Stone culture retrieved during percutaneous nephrolithotomy: is it clinically relevant?

Prediction of systemic inflammatory response syndrome and urosepsis after percutaneous nephrolithotomy by urine culture, stone culture, and renal pelvis urine culture: Systematic review and meta-analysis

Background

Percutaneous nephrolithotomy (PCNL) is thought to have an increased risk of infectious complications. This study evaluates the predictability of preoperative midstream urine culture (PMUC), stone culture (SC), and renal pelvis urine culture (RPUC) for post-PCNL systemic inflammatory response syndrome (SIRS) or urosepsis.

Method

After literature search in electronic databases (Embase, PubMed, Ovid, Science Direct, and Springer), studies were selected by following precise eligibility criteria. The quality of included studies was assessed, and meta-analyses of proportions were performed to seek culture positivity rates and incidence rates of post-PCNL SIRS/urosepsis. Meta-analyses of odds ratios (OR) were performed to evaluate the odds of positivity between SC and PMUC or RPUC, and the odds of post-PCNL SIRS/urosepsis with SC versus PMUC or RPUC.

Results

Nineteen studies (4829 patients) were included. Positivity rates of PMUC, SC, and RPUC were 16 % [95 % CI: 12, 20], 21 % [95 % CI: 16, 26] and 10 % [95 % CI: 7, 14] respectively. The odds of positivity were significantly higher for SC compared to PMUC (OR 1.37 [95%CI: 1.02, 1.84]; p = 0.037) or RPUC (OR 1.65 [95%CI: 1.25, 2.18] p < 0.0001). The incidence of post-PCNL SIRS and urosepsis was 21 % [95%CI: 17, 25] and 6 % [95%CI: 3, 10] respectively. The odds of post-PCNL SIRS were significantly higher with SC compared to PMUC (OR 2.45 [95%CI: 1.12, 5.38] p = 0.025) or RPUC (OR 2.10 [95%CI: 1.33, 3.30]; p = 0.001) positivity. The odds of developing urosepsis after PCNL were not significantly different between SC and PMUC positivity (OR 1.874 [95 % CI: 0.943, 3.723]; p = 0.073).

Conclusion

The risk of post-PCNL SIRS is found higher with SC than with PMUC or RPUC positivity. However, the risk of urosepsis may not be different between SC and PMUC.

Timing of midstream urine culture before endourological procedure-can we do better?-A comparative study

Endourological procedures are the mainstay of treatment for stone disease in the upper urinary system. Infection is a common complication, and urine cultures (UC) are often obtained preoperatively. In this study, we sought to investigate the role of positive UC in the 90 days prior to surgery (90PreOp) in predicting postoperative infectious complications in comparison to a single positive preoperative UC (PreOP). We compared the correlation between positive PreOp UCs and positive 90PreOp UCs with postoperative urosepsis, and a positive UC obtain proximal to obstruction (Prox UC) during percutaneous nephrolithotomy, ureteroscopy and a placement of nephrostomy tube or ureteral stent. Data from 140 consecutive patients were collected. PreOp UCs were positive in 15 (11%) of patients versus 31 of 140 (22%) positive 90PreOp UCs. All six sepsis events had a positive 90PreOp UC, and five had a positive PreOp UC. Fourteen (93.3%) out of 15 positive Prox UC had a positive 90PreOp UC, whereas only 7 (38.9%) had a positive 90PreOp UC. Positive 90PreOp UC outperformed PreOp UC in predicting positive Prox UC, OR = 12.8 (95% CI 3.70-44.30, p < 0.001), versus OR of 88.9 (95% CI 11.0-720.7, p < 0.001); sensitivity 93%(95% CI 68-100%) versus 47%(95% CI 21-73%); as well as area under the ROC curve(AUC), 0.90 (CI 0.80-0.95) for 90PreOp versus 0.70 (CI 0.56-0.82) for positive Prox UC. Uropathogen persistence was better identified when using 90PreOp UC (27%) than using PreOp UC (12%). We suggest reviewing UCs taken within 90 days preoperatively as this was found superior to a single preoperative midstream UCs in predicting postoperative infectious sequela after stone procedure.

