Composition of urinary calculi related to urinary tract infection

Successful ureteroscopy for kidney stone disease leads to resolution of urinary tract infections: Prospective outcomes with a 12-month follow-up

Introduction

To investigate the resolution of urinary tract infection (UTI) with the successful treatment of kidney stone disease (KSD).

We reviewed the outcomes of ureteroscopy (URS) and stone treatment for patients with positive urine culture or recurrent UTIs and evaluated whether the infection resolved with the clearance of their urinary stones.

Material and methods

Between March 2012 and July 2016, consecutive patients who underwent URS for stone disease with a history of recurrent UTIs or culture proven UTIs were identified from a prospective database. Data was recorded on stone free rate (SFR) and infection free rate (IFR) during the follow-up period at 3, 6 and 12-months.

Results

During the study period, 103 consecutive patients with stone disease and associated UTI underwent URS over a 52-month period (mean age: 60 years, Female: Male ratio of 2:1). The mean cumulative stone size was 16 mm (range: 3–107 mm) and a positive pre-operative urine culture was found in 81 (79%) patients. While the overall SFR was 96%, the total complication rate was 12.6% (n = 13) and these were all Clavien I/II complications.

At follow-up, the SFR and IFR was 96% and 88% at 3-months, and 82% and 71% at 12-months, respectively (p <0.001). While almost three-quarters of patients were stone and infection free at 12-months, the majority of those with stones recurrence also had recurrence of their UTI.

Conclusions

The majority of patients will remain infection free at the 12-month follow-up if they are stone free after their initial treatment. Stone recurrence, which is more likely in high-risk patients, is also linked to the recurrence of their UTI.

A Multi-Institutional Study of Struvite Stones: Patterns of Infection and Colonization

OBJECTIVE

To examine urine and stone bacteriology of struvite stone formers in a large cohort of patients undergoing percutaneous nephrolithotomy (PCNL).

MATERIALS AND METHODS

A total of 1191 patients, with stone and urine cultures, treated with PCNL for renal calculi were included in the study. Statistical differences were assessed using Mann-Whitney U and T-tests.

RESULTS

Stone cultures were positive in 72% of patients with struvite stones. Urea-splitting organisms accounted for only half of the positive stone cultures. Enterococcus (9/50, 18%), Proteus (9/50, 18%), and Escherichia coli (6/50, 12%) were the most commonly identified organisms. Notably, two-thirds of struvite formers with negative stone culture had at least one positive culture for a urea-splitting organism on urine culture going back 1 year from the time of surgery. A majority (67%) of struvite stone cultures were found to be resistant to first- and second-generation cephalosporins.

CONCLUSIONS

The bacteriology of struvite stones has shifted away from traditional urea-splitting organisms and antibiotic coverage must be expanded to include organisms such as Enterococcus that do not respond to cephalosporins. Causative organisms may be found by going back in time to identify the initial organism that could have induced struvite stone formation to inform preventative therapy.

Gas-containing renal stones: findings from five consecutive patients

OBJECTIVE

To describe the clinical course, microbiology, and metabolic findings of 5 patients presenting to our institution with gas-containing renal stones.

MATERIALS AND METHODS

During a 20-month period beginning in 2009, 5 patients were identified by computed tomography scanning to harbor gas-containing renal calculi. Despite similar imaging and referral practice patterns, no such cases had been seen at our institution in the preceding 20 years. The records of these patients were reviewed to better characterize this unique condition.

RESULTS

All 5 subjects were premenopausal women. One patient presented with urosepsis and 4 presented with flank pain. All had urinary tract infections, and Escherichia coli was isolated from a voided urine specimen in 3. Stone culture was positive in 2 and was concordant with the voided specimen in 1. The stones were solitary in 4 and multiple in 1 patient. All the stones were composed of calcium phosphate. Of the 5 patients, 3 had pure calcium phosphate stones and 2 had stones with calcium oxalate monohydrate components. Also, 3 subjects had diabetes mellitus, 3 had hypertension, and 1 had a history of gout. Two subjects underwent 24-hour urine metabolic testing, and abnormalities were identified in both. All patients were rendered stone free: 4 with percutaneous nephrostolithotomy and 1 using robotic pyelolithotomy.

CONCLUSION

Gas-containing renal stones are rare but might be increasing in prevalence. The pathophysiology is unknown but is most likely influenced by a combination of metabolic and infectious factors.

Role of bacteria in oncogenesis

Although scientific knowledge in viral oncology has exploded in the 20th century, the role of bacteria as mediators of oncogenesis has been less well elucidated. Understanding bacterial carcinogenesis has become increasingly important as a possible means of cancer prevention. This review summarizes clinical, epidemiological, and experimental evidence as well as possible mechanisms of bacterial induction of or protection from malignancy.

