of mRNA vaccine in SARS-CoV-2-recovered and virus-naive dialysis populations. Results were analyzed by ordinary one-way ANOVA, the Kruskal-Wallis test, or the Wilcoxon matched-pairs test as appropriate. RESULTS: In total, 108 individuals (59 patients on dialysis and 49 controls) were included. In virus-naive patients on dialysis, antireceptor binding domain IgG response was quantitatively lower after two doses compared with healthy controls, but IgG titers increased by three-fold after three doses (P=0.008). In SARS-CoV-2-recovered patients on dialysis, antireceptor binding domain IgG titers after two doses were significantly higher compared with virus-naive patients on dialysis but did not significantly increase after a third dose. Regarding memory B cell response, we detected receptor binding domain-specific memory B cells at similar proportions in virus-naive patients on dialysis and vaccinated controls after two doses. Moreover, a strong receptor binding domain-specific memory B cell expansion was observed after the third dose in virus-naive patients on dialysis (5.5-fold; P<0.001). However, in SARS-CoV-2-recovered patients on dialysis, antireceptor binding domain memory B cells remained unchanged after the third dose. CONCLUSIONS: The third dose of mRNA vaccine given within 6 months after the second dose boosts serologic and memory response in virus-naive patients but not in SARS-CoV-2-recovered patients on dialysis. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: COVID-19: SARS-CoV-2 Specific Memory B and T-CD4+ Cells (MEMO-COV2), NCT04402892.

High-affinity autoreactive plasma cells disseminate through multiple organs in patients with immune thrombocytopenic purpura.

The major therapeutic goal for immune thrombocytopenic purpura (ITP) is to restore normal platelet counts using drugs to promote platelet production or by interfering with mechanisms responsible for platelet destruction. Eighty percent of patients with ITP possess anti-integrin αIIbß3 IgG autoantibodies that cause platelet opsonization and phagocytosis. The spleen is considered the primary site of autoantibody production by autoreactive B cells and platelet destruction. The immediate failure in approximately 50% of patients to recover a normal platelet count after anti-CD20 rituximab-mediated B cell depletion and splenectomy suggests that autoreactive, rituximab-resistant, IgG-secreting B cells (IgG-SCs) reside in other anatomical compartments. We analyzed more than 3,300 single IgG-SCs from spleen, bone marrow, and/or blood of 27 patients with ITP, revealing high interindividual variability in affinity for αIIbß3, with variations over 3 logs. IgG-SC dissemination and range of affinities were, however, similar for each patient. Longitudinal analysis of autoreactive IgG-SCs upon treatment with the anti-CD38 mAb daratumumab demonstrated variable outcomes, from complete remission to failure with persistence of high-affinity anti-αIIbß3 IgG-SCs in the bone marrow. This study demonstrates the existence and dissemination of high-affinity autoreactive plasma cells in multiple anatomical compartments of patients with ITP that may cause the failure of current therapies.

Analysis of mRNA vaccination-elicited RBD-specific memory B cells reveals strong but incomplete immune escape of the SARS-CoV-2 Omicron variant.

The SARS-CoV-2 Omicron variant can escape neutralization by vaccine-elicited and convalescent antibodies. Memory B cells (MBCs) represent another layer of protection against SARS-CoV-2, as they persist after infection and vaccination and improve their affinity. Whether MBCs elicited by mRNA vaccines can recognize the Omicron variant remains unclear. We assessed the affinity and neutralization potency against the Omicron variant of several hundred naturally expressed MBC-derived monoclonal IgG antibodies from vaccinated COVID-19-recovered and -naive individuals. Compared with other variants of concern, Omicron evaded recognition by a larger proportion of MBC-derived antibodies, with only 30% retaining high affinity against the Omicron RBD, and the reduction in neutralization potency was even more pronounced. Nonetheless, neutralizing MBC clones could be found in all the analyzed individuals. Therefore, despite the strong immune escape potential of the Omicron variant, these results suggest that the MBC repertoire generated by mRNA vaccines still provides some protection against the Omicron variant in vaccinated individuals.

Specificities of acute cholangitis in patients with cancer: a retrospective comparative study of 130 episodes.

Pancreatic and biliary duct cancers are increasing causes of acute cholangitis (AC). We retrospectively characterize 81 cancer-associated cholangitis (CAC) compared to 49 non-cancer-associated cholangitis (NCAC). Clinical and biological presentations were similar. However, in CAC, antibiotic resistance and inadequate empirical antibiotic therapy were more frequent; more patients required ≥ 2 biliary drainages; and mortality at day 28 was higher than in NCAC. Death was associated with initial severity and CAC in a multivariate analysis. Cholangitis associated with pancreatic or biliary duct cancers requires specific empirical antimicrobial therapy; early use of biliary drainage may improve outcomes.

Primary immune thrombocytopenia in very elderly patients: particularities in presentation and management: results from the prospective CARMEN-France Registry.

Data about the presentation and the management of primary immune thrombocytopenia (ITP) in very elderly patients (VEPs; aged ≥80 years) are lacking. The aim of the present study was to describe ITP in this subgroup. The data source was the prospective CARMEN-France registry. Patients included between 2013 and 2018 were selected. ITP presentation and management in VEPs was compared to elderly patients (EPs; aged 65-79 years). We assessed factors associated with bleeding at ITP onset in VEPs. Of 541 patients, 184 were included: 87 in the VEP group and 97 in the EP group. The mean age was 85·7 years in the VEP group. Comorbidities were more frequent in the VEP group (67·4% vs. 47·9%). The median platelet count at ITP onset was similar but severe bleeding tended to be more frequent in VEPs (10·3% vs. 4·1%, P = 0·1) as well as mortality. Exposure to ITP drugs, response to first-line treatment, need of second-line treatment, evolution towards persistency, occurrence of bleeding, infection and thrombosis did not differ between groups. In VEPs, factors associated to bleeding were female sex [odds ratio (OR) 4·75, 95% confidence interval (CI) 1·31-17·32] and platelet count of <20 × 109 /l (OR 10·05, 95% CI 4·83-67·39). Exposure to anticoagulants was strongly associated with severe bleeding (OR 7·61, 95% CI 1·77-32·83).

mRNA vaccination of naive and COVID-19-recovered individuals elicits potent memory B cells that recognize SARS-CoV-2 variants.