A nomogram for predicting postoperative urosepsis following retrograde intrarenal surgery in upper urinary calculi patients with negative preoperative urine culture

Retrograde intrarenal surgery (RIRS) is one of the main surgical methods for upper urinary calculi, but severe complications of infection may occur after surgery. This study aimed to establish and validate a preoperative nomogram for predicting postoperative urosepsis following retrograde intrarenal surgery to treat upper urinary calculus in patients with a negative preoperative urine culture. We retrospectively recruited 1767 patients with negative preoperative urine cultures who underwent retrograde intrarenal surgery to treat upper urinary calculi from January 2017 to April 2022. The independent risk factors for urosepsis include a solitary kidney, positive urine nitrite, operative time ≥ 75 min, history of recurrent urinary tract infections, and history of diabetes were identified by univariate analysis and multivariate binary logistic regression analysis, which construct a nomogram. The receiver operating characteristic curve of the nomogram for predicting urosepsis was 0.887 in the training cohort and 0.864 in the validation cohort, respectively. The calibration curve and decision curve analysis demonstrated great consistency and clinical utility of the nomogram. Therefore, the nomogram combining preoperative independent risk factors can predict the probability of a postoperative urosepsis following retrograde intrarenal surgery in patients with a negative preoperative urine culture, which could help urologists take preventive measures in advance after surgery to avoid more serious complications of infection.

Heterogeneity in stone culture protocols and endourologist practice patterns: a multi-institutional survey

Kidney stone cultures can be beneficial in identifying bacteria not detected in urine, yet how stone cultures are performed among endourologists, under what conditions, and by what laboratory methods remain largely unknown. Stone cultures are not addressed by current clinical guidelines. A comprehensive REDCap electronic survey sought responses from directed (n = 20) and listserv elicited (n = 108) endourologists specializing in kidney stone disease. Questions included which clinical scenarios prompt a stone culture order, how results influence post-operative antibiotics, and what microbiology lab protocols exist at each institution with respect to processing and resulting stone cultures. Logistic regression statistical analysis determined what factors were associated with performing stone cultures. Of 128 unique responses, 11% identified as female and the mean years of practicing was 16 (range 1-46). A specific 'stone culture' order was available to only 50% (64/128) of those surveyed, while 32% (41/128) reported culturing stone by placing a urine culture order. The duration of antibiotics given for a positive stone culture varied, with 4-7 days (46%) and 8-14 days (21%) the most reported. More years in practice was associated with fewer stone cultures ordered, while higher annual volume of percutaneous nephrolithotomy was associated with ordering more stone cultures (p < 0.01). Endourologists have differing practice patterns with respect to ordering stone cultures and utilizing the results to guide post-operative antibiotics. With inconsistent microbiology lab stone culture protocols across multiple institutions, more uniform processing is needed for future studies to assess the clinical benefit of stone cultures and direct future guidelines.

Preoperative Midstream Urine Cultures vs Renal Pelvic Urine Culture or Stone Culture in Predicting Systemic Inflammatory Response Syndrome and Urosepsis After Percutaneous Nephrolithotomy: A Systematic Review and Meta-Analysis

Purpose: To compare preoperative midstream urine cultures (PMUC) and renal pelvic urine culture (RPUC) or stone culture (SC) in predicting systemic inflammatory response syndrome (SIRS) and urosepsis after percutaneous nephrolithotomy (PCNL). Methods: We searched the PubMed, Web of Science, and EMBASE databases up to September 1, 2020, for relevant published studies. Two authors independently confirmed whether the literatures met the inclusion criteria and collected the data from the selected literatures. A meta-analysis was performed with Review Manager Software 5.4.1. A total of 14 studies with 3540 patients were selected and analyzed in the meta-analysis. Results: Pooled data showed that SC was associated with a higher sensitivity (odds ratios [OR] 2.36, confidence interval [95% CI] 1.31-4.25; p < 0.00001), positive predictive value (PPV) (OR 1.54, 95% CI 1.18-2.01; p = 0.16) and negative predictive values (OR 1.17, 95% CI 1.01-1.37; p = 0.06) in the diagnosis of SIRS and urosepsis after PCNL, and RPUC provided a significantly higher specificity (OR 2.70, 95% CI 2.16-3.38; p = 0.07) and PPV (OR 2.17, 95% CI 1.49-3.15; p = 0.48) than PMUC in the diagnosis of SIRS and urosepsis after PCNL. Conclusion: Intraoperative SC and RPUC are more reliable than PMUC in predicting postoperative SIRS and urosepsis, identifying causative organisms, and directing antibiotic therapy for patients who underwent PCNL. PMUC, SC, and RPUC should be routinely collected for the diagnosis and management of SIRS and urosepsis after PCNL.

