PROSPECTS OF USING “HOSPITAL” VACCINES TO INCREASE THE EFFICIENCY OF COMBATING SYNOGNIOUS INFECTION (EXPERIMENTAL STUDIES)

Abstract

SUMMARY. In the context of rapidly increasing antibiotic resistance among bacterial pathogens, one of the most promising approaches to treating infected and wounded patients with infectious complications is the personalization of vaccine therapy through the use of autovaccine production technologies. An equally important aspect in the fight against Pseudomonas infections is the prevention of patient contamination with nosocomial strains and the prophylaxis of infection foci formation. To determine the feasibility of using multistrain vaccines produced from hospital-derived Pseudomonas aeruginosa strains, inactivated by photodynamic methods, in order to enhance the effectiveness of combating Pseudomonas infections.

Materials and methods. Using a photodynamic inactivation technique developed by our team, samples of multistrain vaccines were produced from five nosocomial P. aeruginosa strains. The production algorithm was analogous to that used in autovaccine manufacturing, as described in our previous publications.The difference lay in the use of five nosocomial P. aeruginosa strains – isolated from two patients, one high-risk individual (a healthcare worker), and two environmental sources within the intensive care unit of a military hospital – instead of a single bacterial culture. The resulting bacterial suspensions were mixed in equal proportions. The protective activity of the vaccines was assessed using 360 white outbred mice challenged with homologous (original) and heterologous P. aeruginosa strains. Therapeutic efficacy was evaluated based on survival rates in experimental and control groups. To assess the protective efficacy of the hospital-derived vaccine made from five freshly isolated nosocomial strains, mice were intraperitoneally vaccinated with 0.5 mL doses twice, at 6–7-day intervals. Fourteen days after the final administration, the animals were infected with the corresponding P. aeruginosa strain at a dose of 3LD₅₀.

Research results. Experimental findings demonstrated statistically significant protective activity of the multistrain hospital-derived vaccine against both homologous and heterologous P. aeruginosa strains (p<0.05). Survival rates among vaccinated animals were 2–3 times higher than those in the unvaccinated control group.Therapeutic administration of the vaccine to clinically ill mice resulted in a significant increase in survival–85.7 % compared to 30 % in untreated animals. Moreover, even when using a hospital-derived vaccine manufactured from heterologous Pseudomonas strains, the effectiveness of vaccine therapy remained high (survival rate – 66.7 %).

Conclusions. The results indicate that the use of photodynamically inactivated multistrain vaccines is a promising strategy for the prevention of nosocomial infections. This approach may contribute to reducing the emergence of multidrug-resistant hospital strains and the incidence of infectious complications in cases of wounds, burns, and trauma, as well as in patients with comorbid conditions. Additionally, it offers preventive potential against ventilator-associated pneumonia. Under certain conditions, such “hospital” vaccines may be employed not only for prophylaxis but also as an effective treatment modality for complications arising from combat-related injuries, antibiotic-resistant infections, and the risk of chronic infection development–thus representing a novel perspective in managing Pseudomonas infections in both wartime and peacetime settings.