Hidden danger in kidney stones: Risk of kidney damage may triple

The international study involving the research team of Prof. M. Pilar Laguna and Prof. Jean De La Rosette, faculty members of the International School of Medicine at Istanbul Medipol University, focused on infectious complications observed after percutaneous nephrolithotomy (PCNL), a commonly performed procedure for the treatment of kidney stones. The researchers demonstrated that stone cultures obtained during surgery provide valuable information for identifying infected stones and predicting postoperative complications.

The study, entitled“Unravelling the Added Value of Urinary Stone Cultures Towards Infectious Complications Following Treatment of Renal Stones”was published in the international peer-reviewed scientific journal Antibiotics.

AN OFTEN OVERLOOKED RISK IN KIDNEY STONE TREATMENT
Kidney stone disease affects millions of people worldwide, and some stones may harbor bacteria and are therefore classified as “infected stones.” These stones not only cause pain and urinary tract problems but can also increase the risk of postoperative complications, including fever, severe infections, sepsis, and kidney damage.

To investigate the role of infected stones in the development of postoperative infections in greater detail, the research team conducted a prospective study involving 126 patients. The study evaluated preoperative urine samples, blood parameters, kidney function, and stone characteristics, while stone samples collected during surgery were sent for culture analysis.

INFECTED STONES INCREASE THE RISK OF SERIOUS COMPLICATIONS
According to the study findings, stone cultures were positive in 12.6 percent of patients. Postoperative infectious complications were found to occur significantly more frequently among patients with positive stone cultures.

Notably, all patients whose stones were found to contain bacteria developed postoperative fever, while 93.8 percent experienced Systemic Inflammatory Response Syndrome (SIRS), a condition resulting from the body's excessive response to infection. In contrast, the rates of fever and SIRS among patients with negative stone cultures remained at only 13.6 percent. The researchers emphasized that infected stones represent a strong predictor of postoperative infectious complications.

RISK OF KIDNEY DAMAGE IS THREE TIMES HIGHER
The study also found that infected stones pose significant risks not only for infection but also for kidney function.

Patients with infected stones were found to have an approximately threefold higher risk of developing acute kidney injury following surgery compared with other patients. In addition, these patients experienced longer hospital stays and higher complication rates. The researchers noted that infected stones may be associated with processes that can ultimately lead to long-term loss of kidney function.

E. COLI IDENTIFIED AS THE MOST COMMON BACTERIUM
The study revealed that the most frequently detected microorganism in both stone samples and preoperative urine samples was Escherichia coli (E. coli), one of the most common causes of urinary tract infections.

More than half of the patients with positive stone cultures also had positive preoperative urine cultures. Furthermore, the detection of the same bacterial species in both stone and urine cultures suggested that routine urine cultures may serve as an important indicator for predicting infected stones. The researchers stated that this finding supports the clinical value of urine cultures, contrary to the conclusions of some previous studies.

LARGER STONES ARE MORE LIKELY TO BE INFECTED
The study showed that infected stones differ not only in their bacterial content but also in their structural characteristics.

Patients with positive stone cultures were found to have larger stone volumes. The researchers suggested that bacterial biofilms and infectious foci within the stones may contribute to accelerated stone growth. In addition, infected stones may exhibit a low-density central core on computed tomography scans, which could serve as an important radiological indicator of infection.

ANTIBIOTIC RESISTANCE RAISES CONCERNS
One of the most striking findings of the study concerned antibiotic resistance.

The researchers observed that some patients continued to develop infections despite receiving prophylactic antibiotics before surgery. Culture analyses demonstrated that the bacteria responsible for these infections could exhibit high levels of resistance, particularly to third-generation cephalosporins and fluoroquinolone antibiotics.

The researchers emphasized that this increase in antibiotic resistance highlights the need to limit indiscriminate antibiotic use and to expand targeted treatment approaches based on culture results. The study also found that many bacterial strains remained susceptible to carbapenems, a class of potent antibiotics commonly used to treat resistant infections.

HIGH-RISK PATIENTS CAN BE IDENTIFIED BEFORE SURGERY
According to the study findings, factors such as sex, chronic kidney disease, positive preoperative urine cultures, elevated creatinine levels, and large stone volume were associated with infected stones.

In particular, patients with chronic kidney disease were found to have a significantly greater likelihood of positive stone cultures. The researchers stated that these findings may help identify high-risk patients before surgery and play an important role in preventing complications through closer monitoring and more individualized management.

CONTRIBUTING TO A SAFER APPROACH IN KIDNEY STONE TREATMENT
The study demonstrated that infected kidney stones are not only a source of existing infection but also a significant predictor of serious postoperative infectious complications.

The findings suggest that the combined evaluation of preoperative urine samples and kidney stone cultures may help identify high-risk patients in advance. The study also underscores the importance of appropriate antibiotic selection and culture-guided treatment strategies in an era of increasing antibiotic resistance.

The researchers conclude that early detection of infected stones and the implementation of appropriate treatment strategies may reduce the risks of both infection and kidney damage. The findings are expected to contribute to the earlier identification of high-risk patients, more accurate treatment planning, and the reduction of serious postoperative complications. In this respect, the study provides an important scientific foundation for the development of safer and more personalized treatment approaches in kidney stone surgery.