Assessing the optimal urine culture for predicting systemic inflammatory response syndrome after percutaneous nephrolithotomy and retrograde intrarenal surgery: results from a systematic review and meta-analysis

Background Systemic inflammatory response syndrome (SIRS) is a dangerous complication after percutaneous nephrolithotomy (PCNL) and retrograde intrarenal surgery (RIRS). We aimed to review the diagnostic accuracy of mid steam urine culture (MSUC), pelvic urine culture (PUC) and stone culture (SC) derived from the same cases to predict SIRS after PCNL and/or RIRS. Materials and methods A comprehensive literature search was performed, using MEDLINE, EMBASE, and Cochrane Central Controlled Register of Trials. Sensitivity and specificity were calculated for MSUC, PUC, and SC. The diagnostic odds ratio (DOR) was estimated for each study with a random effect and hierarchical summary receiver operating characteristic (HSROC) model leading to a corresponding 95% Confidence Interval (CI). Overall test accuracy was measured by finding the area under the curve (AUC). An AUC value >0.70 stands for adequate overall accuracy Results The search retrieved 537 papers. After screening, 21 studies involving 5238 patients were included for the meta-analysis. The pooled sensitivity for MSUC was 0.322 (95% CI 0.2228-0.432), and pooled specificity 0.854 (95% CI 0.810-0.889). The DOR was low at 2.780 (95% CI 1.769-4.368), showing poor overall diagnostic accuracy. The pooled sensitivity for PUC was 0.323 (95% CI 0.224-0.440) and specificity 0.931 (95% CI 0.896-0.954). The DOR was 6.377 (95% CI 4.065-10.004), showing a mild overall diagnostic accuracy. The pooled sensitivity for SC was 0.552 (95% CI 0.441-0.658) and specificity 0.847 (95%CI 0.798-0.886). The DOR was 6.820 (95%CI 4.435-10.488), showing mild overall diagnostic accuracy. The AUC for HSROC for MSUC was 0.65, 0.73, and 0.75 for PUC and SC, respectively. Conclusion MSUC is a poor predictor for postoperative SIRS. PUC or SC should be collected during lithotripsy to better predict the possibility of developing postoperative SIRS after PCNL and RIRS.

Feasibility and relevance of urine culture during stone fragmentation in patients undergoing percutaneous nephrolithotomy and retrograde intrarenal surgery: a prospective study

PURPOSE

We evaluated if, during lithotripsy, bacteria may be detected in the irrigation fluid of percutaneous nephrolithotomy (PCNL) and retrograde intrarenal surgery (RIRS). The concordance between urine culture from stone fragmentation (SFUC), bladder (BUC), renal pelvic (RPUC) and stone (SC) was analyzed. We also assessed the correlation between variables and cultures and their association with systemic inflammatory response syndrome (SIRS) and of a positive SC.

METHODS

We included 107 patients who underwent PCNL (n = 53) and RIRS (n = 54) from January 2017 to May 2018. Samples for RPUC were obtained by renal catheterization. Stone fragments and irrigation fluid sample were sent for culture.

RESULTS

SFUC was positive in 17 (15.9%), BUC in 22 (20.6%), RPUC in 26 (24.3%) and SC in 30 patients (28%). The concordance between SFUC and SC was the highest among all cultures: 94.1%. SFUC and SC grew identical microorganisms in 15/17 (88.2%) patients. Out of 17 (15.9%) patients with SIRS, 8 (7.5%) had sepsis. SFUC had the highest PPV and specificity to detect positive SC and SIRS. Previous urinary tract infection, a preoperative nephrostomy, stone diameter and composition, staghorn calculi, PCNL, positive BUC, RPUC and SFUC were predictors of infected stone. Variables that indicate complex stones, complex PCNL and an infection of the upper tract were associated with SIRS.

