Antibody response after second BNT162b2 dose in allogeneic HSCT recipients

No abstract

The aim of this study was to evaluate the prevalence of resistance to macrolide-lincosamide-streptogramin (MLS) antibiotics as well as to assess the molecular basis of this resistance amongst 72 Staphylococcus saprophyticus urinary isolates collected from 2005 to 2009 in University Hospital of Caen (France). Of the 72 strains studied, 33 (45.8%) were resistant to at least one MLS antibiotic, including 24 (72.7%) with an M phenotype, 5 (15.2%) with an inducible MLS(B) phenotype, 3 (9.1%) with a combined M+L phenotype and 1 (3.0%) with an L phenotype. All isolates were susceptible to the combination of streptogramins A and B. The resistance genes erm(A), erm(B), erm(C), msr(A) and lnu(A) were detected alone in 0, 0, 5 (15.2%), 24 (72.7%) and 1 (3.0%) of the 33 MLS-resistant isolates, respectively, whereas 2 strains (6.1%) were positive for both msr(A) and lnu(A). All msr(A)-positive isolates exhibited an M phenotype, whereas all five erm(C)-positive and all three lnu(A)-positive strains displayed, respectively, an inducible MLS(B) phenotype and an L phenotype with a positive Hodge test. Plasmid analysis indicated that erm(C) and lnu(A) genes were borne by small-size plasmids (ca. 2.5 kb), whereas larger plasmids (30-90 kb) harboured msr(A). In conclusion, these findings show a high prevalence of MLS resistance in S. saprophyticus, which was mainly associated with the presence of the msr(A) gene. Since S. saprophyticus colonises the gastrointestinal tract, it may constitute an unexpected reservoir for MLS resistance genes, in particular msr(A), amongst coagulase-negative staphylococci.

Hematopoietic stem cell transplant (HSCT) recipients are at high-risk for severe COVID-19 and have altered immune responses to vaccination. We sought to evaluate the dynamics of immune response to BNT162b2 mRNA vaccine in HSCT recipients. We systematically proposed vaccination with BNT162b2 to HSCT recipients and gave a third vaccine dose to those showing titers of IgG(S-RBD) below 4160 AU/mL 1 month following the second dose. We then quantified anti-SARS-CoV-2 antibodies dynamics in 133 of these HSCT recipients (88 after two and 45 after three vaccine doses) 6 months after the first vaccine dose. Mean IgG(S-RBD) titer at 6 months was significantly lower than the peak value measured 1 month after a second (p < 0.001) or third (p < 0.01) vaccine dose. IgG(S-RBD) titers at 6 months were strongly correlated to peak values (p < 0.001) and a peak titer above 10,370 AU/mL predicted persistent protection at 6 months. Seventy-two percent (96/133) of patients retained protective antibody levels at 6 months. Immunosuppressive drugs and low lymphocyte counts in peripheral blood correlated with lower IgG(S-RBD) titers at 6 months. Four patients (3%) developed PCR-documented SARS-CoV-2 infection and one died.