In addition to serum immunoglobulins, memory B cell (MBC) generation against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is another layer of immune protection, but the quality of MBC responses in naive and coronavirus disease 2019 (COVID-19)-recovered individuals after vaccination remains ill defined. We studied longitudinal cohorts of naive and disease-recovered individuals for up to 2 months after SARS-CoV-2 mRNA vaccination. We assessed the quality of the memory response by analysis of antibody repertoires, affinity, and neutralization against variants of concern (VOCs) using unbiased cultures of 2,452 MBCs. Upon boosting, the MBC pool of recovered individuals expanded selectively, matured further, and harbored potent neutralizers against VOCs. Although naive individuals had weaker neutralizing serum responses, half of their RBD-specific MBCs displayed high affinity toward multiple VOCs, including delta (B.1.617.2), and one-third retained neutralizing potency against beta (B.1.351). Our data suggest that an additional challenge in naive vaccinees could recall such affinity-matured MBCs and allow them to respond efficiently to VOCs.

Rituximab-resistant splenic memory B cells and newly engaged naive B cells fuel relapses in patients with immune thrombocytopenia.

Rituximab (RTX), an antibody targeting CD20, is widely used as a first-line therapeutic strategy in B cell-mediated autoimmune diseases. However, a large proportion of patients either do not respond to the treatment or relapse during B cell reconstitution. Here, we characterize the cellular basis responsible for disease relapse in secondary lymphoid organs in humans, taking advantage of the opportunity offered by therapeutic splenectomy in patients with relapsing immune thrombocytopenia. By analyzing the B and plasma cell immunoglobulin gene repertoire at bulk and antigen-specific single-cell level, we demonstrate that relapses are associated with two responses coexisting in germinal centers and involving preexisting mutated memory B cells that survived RTX treatment and naive B cells generated upon reconstitution of the B cell compartment. To identify distinctive characteristics of the memory B cells that escaped RTX-mediated depletion, we analyzed RTX refractory patients who did not respond to treatment at the time of B cell depletion. We identified, by single-cell RNA sequencing (scRNA-seq) analysis, a population of quiescent splenic memory B cells that present a unique, yet reversible, RTX-shaped phenotype characterized by down-modulation of B cell-specific factors and expression of prosurvival genes. Our results clearly demonstrate that these RTX-resistant autoreactive memory B cells reactivate as RTX is cleared and give rise to plasma cells and further germinal center reactions. Their continued surface expression of CD19 makes them efficient targets for current anti-CD19 therapies. This study thus identifies a pathogenic contributor to autoimmune diseases that can be targeted by available therapeutic agents.

Temocillin as an alternative treatment for acute bacterial cholangitis: a retrospective microbiology susceptibility-based study of 140 episodes.

With rising antibiotic resistance, alternatives to carbapenems are needed for acute cholangitis (AC). Temocillin reaches high biliary concentrations with limited impact on microbiota. We retrospectively included 140 AC episodes and assessed the efficacy of temocillin using microbiology susceptibility testing from blood cultures. Considering all bacteria collected by episode, resistance to temocillin, PIP/TAZ and 3GC occurred in 27/140 (26%), 32 (22.8%) and 31 (22%) episodes, respectively (p = 0.7). After documentation, temocillin could have spared PIP/TAZ or carbapenems in 14/26 and 4/11 episodes. Temocillin may constitute an alternative treatment after microbiological documentation by sparing carbapenems and/or PIP/TAZ, but not as an empirical therapeutic option.

Maturation and persistence of the anti-SARS-CoV-2 memory B cell response.

Memory B cells play a fundamental role in host defenses against viruses, but to date, their role has been relatively unsettled in the context of SARS-CoV-2. We report here a longitudinal single-cell and repertoire profiling of the B cell response up to 6 months in mild and severe COVID-19 patients. Distinct SARS-CoV-2 spike-specific activated B cell clones fueled an early antibody-secreting cell burst as well as a durable synchronous germinal center response. While highly mutated memory B cells, including pre-existing cross-reactive seasonal Betacoronavirus-specific clones, were recruited early in the response, neutralizing SARS-CoV-2 RBD-specific clones accumulated with time and largely contributed to the late, remarkably stable, memory B cell pool. Highlighting germinal center maturation, these cells displayed clear accumulation of somatic mutations in their variable region genes over time. Overall, these findings demonstrate that an antigen-driven activation persisted and matured up to 6 months after SARS-CoV-2 infection and may provide long-term protection.

Zika virus infection: report of the first imported cases in a Paris travel centre.

We describe characteristics of 17 patients with a Zika virus (ZIKV) infection seen in a Travel Center in Paris during the 4 months following the WHO alert on ZIKV. Sixteen were imported cases, including 13 from the Caribbean. One was a women living in Paris infected through sexual transmission. One case was a pregnant woman. All cases were symptomatic with fever, fatigue and cutaneous rash in 15/17, 13/17, and 16/17, respectively. Leucopenia was observed in 6/17, thrombopenia in 2/17. Diagnosis was confirmed by ZIKV RT-PCR (plasma: 12/17; urine 15/17) or detection of ZIKV IgM (2/17). Two patients were hospitalized but all evolved well.