Journal Article

 

The main question this article was attempting to answer was how exactly do bacteria relate to kidney stones. It aimed to determine whether or not the connection between stones & UTIs was simply a coincidence or if there is an established causative relationship. Kidney stones are a common problem and contribute a significant amount to healthcare costs both inpatient as well as outpatient. Supersaturation of urine ultimately causes the stone formation. Research has been conducted that proves the connection between bacteria and struvite stones, however, more information is needed regarding the other types of kidney stones (i.e. calcium oxalate & calcium phosphate). Calcium oxalate is found in over 60% of stones and calcium phosphate is found in over 40% thereby making this an important topic to further develop.

The article features a study conducted in Taiwan indicating that UTI is the most common associated condition in those with stones and a retrospective review conducted in Sweden that also clearly displays the connection as well. The authors developed “EQUC” (enhanced quantitative urine culture) featuring more urine and longer incubation period to better analyze the presence of bacteria in urine. In 2015, using a study of 5 kidney stones & upper tract urine along with bladder urine, they found mostly E. coli in both the stone and urine samples themselves.

The mechanism by which bacteria may contribute to development of stones can be explained by two theories. Either bacteria adhere to crystals or bacteria produce citrate lyase which decreases urine citrate levels thus leading to crystal formation and supersaturated urine. Despite knowing that there is some sort of clinical connection, further research is required to determine if stones and bacteria are mechanistically associated with one another. Future studies should include sequencing a larger number of stones as well as creating model systems to test mechanistic overlap between bacteria and stones.