Since the introduction of PCNL in 1976, the safety and efficacy of this minimally invasive technique have significantly improved. As a result, PCNL has become the preferred treatment for complex and large stones. However, One of the most serious consequences is still post-PCNL infection.13 Research indicates that the occurrence of infectious complications following PCNL surgery varies between 2.8% and 32.1%.Urosepsis is a potentially serious complication, with the pathogenesis of which ranges from infection to systemic inflammatory response syndrome, followed by progression to sepsis. However, due to the unique pathogenesis of urosepsis, it is often difficult to detect this disease early in the clinic. Delays in the diagnosis and treatment of sepsis increase mortality, prolong hospitalization, and increase costs.14Nonetheless, the negative effects can be lessened through prompt identification and management of sepsis.15As a result, it is critical to identify risk factors for urosepsis early in order to avoid serious postoperative complications.
The occurrence of PCNL-US has been found to be associated with a variety of factors, including positive urine cultures, positive urinary nitrites, urinary leukocytes, blood leukocytes, staghorn stones, stone loading, duration of surgery, bleeding, diabetes mellitus, and sex. Regarding the risk factors mentioned above, there is no consensus on the concept of a positive urine culture. Preoperative urine cultures are routinely performed prior to PCNL to assess the risk of infection and sepsis. Teh, K. Y16 demonstrated that Patients exhibiting positive preoperative urine cultures demonstrated an almost fourfold increased likelihood of developing post-percutaneous nephrolithotomy (PCNL) sepsis compared to those with negative cultures, with incidence rates of 8.41% and 2.2%, respectively. However, several studies have found that a negative bladder urine culture does not necessarily indicate that there are no bacteria present in the stone or renal pelvis. This may be due to underlying urinary stone obstruction. 17Several studies have shown pelvic urinary infections in up to one-third of patients with negative bladder urine cultures, half of whom had positive stone cultures.18Eswara. et al.19reported that urosepsis occurred in 3% (11/328) of patients, 8 of whom had a positive stone culture (SC). However, none of the patients had a positive preoperative mid-stream urine culture. The authors suggested that preoperative midstream urine culture results did not directly correlate with pyelocentesis urine results or stone culture results. The reason for this discrepancy was that the uropathogens detected in mid-stream urine were not consistent with those found in the renal pelvis or in stones. Specifically, Staphylococcus aureus was predominant in stone cultures, while Escherichia coli was predominant in urine cultures.A total of 14 studies involving 3,540 patients were analyzed via meta-analysis. The findings of these studies concluded that renal pelvic urine cultures or stone cultures were more reliable in predicting postoperative systemic inflammatory response syndrome (SIRS) and urosepsis. Additionally, these cultures were found to be effective in identifying causative microorganisms and guiding antibiotic therapy in patients with PCNL, as compared to preoperative mid-stream urine cultures20.The guidelines from the American Urological Association (AUA) and the European Association of Urology (EAU) for patients with positive urine cultures do not provide recommendations for the duration of perioperative antibiotics. However, they strongly recommend collecting stone samples after lithotripsy to guide the selection of postoperative antibiotics.8, 21Recent studies have shown that patients with Positive urine cultures should be managed with suitable antibiotics for a minimum duration of seven days prior to surgical intervention.22, 23Similarly, the Chinese Urological Association (CUA) guidelines recommend a 1–2 week course of antibiotics for patients with positive urine cultures. A cross-sectional survey conducted by Zhang et al. examined the use of antibiotics for PCNL in China. The study found that urologists in China commonly used cephalosporins as the primary antibiotic prior to PCNL, followed by quinolones.24Many studies from various regions of China, however, have shown that the majority of uropathogens isolated from urine or stones of patients with urinary tract stones exhibit high resistance to cephalosporins (such as cefuroxime and ceftriaxone) and quinolones (such as ciprofloxacin and levofloxacin). Therefore, antibiotics should be selected rationally based on the local bacterial spectrum and drug sensitivity. Therefore, stone culture and renal pelvic urine culture should be routinely tested as much as possible in actual clinical practice. This will further enhance the ability to predict and prevent the occurrence of urosepsis.