Impact of citrate therapy on the circadian rhythm of urinary magnesium ammonium phosphate saturation in normal individuals

BACKGROUND

Alkaline citrate has been used widely in the prevention of stone formation. However, the risk of struvite stone during the alkalinizing therapy has not been adequately studied in terms of magnesium ammonium phosphate saturation.

METHODS

The circadian rhythm of the urinary saturation of magnesium ammonium phosphate was estimated by using the differential Gibbs' free energy values of magnesium ammonium phosphate before and during 5 days of treatment with sodium-potassium citrate (1 g t.i.d., 1 g q.i.d. or 3 g t.i.d.) in five healthy male volunteers.

RESULTS

The magnesium ammonium phosphate saturation varied during the day, peaking far below the solubility product between 08.00 and 10.30 h and between 13.00 and 18.00 h. The mean peak levels were increased by each treatment regimen in comparison with the control day. The mean increase on day 1 was significant between 10.30 and 23.00 h with the 3 g t.i.d. regimen, but the mean saturation still remained below the solubility product throughout the day.

CONCLUSIONS

The urinary magnesium ammonium phosphate saturation appeared hard to exceed the solubility product with a high dose of alkaline citrate.

Crystalline phase differentiation in urinary calcium phosphate and magnesium phosphate calculi

Phosphates are encountered as the main components in about 15% of urinary calculi. Except for struvite, no specific correlations have been found between the crystalline phase of the phosphates and the cause of nephrolithiasis.

OBJECTIVE

The relationship between aetiological factors and crystalline phases or carbonate rate in calcium phosphate stones were assessed.

MATERIAL AND METHODS

From a series of 1148 phosphate calculi, we investigated the relationship between composition and aetiological factors.

RESULTS

Carbapatite was the most frequent crystalline phase (74.0%). It was associated with many possible causes, including hypercalciuria, hypocitraturia, primary hyperparathyroidism, tubular acidosis, medullary sponge kidney and chronic urinary tract infection. The carbonate rate of carbapatite may be of clinical interest because carbonate rates above 15% are frequently related to urinary tract infection with urea-splitting bacteria. Conversely, the carbonate rate was commonly less than 10% in cases of carbapatite induced by metabolic disorders. Among other phosphates, brushite was found in hypercalciuric states and primary hyperparathyroidism and whitlockite in cases of urinary tract infection by non-urease-producing bacteria.

CONCLUSION

Identification of crystalline phases and measurement of carbonate rate in calcium phosphate calculi is of clinical interest for identifying stone aetiology.

Percutaneous nephrostolithotomy. What is its role in 1997?

PNL is a challenging and satisfying part of endourologic practice. Although more invasive than SWL or ureteroscopy, it offers a high chance of success in many different situations. The selective and appropriate application of PNL requires the consideration of many factors, especially stone location and size, patient habitus, and the anatomy of the upper urinary tract (Table 5). For the urologic surgeon in the last decade of the twentieth century, complete stone therapy entails judgment and skill with myriad modalities: SWL, ureteroscopy, PNL, and open or laparoscopic stone surgery.

Estimated levels of supersaturation with calcium phosphate and calcium oxalate in the distal tubule

Approximate estimates of the ion-acitivity products of calcium phosphate and calcium oxalate in distal tubular urine were derived from the 16-h urinary excretion of calcium, oxalate, citrate, magnesium and phosphate. Urine variables were obtained from 96 normal subjects and 277 calcium stone formers and the calculations were carried out with iterative approximation using the EQUIL2 program. With respect to other ions of importance for the ion-activity products, the urine was assumed to have a fixed composition with pH 6.45. Significantly higher ion-activity products of both calcium phosphate and calcium oxalate were recorded in stone formers. It was concluded that diurnal variations in urine composition and pH might result in peaks of calcium phosphate supersaturation in distal tubular urine whereby a crystallization can occur. In association with abnormalities in terms of promotion and inhibition of calcium salt crystallization, such a precipitation can be of importance for the subsequent formation of calcium renal stones.

Human bladder cancer: evidence for a potential irritation-induced mechanism

Bladder cancer is one of the most common human cancers, constituting about 6% and 2% of all cancers among males and females, respectively. Over 90% of all bladder cancers are transitional cell carcinomas, with most of the remainder being squamous cell carcinomas. Smoking and occupational exposure to aromatic amines and other agents are most prominent among the risk factors identified. Inflammation of the bladder, largely by infection but also by stones or a combination of the two, may play some role in human bladder cancer development. The association between inflammation and cancer appears to be stronger for squamous cell than for transitional cell carcinoma. Stones and infection can be important factors in the development of bladder tumours in rodents, but the tumours are predominantly transitional cell rather than squamous cell carcinomas.