Long-term transition of antibody titers in healthcare workers following the first to fourth doses of mRNA COVID-19 vaccine: Comparison of two automated SARS-CoV-2 immunoassays.

Anti-spike receptor binding domain (S-RBD) antibody against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which best correlates with virus-neutralizing antibody is useful for estimating the period of protection and identifying the timing of additional booster doses. Long-term transition of the S-RBD antibody titer and the antibody responses among healthy individuals remain unclear. In the present study, therefore, we monitored the S-RBD antibody titers of 16 healthcare workers every 4 weeks for 76 weeks after vaccination with a fourth dose of mRNA-1273 (Moderna) following three doses of BNT162b2 (Pfizer/BioNTech) using two commercial automated immunoassays (Roche and Abbott). Two antibody responses to the vaccine were similar with an up-down change before and after the second (weeks 3), third (weeks 40) and fourth (week 72) vaccinations, but the titer did not fall below the assay's positivity threshold in any individual. The peak level of the geometric mean titer (GMT) in the Roche assay was highest after the third vaccination, and that in Abbott assay was highest after the fourth vaccination but almost equal to that after the third vaccination. Both the geometric mean fold rise (GMFR) demonstrated by the Roche and Abbott assays were highest after the third vaccination. Antibody titers determined by the Roche and Abbott assays showed a positive strong correlation (correlation coefficient: 0.70 to 0.99), but the ratio (Roche/Abbott) of antibodies demonstrated by both assays increased 0.46- to 8.26-fold between weeks 3 and 76. These findings will be helpful for clinicians when interpreting results for SARS-CoV-2 antibody levels and considering future vaccination strategies.

[Comparison of PVL-producing MRSA Showing POT Type 106-77-113 and POT Type 106-255-121 Detected in Materials Derived from Patients with Skin Infections].

Methicillin-resistant Staphylococcus aureus (MRSA) strains showing POT type 106-77-113 have been associated with USA300. Additionally, many strains produce Panton-Valentine Leukocidin (PVL). Until 2018, 106-77-113 was the most dominant POT-type PVL-producing bacteria isolated in our hospital; however, in 2018, one strain with POT type 106-255-121 was isolated, and thereafter, since 2019, an increasing trend towards isolation of this strain has been observed. In this study, we compared two PVL-producing strains detected in skin infections-derived materials from outpatients during the three-year period between 2019 and 2021 through genetic analysis using next-generation sequencers. Eight, each of POT types 106-77-113 (POT-A) and 106-255-121 (POT-B), strains were included in this study, and PVL productivity, drug susceptibility, multi-locus sequencing typing (MLST), and resistance genes and virulence genes were detected. Both the groups shared the same MLST profile (3-3-1-1-4-4-3), but a single nucleotide mutation of ARCC was detected in POT-B type strain, which was determined to be similar to ST 8 of POT-A and POT-B type strains. Only POT-B type strains harbored aac(6')-aph(2″) and erm(A) genes, consistent with the results of drug susceptibility tests. All the strains were resistant to GM and CAM and were positive to D-zone test. On the other hand, the POT-A strains were sensitive to GM, and 7 of 8 strains were sensitive to CLDM and MINO. However, one POT-A type strain was found to harbor erm(C), tet(K), and tet(M) genes and was resistant to CAM, CLDM, and MINO. Both groups of isolates harbored 17 genes including ACME, lukF-PV, and LukS-PV, and no difference in pathogenicity was observed. In our hospital, one strain of POT type 106-255-121 was isolated for the first time in 2018, and the number of isolates of this type has been increasing since then. The present study confirms that POT type 106-255-121 strains have the same virulence as POT type 106-77-113 strains have and have also acquired a drug resistance gene.

Persistence of left atrial abnormalities despite left atrial volume normalization after successful ablation of atrial fibrillation.

BACKGROUND: Left atrial volume index (LAVI) of >34 mL/m2 is the cutoff value for identifying an enlarged left atrium. The definition of left atrial (LA) reverse remodeling after atrial fibrillation (AF) ablation is undetermined. We hypothesized that patients with LA dilatation who achieve normal LA volume (LAVI<34 mL/m2) after AF ablation have better long-term outcomes than those who do not. Furthermore, we investigated whether patients with a normal LA volume can also achieve normal LA function with AF ablation. METHODS: We enrolled 140 AF patients with baseline LAVI of ≥34 mL/m2, without AF recurrence for 1 year after the initial AF ablation. We acquired conventional and speckle-tracking echocardiographic parameters within 24 hour and at 1 year after the procedure. To define the normal range of LA function, age- and sex-matched controls without a history of AF were also enrolled. RESULTS: After restoration of sinus rhythm, LA structural and functional parameters significantly improved, and 75 patients (54%) had normal LA volume. During a median follow-up of 44 (31-61) months, 32 patients (23%) experienced a late recurrence of AF (AF recurrence >1 year). Patients who achieved normal LA volume after AF ablation had fewer late recurrences than those who did not (P < .01). However, LA abnormalities, especially LA dysfunction, persisted in AF patients even when the LA volume was normalized compared with controls. CONCLUSION: Patients who achieved normal LA volume had better long-term outcomes of AF ablation than those who did not; however, LA abnormalities persisted even after successful ablation of AF.