Urinary nitrites are formed through bacterial reduction reactions of nitrates in the urine. Because urinary tract infections caused by gram-negative bacteria can be diagnosed quickly but indirectly by testing for urinary nitrites, a positive test for urinary nitrites indicates the presence of gram-negative bacteria in the urethra, especially Escherichia coli.25The more virulent the Gram-negative bacteria, the more likely they are to be present. The more virulent Gram-negative bacteria are more active at higher urate concentrations, which often indicates a more severe infection in the patient.26Gu et al. showed that patients with preoperative positive urinary nitrite had up to 3.33 times higher risk of urosepsis compared to patients with negative urinary nitrite.27Our study also suggests a higher risk of positive urinary nitrite levels. Urinary nitrite has a high specificity (98%) but low sensitivity (23%-43%) due to factors such as urination within 4 hours, low dietary nitrate intake, and urine dilution, which may result in false negatives.28For these reasons, several studies have combined levels with leukocyte and leukocyte esterase levels to increase the diagnostic precision of urinary tract infections.29The findings of these studies are summarized in the table below. Other researchers have found that the combination of urinary leukocytes and urinary nitrites has a sensitivity of 92% and a specificity of 98% when compared to the combination of urine and stone cultures. This combination is superior for early prediction of PCNL-US. The reason for this is that urine bacterial cultures are time-consuming and can also be affected by sample contamination. Because normal urine tests are less expensive and time-consuming, clinical urologists prefer to use them as a diagnostic tool in their daily practice.30 In a recent study, a urine nitrite-based model showed a greater net clinical benefit than a urine culture-based model for post-PCNL infections.31This is similar to the findings of our study.
Most studies have focused on the factors associated with postoperative fever after PCNL, and there are fewer reports on whether preoperative fever affects the occurrence of PCNL-US. We defined preoperative fever as a body temperature above 38°C. Preoperative fever also implies the presence of underlying urinary tract infections (UTI), most of which are caused by Escherichia coli.Bacterial adherence within the urinary tract plays a significant role in both colonization and invasion, as well as in the formation of biofilms and the damage to host cells.Biofilms can contribute to the persistence of urothelial and biomaterial surfaces by protecting bacteria from hydrodynamic scavenging, as well as host defense mechanisms and the killing activity of antibiotics. The persistence of biofilms leads to persistent UTIs and, consequently, stone formation.32Some studies have shown that preoperative UTI can lead to a decline in renal function one month after percutaneous nephrolithotomy in patients with single-kidney staghorn stones.33Additionally, a history of recurrent UTI is an independent risk factor for postoperative SIRS after PCNL.34Yang et al discovered a strong association between preoperative stone fever and unfavorable postoperative outcomes in patients with complex upper urinary tract kidney stones, emphasizing the importance of adequate preoperative treatment.35In addition, an analysis of a predictive model for infectious stones showed that preoperative fever was a significant predictor of infectious stone formation. Patients with preoperative fever were 2.37 times more likely than patients without fever to have infectious stones. Therefore, patients with preoperative fever should be identified and treated before surgery.
The SII is a multi-marker index that objectively reflects the balance between inflammation and immunity in patients with malignant tumors. It can be used as a prognostic indicator in cancer research.36Studies have reported that elevated SII levels are associated with a poorer prognosis and higher mortality in patients with cardiovascular disease.37 It has also been documented that SII is a marker for chronic obstructive pulmonary disease.38Although LMR, NLR, and PLR were not strongly correlated with urosepsis in this study, SII was strongly correlated. The exact mechanism needs to be further explored, but this is first to study the relationship between SII and urosepsis.
This study also has some limitations. First, single-center studies can bias the results and their value. Therefore, further validation is needed to determine whether systemic inflammatory markers have clinical value, particularly through multi-center studies with large sample sizes.