B Cell Response After Intradermal Inoculation of Multidrug Resistant Enterococcus Faecalis in Swiss Albino Mice

As resistance to last-resort antibiotics, Enterococcus faecalis is emerging as a significant health risk. To combat this, immune prophylaxis can provide effective alternatives. This research aims to assess the protective efficacy of antibodies generated by inactivated vaccinations against multidrug-resistant E. faecalis. This study include the intradermal inoculation of formalin-inactivated MDR E. faecalis, isolated from urine samples, into 15 Swiss albino mice. Two weeks following the third immunization dose, mice were challenged intraperitoneally with live E. faecalis and monitored for 14 days. Tail blood samples were collected on the 14th day after each inoculation, followed by cardiac puncture post-challenge. Mice spleens were cultured in RPMI media with fetal bovine serum for six days, and supernatants were collected. The antigen-binding capacity of serum antibodies and splenic lymphocyte culture supernatants generated by the vaccine was evaluated using ELISA. The study found that 100% of the vaccinated mice survived the challenge. Both pre- and post-challenge immunized serum immunoglobulin G antibodies and splenic lymphocyte culture supernatants exhibited significantly higher optical density values in ELISA compared to control mice. Immunization with formaldehyde-inactivated Enterococcus faecalis resulted in increased levels of IgG antibodies in both serum and splenic lymphocyte culture supernatants, leading to a 100% survival rate in immunized mice. Therefore, it can be concluded that immunization of Swiss albino mice with formaldehyde-inactivated MDR Enterococcus faecalis generates antibodies and induces a B cell response.