The importance of glucose for the Escherichia coli mediated citrate depletion in synthetic and human urine

Objective: Escherichia coli has previously been shown to reduce urine citrate and influence urine pH. In this study the influence of glucose on the E. coli mediated citrate decrease has been investigated. Material and methods: In synthetic urine, a glucose concentration of greater than or equal to1 mmol/l was a prerequisite for bacteria to grow and lower citrate. At glucose concentrations greater than or equal to5 mmol/l an E. coli mediated pH decrease correlated to urine glucose was observed. Results: In human urine, variations in urine glucose influenced the citrate decrease and addition of glucose accelerated the E. coli mediated citrate decrease, which in certain urines could be very pronounced. Conclusions: Citrate has a pronounced effect on the activity product of calcium oxalate and calcium phosphate and the E. coli mediated decrease in urine citrate may be involved in the formation of urinary tract stones and catheter encrustations.