Cross neutralization of SARS‐CoV‐2 omicron subvariants after repeated doses of COVID‐19 mRNA vaccines

We have measured the humoral response to messenger RNA (mRNA) vaccines in COVID-19 naïve and convalescent individuals. Third doses of mRNA COVID-19 vaccines induced a significant increase in potency and breadth of neutralization against SARS-CoV-2 variants of concern (VoC) including Omicron subvariants BA.1, BA.2, and BA.2.12.1, that were cross-neutralized at comparable levels and less for BA.4/5. This booster effect was especially important in naïve individuals that only after the third dose achieved a level that was comparable with that of vaccinated COVID-19 convalescents except for BA.4/5. Avidity of RBD-binding antibodies was also significantly increased in naïve individuals after the third dose, indicating an association between affinity maturation and cross neutralization of VoC. These results suggest that at least three antigenic stimuli by infection or vaccination with ancestral SARS-CoV-2 sequences are required to induce high avidity cross-neutralizing antibodies. Nevertheless, the circulation of new subvariants such as BA.4/5 with partial resistance to neutralization will have to be closely monitored and eventually consider for future vaccine developments

Genotypic and Phenotypic Characteristics of Staphylococcus aureus Prosthetic Joint Infections: Insight on the Pathogenesis and Prognosis of a Multicenter Prospective Cohort

Background. Staphylococcus aureus is the leading cause of prosthetic joint infection (PJI). Beyond the antibiogram, little attention has been paid to the influence of deep microbiological characteristics on patient prognosis. Our aim was to investigate whether microbiological genotypic and phenotypic features have a significant influence on infection pathogenesis and patient outcome.Methods. A prospective multicenter study was performed, including all S. aureus PJIs (2016-2017). Clinical data and phenotypic (agr functionality, beta-hemolysis, biofilm formation) and genotypic characteristics of the strains were collected. Biofilm susceptibility to antimicrobials was investigated (minimal biofilm eradication concentration [MBEC] assay).Results. Eighty-eight patients (39.8% men, age 74.7 +/- 14.1 years) were included. Forty-five had early postoperative infections (EPIs), 21 had chronic infections (CPIs), and 19 had hematogenous infections (HIs). Twenty (22.7%) were caused by methicillin-resistant S. aureus. High genotypic diversity was observed, including 16 clonal complexes (CCs), with CC5 being the most frequent (30.7%). agr activity was greater in EPI than CPI (55.6% vs 28.6%; P = .041). Strains causing EPI were phenotypically and genotypically similar, regardless of symptom duration. Treatment failure (36.5%) occurred less frequently among cases treated with implant removal. In cases treated with debridement and implant retention, there were fewer failures among those who received combination therapy with rifampin. No genotypic or phenotypic characteristics predicted failure, except vancomycin minimal inhibitory concentration >= 1.5 mg/L (23.1% failure vs 3.4%; P = .044). MBEC(50 )was >128 mg/L for all antibiotics tested and showed no association with prognosis.Conclusions. S. aureus with different genotypic backgrounds is capable of causing PJI, showing slight differences in clinical presentation and pathogenesis. No major microbiological characteristics were observed to influence the outcome, including MBEC

Hip and Knee Section, Treatment, Debridement and Retention of Implant: Proceedings of International Consensus on Orthopedic Infections

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