CONCLUSION

SFUC is technically feasible, easy to retrieve and to analyze. The spectrum of SFUC potential application in clinical practice is when is not possible to perform a SC, e.g. complete dusting or during micro-PCNL.

An evaluation of multidrug-resistant (MDR) bacteria in patients with urinary stone disease: data from a high-volume stone management center

PURPOSE

To investigate the prevalence of MDR bacteria in patients with urinary stones and the risk factors for its formation.

METHODS

A retrospective study was performed among patients with urinary stones in Beijing Tsinghua Changgung Hospital from December 2014 to May 2018. Patients with positive urinary cultures and drug sensitivity results were included. MDR were defined as any bacteria that have resistance to at least one agent in at least three classes of antibiotics. Bacteria distribution and resistance patterns were calculated.

RESULTS

1655 patients with urinary stones were eligible for analysis, among which 367 patients had positive urinary culture, yielding 457 isolates of 45 species. Escherichia coli remained the most common organism with a prevalence of 29.3%, followed by Enterococcus faecalis (12.0%), Proteus mirabilis (10.5%), and Klebsiella pneumonia (6.8%). 44.4% isolates were identified as MDR. The three most common Gram-negative bacteria were Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae, with a MDR rate of 84.33%, 62.5%, and 48.39%, respectively. Drug-resistant rates were different between MDR and non-MDR in ampicillin, cefazolin, ceftriaxone, cefepime, gentamicin, amikacin, and levofloxacin (all with p value < 0.05). In multivariate analysis, indwelling catheters (OR 3.1, 95% CI 1.07-8.98) and antibiotics use in the last 3 months (OR 2.14, 95% CI 1.04-4.38) were significantly associated with MDR formation.

CONCLUSIONS

MDR bacteria were common among patients with urinary stones in our center and achieved high drug-resistant rates in ampicillin, first-generation and part of third-generation cephalosporins, and fluoroquinolones. Indwelling catheters and antibiotics used in the last 3 months were independent risk factors for MDR formation. Tailored antibacterial strategies still should be established according to the local bacterial spectrum and patient condition.

Predicting the risk of sepsis and causative organisms following urinary stones removal using urinary versus stone and stent cultures

The association between foreign objects in the urinary system and urinary tract infections (UTI) is well established. The incidence of bacteriuria in patient with urinary catheters increases as dwelling time lengthens. The presence of ureteral stents and kidney stones is also associated with increased risk for bacteriuria and urinary tract infection. The aim of this study was to assess the bacterial characteristics of urine culture (UC) and foreign body culture (FBC), the concordance between them, and to identify risk factors for postoperative infections, in order to improve the treatment in these patients, using a prospectively collected database of patients who underwent ureteroscopy or percutaneous nephrolithotomy (PCNL) for the treatment of urinary stones between 2005 and 2016 at our institute. Preoperative UC was obtained from voided mid-stream urine for all patients. FBCs were obtained from ureteral stents removed and stones collected during the surgery. The cohort included 1011 patients. Mean age was 53 (SD 15.8), and 679 (67.2%) patients were male. Two hundred eighteen (21.6%) had a UTI in the year prior to the surgery. Among 795 patients who had sterile UC, 98 (12.3%) patients had positive FBC. Positive FBC was found in 53.7% of the patients with positive UC; however, FBC pathogens were similar to those identified in UC in 31% patients. The sensitivity of UC to detect FBC pathogens was 31.3%, and the PPV was 0.31. Urine cultures do not recognize all cases of pathogens colonizing foreign bodies in the urinary system. The colonization may be associated with an increased risk for SIRS. In more than one-quarter of the patients, the causative pathogen of sepsis is identified by FBC, but not by UC.

