Urinary tract infection (UTI) is a multiple disease that ranks second only to respiratory infections in infectious diseases and is one of the most common infectious diseases among adults. After the first urinary tract infection, the probability of recurrence within half a year and within one year was as high as 24% and 70%, respectively. Urinary tract infection itself has the characteristics of easy recurrence, which is closely related to the abuse of antibiotics, the generation of bacterial resistance, and the decline of local immune function of mucosa.~In the urinary tract, the antibacterial peptide Cathelicidin is mainly located in the proximal tubules of the kidney and the epithelial cells of the renal pelvis and ureter. LL37 is the only antibacterial peptide present in the human body of the Cathelicidin family, which can be regarded as a natural antibiotic produced by the body. Antibacterial peptides have a broad-spectrum antibacterial effect and can exert antibacterial effects against both Gram-positive and Gram-negative bacteria. Vitamin D intake increases the activity of endogenous antimicrobial peptides. Preclinical cell test of Zensun Sci. & Tech. Co., Ltd. confirmed the induction of LL37 in urethral epithelial cells by vitamin D and its broad-spectrum antibacterial effect. Animal experiments also showed the therapeutic effect of LL37 on UTI.
The aim of this study was to initially evaluate the optimal dose, efficacy, and safety of vitamin D3 for reducing recurrence of recurrent urinary tract infections (rUTIs).