Comparative immunogenicity and protective efficacy of formaldehyde-inactivated whole-cell and sonicated whole-cell extract vaccines against multidrug-resistant Pseudomonas aeruginosa in mice

Pseudomonas aeruginosa is a significant cause of healthcare-associated infections, with growing antimicrobial resistance limiting treatment options. This study examined the immunogenicity and protective benefits of two distinct vaccines targeting multidrug-resistant (MDR) P. aeruginosa in mice.

The research utilized clinical isolates of P. aeruginosa collected between July 2022 and February 2026 from Dhaka Medical College Hospital. Formaldehyde-inactivated whole-cell vaccine and a sonicated whole cell extract formulation were created from the pathogen. A total of 144 female Swiss albino mice, aged 6-8 weeks, were employed: 120 mice participated in two separate immunization trials, while 24 were utilized for determining the lethal dose (LD50).

Each mouse received three intramuscular injections on days 0, 14, and 28. The development of antigen-specific serum IgG was measured using enzyme-linked immunosorbent assay (ELISA), while functional antibody activity was gauged through serum bactericidal assay (SBA). The effectiveness of the vaccines in preventing lethal intraperitoneal challenges was assessed.

For vaccine preparation, ten MDR P. aeruginosa isolates were chosen randomly from the clinical samples. The sonicated preparation had a protein concentration of 1.872 mg/mL. Both vaccination groups exhibited notably higher anti-P. aeruginosa IgG responses compared to the control group after immunization (p value less than 0.05).