Preliminary Study On The Mechanism Of Ur Inary Stones Caused By Bacteroides

Background and objectiveUrolithiasis,also known as urolithiasis,is one of the oldest diseases known to medicine.It is estimated that 1-15%of individuals will have urolithiasis in their lifetime,and the prevalence and incidence of urolithiasis is increasing worldwide.The prevalence of kidney stones in Chinese adults was 5.8%(6.5%in men and 5.1%in women).Without proper treatment,urolithiasis can lead to blockage of the ureter,hydronephrosis,hematuria,frequent urinary tract infections,vomiting or painful urination,which can eventually lead to permanent damage to the kidneys.However,the mechanisms of stone formation and development remain largely unclear.Stones are diverse in mineralogy,but regardless of type,their formation is a complex and multistep process involving urine supersaturation,nucleation,growth,and aggregation.Urinary stone formation is related to a variety of factors,including climate,age,metabolic syndrome,dietary habits,and bacterial infection.A variety of promoting and inhibitory factors play key roles in stone formation.However,the mechanism of stone formation and growth is far from being elucidated.Although the association between urolithiasis and urinary tract bacterial infection is widely accepted,its mechanism of action,causative microorganisms,and its antimicrobial-drug susceptibility pattern remain understudied.The chemical properties of urine play a key role in the formation of infectious stones and are determined by saturation,pH,and the presence of crystallization and aggregation regulators in the urine,as well as biofilm formation,but the mechanism of urinary infection stone formation is far from complete.Not clarified.A common complication in patients undergoing ureteral stent placement after invasive surgery is mural stone formation on the stent wall.The wall-column stones formed after the stent remains in the patient’s body for a long time will not only greatly affect the drainage function of the stent,cause hydronephrosis,but also cause mucosal damage,bleeding,stenosis,etc.At present,the research on the formation mechanism of stent-column stones is also very limited,and effective measures cannot be used to prevent the formation of stent-column stones and their complications.Previous studies have shown that indwelling catheters are an important risk factor for the occurrence of infectious stones,and the incidence of urinary tract infections in patients with positive ureteral stents attached to the wall is relatively significant.Changes are closely related to the formation of urinary tract infection stones.The purpose of this study was to use bacterial gene sequencing technology to compare the difference indicators of urinary flora in patients with stent-coated stones and patients without wall-mounted stones.Find the target dominant bacterial genus,and try to establish an animal model of bacteria-foreign body-stones.Through the comparative testing of clinical samples,animal model repetition and electron microscope verification,based on the existing cognition of infection factors leading to stone disease,a more rigorous and detailed theoretical hypothesis is put forward,and it is believed that the abnormal changes in the diversity of urinary flora And specific local dominant bacteria are one of the reasons for the occurrence and development of ureteral stent wall calculi and even urinary tract infection calculi.Research purposes1.To investigate the distribution characteristics of urinary flora in patients with ureteral stent-coated calculi2.To explore the relationship between specific bacteria and the formation of ureteral stent wall stones.3.To establish a new animal model of bacteria-related stones.Methods[1]Using the 16srDNA bacterial gene sequencing technology,the bacterial populations(bacterial abundance,species and proportion,etc.)of the urine and stone(surface)samples of patients with and without wall stones in stents were analyzed.The differences in bacterial diversity indicators between the two groups were used to clarify whether the specific dominant flora was related to the formation of ureteral stent wall stones.[2]Try to establish a new animal model of bacteria-related stones to verify the relationship between the target bacteria and the occurrence of stent-coated stones.[3]After the successful establishment of the animal model of calculi,the calculi samples in the bladder and foreign bodies in the bladder were examined by scanning electron microscopy and analyzed by Fourier transform infrared spectroscopy.Whether the survival of bacteria in the bladder can be observed and whether there is biofilm production,and the composition of stones can be detected to determine whether the formation of stones is related to the target bacteria,and the data can be statistically analyzed and verified.ResultsThere was a great difference in the urinary bacterial diversity index between the patients with wall stones and the patients without wall stones.There were many kinds of bacteria in the urine of patients with stones,and the top three genera were Lactobacillus(23.1%),Bacteroidetes(18.8%)and unclassified Bacteroides(17.1%).The diversity of urinary bacterial flora in the acalculous group was significantly lower than that in the calculus group,and the main bacterial genera were Escherichia-Shigella(32.2%),Enterococcus(24.9%)and Pseudomonas(18.2%).The abundance of Bacteroides in the stone group was significantly higher,so we chose Bacteroides fragilis for animal experiments,and Bacteroides fragilis is a representative species of this genus.A rat bladder foreign body-calculus model was successfully established.Scanning electron microscopy confirmed that Bacteroides fragilis caused the formation of calculi attached to the spiral tube in the bladder of the rat.Statistical analysis supported the conclusion.The main component of the calculi attached to the spiral tube was calcium hydrogen phosphate stones,Carbonated Apatite and Magnesium Phosphate.ConclusionCompared with patients without stones,the types and numbers of bacteria in the urine of patients with ureteral stents wall stones were significantly increased,and the anaerobic bacteria and facultative anaerobic bacteria were significantly increased,and Bacteroides was the dominant bacteria kind.Bacteroidetes can play a role as an indispensable microorganism in the human metabolic system,but may also cause metabolic-related diseases represented by urinary tract infection stones.The successful establishment of the rat model can be verified.This suggests that for patients with indwelling ureteral stents,Antibacterial therapy against susceptible species may be helpful in preventing the formation of calculi attached to stents.For patients with urinary calculi,the target regulation of urinary bacteria deserves further research and clinical application.