A case of hypervirulent K1-ST23 Klebsiella pneumoniae endocarditis and papillary muscle rupture secondary to multiple site abscesses.

Hypervirulent Klebsiella pneumoniae (hvKP) causes multisite infections and abscesses. However, endocarditis is a rare presentation of hvKP infection. Herein, we report a case of K. pneumoniae native valve infective endocarditis secondary to community-acquired liver and prostate abscesses. The patient developed papillary muscle rupture, leading to mitral regurgitation, and underwent emergent mitral valve replacement. The diagnosis of endocarditis was confirmed microbiologically and histologically. The causative strain belonged to the hypermucoid K1 capsular genotype and possessed the rmpA gene. The genome sequence was deposited in GenBank under the accession number JAQZBZ000000000.

Comparison of antibody response following the second dose of SARS-CoV-2 mRNA vaccine in elderly patients with late-stage chronic kidney disease.

Background: Currently, it is unclear whether the progression of chronic kidney disease (CKD) could be an independent predictor of antibody response after administration of a COVID-19 vaccine. This study aimed to investigate the immune response to COVID-19 vaccination in patients with CKD stage G4 to G5 without renal replacement therapy and G5D using the recommended dose and schedule. Methods: This retrospective single-center cohort study evaluated immunogenicity regarding antibody response after COVID-19 vaccination in our hospital for late-stage CKD patients aged ≥ 60 years. We evaluated antibody responses in 48 patients with CKD G4, 35 patients with CKD G5, and 70 patients undergoing hemodialysis (HD; CKD G5D). Results: After the second vaccination, anti-SARS-CoV-2-S (Spike) IgG levels were found to be positive (> 0.8 U/mL) in all CKD G4 and G5 patients (100%), and 69 of 70 HD patients (98.5%). The median (interquartile range [IQR] S-IgG level (Ab titers) was 358 [130.2-639.2], 218 [117-377], and 185.5 [95.1-323.5] U/mL in the CKD G4, G5, and HD groups, respectively. The median S-IgG levels were significantly lower in the HD group than in the CKD G4 group (p < 0.01). However, there was no significant difference in the antibody titers between the CKD G4 and G5 groups. To further analyze the decline in S-IgG levels after 6 months, we additionally assessed and compared antibody titers at 1 month and 6 months after the second vaccination in the HD group. Compared with the median S-IgG levels of 185.5 [95.1-323.5] U/mL 1 month after the second dose, the median S-IgG level 6 months thereafter was significantly decreased at 97.4 [62.5-205.5] U/mL (p < 0.05). Conclusions: We highlight two major factors of variability in the vaccine response. First, in elderly patients with late-stage CKD, antibody titers tended to be lower in the G5D group than in the G4 and G5 groups despite the shorter time since vaccination; therefore, CKD stage progression might cause a decline in antibody titers. Second, waning immune responses were observed 6 months after second dose administration in HD patients advocating a potential need for a third booster dose vaccine after 6 months.