Comparison of Safety and Vector-Specific Immune Responses in Healthy and HIV-Infected Populations Vaccinated with MVA-B.

There are few studies comparing the safety and immunogenicity of the same HIV immunogen in healthy volunteers and HIV-infected individuals. We analyzed demographics, adverse events (AEs), and immunogenicity against vaccinia virus in preventive (RISVAC02, n = 24 low-risk HIV-negative volunteers) and therapeutic (RISVAC03, n = 20 successfully treated chronically HIV-1-infected individuals) vaccine phase-I clinical trials that were performed with the same design and the same immunogen (modified vaccinia virus Ankara-B: MVA-B). Total AEs were significantly higher in HIV-infected patients (mean AEs/patient 6.6 vs. 12.8 (p < 0.01)). Conversely, the number of AEs related to vaccination (AEsRV) was similar between both groups. No grade III or IV AEsRV were observed in either clinical trial. Regarding the immunogenicity, the proportion of anti-vaccinia virus antibody responders was similar in both studies. Conversely, the magnitude of response was significantly higher in HIV-infected patients (median binding antibodies at w8 267 vs. 1600 U/mL (p = 0.002) and at w18 666 vs. 3200 U/mL (p = 0.003)). There was also a trend towards higher anti-vaccinia virus neutralizing activity in HIV-infected individuals (proportion of responders 37% vs. 63% (p = 0.09); median IC50 32 vs. 64 (p = 0.054)). This study confirms the safety of MVA-B independent of HIV serostatus. HIV-infected patients showed higher immune responses against vaccinia virus.

Pulsed electric fields reduce bacterial attachment to stainless steel plates.

The purpose of this study was to evaluate the capacity of pulsed bilateral electric fields to control bacterial attachment on stainless steel plates. Previously sterilized circular metal plates of stainless steel were submerged in a liquid medium with a known concentration of Staphylococcus epidermidis and incubated for 1 hour at 36oC while a 200 Hz pulsed electric field of 18 V/cm was applied for 2.5 µseg and then sonicated for 5 minutes in 10 ml of saline. Three different models were cultured and compared: 1) negatively-charged plate, 2) positively-charged plate, and 3) control plate without electric current. A total of 39 metal plates were processed. The median adherence in the control group and the electric field group was 312 CFU/mm2 and 16,2 CFU/mm2 respectively (p < 0.001, reduction of 95% of bacterial attachment). Bilateral pulsed electric field is able to reduce bacterial attachment on stainless steel plates in in vitro conditions.

Adherence of S. epidermidis on different metals. A comparative in vitro study.

AIM: Staphylococcus epidermidis is the most common cause of orthopedic infections. Adhesion and biofilm formation on orthopedic implant surfaces play an important role in the physiopathology of these infections. The aim of our study was to evaluate the adhesion of S. epidermidis on the surface of metals usually used in orthopedics. METHODS: Previously sterilized circular metal plates of titanium (Ti), porous titanium (p-Ti), cobalt chromium (CoCr) and stainless steel (SS) were hung completely submerged in a liquid medium with a known concentration of S. epidermidis (RP62A). They were incubated for 1 h or 24 h at 36°C. After incubation, each plate was washed with PBS and sonicated during 5 minutes in 10 mL of saline. Different dilutions were performed and 100 µL from each sample was cultured on agar plates. RESULTS: 26 metal plates were incubated for 1 h and other 55 metal plates for 24 h. The lowest bacterial count (cfu/mm2) at 1 h was observed in CoCr plates while in p-Ti it was 6 times higher. At 24 h the highest bacterial count was observed in SS plates while the lowest in Ti. However, these differences were not statistically significant. CONCLUSIONS: After 1 h and 24 h of exposure, the lowest adherence was observed in CoCr and Ti plates, respectively. However, bacterial attachment occurred with all materials. It is necessary to further investigate new materials able to avoid bacterial attachment.

Use of cemented spacer with a handmade stem to treat acute periprosthetic tibial fracture infection: a case report.

We report an 85-year-old woman with dementia and dependent for normal life activities who was admitted due to a left periprosthetic tibial fracture. The tibial component was replaced by one with a long stem and she was discharged. Four weeks after the intervention the patient was re-admitted due to an acute prosthetic joint infection. All the components were removed and a bone-cement spacer with a handmade stem with a metal core was implanted. Radiological signs of fracture consolidation were observed after 3 months of follow-up. Due to the previous health status of the patient, it was decided to keep the spacer as a definitive treatment. After 24 months, the patient was able to sit without pain and to stand up with help using a knee brace. There were no radiological or clinical signs of infection.