Therapeutic effects of silver nanoparticle and L-carnitine on aerobic vaginitis in mice: an experimental study

Aerobic vaginitis (AV) is a type of vaginal infection that occurs at the reproductive age of women. In this study, we aimed to study the possible anti-AV therapeutic effects of silver nanoparticles (AgNPs) and L-carnitine (LC) in the mouse model.

AV model was established by intra-vaginal inoculation of 108 CFU/mL Staphylococcus aureus and Escherichia coli (1:1) in adult NMRI mice. Susceptibilities of the bacteria were examined against AgNPs by inhibitory concentration (IC-50 and IC-90) and minimum biofilm inhibitory concentration (MBIC- 90) methods. The regimens therapy was intra-vaginal inoculation of AgNPs at MBIC- 90 and a daily injection of 250 mg/kg LC for two weeks. Mice were classified into healthy (control) and AV groups and then treated by LC, AgNPs, and AgNPs + LC. The vaginal smears were taken daily and tissue sections were prepared using the hematoxylin and eosin (H & E) method.

Minimum inhibitory concentrations (MICs) of AgNPs for E. coli, S. aureus, and their mixture were 250, 125, and 500 ppm, and their MBIC-90% were 500, 250, and 1000 ppm, respectively. The estrus cycle of mice treated with co-administration of AgNPs and LC was similar to the control group (P < 0.05). The results of histology also showed that infected mice were treated with AgNPs and LC, simultaneously.

Single bacteria are more sensitive than their mixed model to these NPs. Co-administration of AgNPs as an antibacterial agent and LC as an antioxidant agent can treat AV in the infected mice.