Key Points Question What are the humoral immune response rates and risk factors associated with diminished response after COVID-19 vaccination in recipients of solid organ transplant? Findings In this systematic review and meta-analysis of 29 studies and 11 713 recipients of solid organ transplant, seroconversion rates increased with progressively increased numbers of mRNA COVID-19 vaccine doses. Older age, recent transplantation, deceased donor status, active use of antimetabolites, and recent exposure to antithymocyte globulin or rituximab were risk factors associated with diminished humoral immune response after receiving 2 doses of mRNA vaccines. Meaning These findings suggest that more efforts are needed to modulate the risk factors associated with reduced humoral responses among recipients of solid organ transplant.

Human vascular pythiosis is a life-threatening condition caused by Pythium insidiosum. Patients with unresectable intra-abdominal artery involvement have not previously survived, despite being treated with antifungal agents and immunotherapy. We report two novel cases of intra-abdominal pythiosis in patients for whom surgery could not be performed, who were successfully treated with adjunctive antibacterial agents.

Ocular pythiosis is the second most common form of human pythiosis, and the rates of evisceration/enucleation in Thailand are 55–79%. This prospective study was conducted to evaluate treatment outcomes of the combination therapy protocol and the potential use of serum (1→3)-β-glucan (BG) and Pythium insidiosum-specific antibody (Pi-Ab) as an aid to diagnosis and monitoring of ocular pythiosis. Thirty patients were enrolled in the study and 14 (non-globe salvage) required evisceration/enucleation. The globe salvage group was significantly younger, and first ocular surgeries were performed significantly sooner than in the non-globe salvage group. Serum BG and Pi-Ab levels were similar among the 2 groups over time. In vitro susceptibility testing of antifungal agents revealed relatively high minimum inhibitory concentrations and lack of synergistic effect. Serum BG and Pi-Ab would not be useful in diagnosis and monitoring of ocular pythiosis. Until effective antimicrobial agents are discovered, ocular surgeries are still the mainstay therapy in Thailand.

Vascular pythiosis is a rare, neglected, life-threatening disease with mortality of 100% in patients with incomplete surgical resection or patients with persistently elevated serum β-d-glucan (BDG). The study was conducted to understand the clinical outcomes of new treatment protocols and potential use of erythrocyte sedimentation rate (ESR) and c-reactive protein (CRP) as alternative monitoring tools, given recent favorable minimum inhibitory concentrations (MICs) of antibacterial agents and prohibitive cost of serum BDG in Thailand. A prospective cohort study of patients with vascular pythiosis was conducted between February 2019 and August 2020. After diagnosis, patients were followed at 0.5, 1, 1.5, 3, and 6 months. Descriptive statistics, Spearman’s correlation coefficient, and general linear model for longitudinal data were used. Amongst the cohort of ten vascular pythiosis patients, four had residual disease after surgery. Among four with residual disease, one developed disseminated disease and died, one developed relapse disease requiring surgery, and two were successfully managed with antimicrobial agents. The spearman’s correlation coefficients between BDG and ESR, and between BDG and CRP in patients without relapse or disseminated disease were 0.65 and 0.60, respectively. Tetracyclines and macrolides had most favorable minimum inhibitory concentrations and synergistic effects were observed in combinations of these two antibiotic classes. Adjunctive use of azithromycin and doxycycline preliminarily improved survival in vascular pythiosis patients with residual disease. Further studies are needed to understand the trends of ESR and CRP in this population.

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