Characterization of Flow-Caused Intrarenal Pressure Conditions During Percutaneous Nephrolithotomy In Vitro

PURPOSE

To investigate renal pelvic pressures during percutaneous nephrolithotomy (PCNL) in the standard, mini, and ultramini PCNL systems.

METHODS

We studied an ultramini PCNL system (UMP, outer shaft diameter 13F), a mini PCNL system (MPCNL, shaft 18F, nephroscope 12F), and a standard PCNL system (SPCNL, shaft 27F, nephroscope 24F). Pressure profiles were first investigated in an open model setup, subsequently in a closed model, and finally in an ex vivo porcine kidney. Measurements were determined with the nephroscope in an advanced and pulled-back position for all models.

RESULTS

In the advanced position, maximum pressures of 41.61 ± 0.20 mmHg (UMP), 15.61 ± 0.15 mmHg (MPCNL), and 15.46 ± 0.14 mmHg (SPCNL) were measured in the closed model. In the pulled-back position, maximum pressures were 16.04 ± 0.22 mmHg (UMP), 17.02 ± 0.11 mmHg (MPCNL), and 20.50 ± 0.11 mmHg (SPCNL). In the ex vivo porcine kidney model, maximum pressures were 13.81 ± 6.04 mmHg (UMP), 5.64 ± 0.21 (MPCNL), and 9.21 ± 0.52 (SPCNL) with the nephroscope pushed to end position. After retracting the nephroscope from the outer shaft, pressures in all systems did not exceed 10 mmHg.

CONCLUSIONS

The maximum pressures achieved with the three PCNL systems in all three models were kept below the 30 mmHg critical threshold value. High pressures were only determined for the UMP system with the nephroscope pushed to its end position. This was attributed to the conical shape of the nephroscope, which occupies the space between the nephroscope and outer shaft, resulting in outflow obstruction.

Efficacy of Intraoperative Renal Stone Culture in Predicting Postpercutaneous Nephrolithotomy Urosepsis/Systemic Inflammatory Response Syndrome: A Prospective Analytical Study with Review of Literature

AIM

To evaluate and study the efficacy of intraoperative renal stone culture (IOSC) in predicting postpercutaneous nephrolithotomy (PCNL) urosepsis (PPS) and systemic inflammatory response syndrome (SIRS). PPS is known to occur in patients despite negative preoperative midstream urine culture (MSUC).

METHODS

After obtaining institutional ethics committee approval and informed consent, 78 selected patients undergoing PCNL were evaluated as per protocol for risk factors for SIRS criteria with MSUC, intraoperative renal pelvic urine culture (RPUC), and IOSC.

RESULTS

MSUC was positive in six (7.7%) patients. The sensitivity, specificity, PPV, negative predictive value (NPV) and respiratory rate of MSUC for detecting SIRS were 20%, 93.15, 16.67%, 94.44%, and threefold, respectively. RPUC was positive in five (6.9%) patients with a specificity and NPV of 92.64% and 94.02%, respectively. IOSC positivity was seen in four (5.1%) patients with specificity and NPV of 94.5% and 3.2%, respectively. SIRS developed in five (6.4%) patients. MSUC, RPUC, and IOSC could not demonstrate any significant association with the occurrence of SIRS. Postoperative urine culture (POUC) was positive in 1/5 SIRS patients and no significant association (p < 0.182) could be demonstrated between the risk factors and PPS. Most complications were minor, while the mean hospital stay was significantly higher in SIRS patients.

CONCLUSIONS

While MSUC, RPUC, and IOSC were less sensitive in predicting the occurrence of SIRS/urosepsis in patients undergoing PCNL, nevertheless, we recommend routine IOSC for stone colonizing bacteria in at-risk select patients to predict potential PPS/SIRS. POUCs could be used in symptomatic SIRS to guide antimicrobial therapy in post-PCNL patients. Positive peri/intraoperative urine cultures may assist the urologist in directing appropriate antibiotics to prevent potential urosepsis in post-PCNL patients. Those with a higher blood transfusion rate and Clavien complications were at increased risk of PPS/SIRS. Escherichia coli was the most frequently isolated microbe followed by Klebsiella and Proteus, which were mostly sensitive to nitrofurantoin.