Probiotic Properties Evaluation Of Four Lactobacillus Strains And Their Therapeutic Effects On Vaginitis

Vaginal microecosystem is a part of human microecosystem,which is closely related to the development and health of female reproductive system.Vaginitis is a common disease and frequently-occurring disease in women.This kind of disease is mainly due to the destruction of the vaginal microecosystem and excessive proliferation of pathogenic microorganisms,thus causing the occurrence of vaginal inflammation.Candida albicans is an opportunistic pathogen that causes vulvovaginal candida vaginitis,which is the most common vaginal inflammation after bacterial vaginitis.At present,the treatment of vaginal infectious diseases is still based on antibiotic treatment,although this method can quickly treat the disease,but there are the disadvantages of repeated attacks of the disease,at the same time,this kind of drugs cannot repair the vaginal microecology has been destroyed.Lactic acid bacteria are an important factor to maintain the microecological balance of the vagina,and can maintain the stability of the vaginal environment through the mechanism of acid production,hydrogen peroxide production and adhesion competition.As a female probiotic,lactic acid bacteria have been used to prevent vaginal inflammation and regulate vaginal microecosystems,however,currently there are limited female probiotic products available in China,so this project is committed to screening and identifying lactic acid bacteria with good female probiotic characteristics,and using mouse model to evaluate its therapeutic effect on Candida albicans vaginitis.In this study,four strains of lactobacillus isolated from fermented food and vaginal secretions of healthy women were selected.Lactobacillus plantarum 021,Lactobacillus Crispatus-1,Lactobacillus Crispatus-2 and Lactobacillus crispatus-8.First,growth capacity,acid tolerance,bile salt tolerance,acid production and other activities were tested.Then,antibiotic sensitivity,bacteriostasis against pathogenic bacteria,and adhesion to epithelial cells were tested.Finally,a mouse vaginitis model was used to evaluate the therapeutic effect of Lactobacillus on candida albicans vaginitis.The results of in vitro experiment showed that the four strains of lactobacillus had strong growth ability,and the OD600 value of bacterial solution was more than 1.0 after 12 h culture.Compared with the control positive strain,it had better acid-producing ability.After 12 h growth,the pH value of the medium decreased from 6.5 to 4.3-4.8,that is,to reach the vaginal pH value of healthy women of childbearing age.The four lactobacillus strains could survive in medium that mimics gastrointestinal environment,that is,low acid(pH2-pH4)environment and high bile salt concentration(0.1-0.5%)can survive in the medium.Compared with the control strain,it was sensitive to most antibiotics and had stronger antibacterial activity against common pathogenic bacteria such as Candida albicans and golden grape bulb.The adhesion index between lactobacillus and cervical epithelial cells was62±6.6 cells/cell.The results of animal experiment showed that the vaginal inflammation of mice with candida albicans vaginitis was relieved by lactobacillus and clotrimazole.After treatment,the amount of candida albicans in vaginal lavage fluid of mice was lower than that of untreated group.The infection of Candida albicans in vaginal microecology was detected by Gram staining,which showed that the amount of candida albicans in the vagina gradually decreased and disappeared after treatment.After treatment,the redness of vaginal tissue disappeared and uterine wall atrophy relieved.After treatment,the infiltration of inflammatory cells was reduced and the shedding of vaginal mucosa was relieved.The expression of inflammatory cytokine IL-8 in vaginal lavage fluid was also significantly reduced after treatment.These results indicate that Lactobacillus plantarum 021 and three strains of Lactobacillus Crispatus have the characteristics of female probiotics,with strong antibacterial and adhesion ability.Meanwhile,in vivo experiments also show that they can improve the vaginal microecological environment and have a certain therapeutic effect on vaginitis.This study identified the probiotic activity of four lactobacillus strains and proved their therapeutic effect on vaginitis caused by Candida albicans through animal experiments,laying a foundation for further development of new female probiotic products.