The Trajectory of the COVID-19 Vaccine Antibody Titers Over Time and the Association of Mycophenolate Mofetil in Solid Organ Transplant Recipients.

The COVID-19 vaccine will be safe and effective in solid organ transplant recipients (SOTs). However, the blunted antibody responses were also of concern. Few studies have reported prolonged serologic follow-up after 2 doses of BNT162b2 vaccine in SOTs. We performed a single-center, prospective observational study of 78 SOTs who received 2 doses of BNT162b2 vaccine. We identified the trajectory of antibody titers after vaccination among SOTs with or without mycophenolate mofetil (MMF) or withdrawn from MMF. We found low seroconversion rates (29/42: 69%) and low antibody titers in SOTs treated with MMF. An inverse linear relationship between neutralizing antibody titers and MMF concentration was confirmed in restricted cubic spline plots (P for effect < .01, P for nonlinearity = .08). For the trajectory of antibody responses, seroconversion and improved antibody titers were observed after withdrawal from MMF in SOTs who showed seronegative or low antibody titers at the first visit after 2 doses of vaccine (P for effect < .01, P for nonlinearity < .05, and P for interaction < .01). We identified increased B-cell counts after withdrawal from MMF (P < .01). The recovery of antibody responses was seen in SOTs withdrawn from MMF. The trajectories of antibody responses were modified by MMF administration.

Infective endocarditis caused by multidrug-resistant Streptococcus mitis in a combined immunocompromised patient: an autopsy case report.

An autopsy case of infective endocarditis caused by multidrug-resistant Streptococcus mitis was described in a patient with a combination of factors that compromised immune status, including autoimmune hemolytic anemia, post-splenectomy state, prolonged steroid treatment, and IgA deficiency. The isolated S. mitis strain from blood culture was broadly resistant to penicillin, cephalosporins, carbapenem, macrolides, and fluoroquinolone. Recurrent episodes of bacterial infections and therapeutic use of several antibiotics may underlie the development of multidrug resistance for S. mitis. Because clinically isolated S. mitis strains from chronically immunocompromised patients have become resistant to a wide spectrum of antibiotics, appropriate antibiotic regimens should be selected when treating invasive S. mitis infections in these compromised patients.

Potential role of high molecular weight hyaluronan in the anti-Candida activity of human oral epithelial cells.

Candida albicans is both a commensal and a pathogen in the oral mucosa. Previous studies have indicated that epithelial cell-associated carbohydrate moiety can inhibit C. albicans growth. In the present study, the mechanisms by which epithelial cells inhibit Candida growth were studied by examining the effect of hyaluronan (HA). A coculture of C. albicans and KB cells or COS-7 cells inhibited in vitro growth of the fungus by 50-87% at an effector-to-target (E:T) ratio of 80:1. Removing extracellular HA by hyaluronidase caused a significant decrease in the anti-Candida activity of the cells. In addition anti-Candida activity was observed at 1 micro g/ml HA (2000 kDa). The antifungal activity of extracellular HA was further studied by transiently transfecting COS-7 cells with human HSA1, HSA2, or HSA3 in order to produce high levels of extracellular HA. All of the transfectants inhibited C. albicans growth in vitro by 51-65% compared to 38% inhibition by the vector control (P<0.05). These results suggest that the anti-Candida activity of epithelial-cells is mediated by extracellular HA.