Antibiotic treatment-induced tubular dysfunction as a risk factor for renal stone formation in cystic fibrosis

Standards for the care of people with cystic fibrosis (CF); recognising and addressing CF health issues

This is the third in a series of four papers updating the European Cystic Fibrosis Society (ECFS) standards for the care of people with CF. This paper focuses on recognising and addressing CF health issues. The guidance was produced with wide stakeholder engagement, including people from the CF community, using an evidence-based framework. Authors contributed sections, and summary statements which were reviewed by a Delphi consultation. Monitoring and treating airway infection, inflammation and pulmonary exacerbations remains important, despite the widespread availability of CFTR modulators and their accompanying health improvements. Extrapulmonary CF-specific health issues persist, such as diabetes, liver disease, bone disease, stones and other renal issues, and intestinal obstruction. These health issues require multidisciplinary care with input from the relevant specialists. Cancer is more common in people with CF compared to the general population, and requires regular screening. The CF life journey requires mental and emotional adaptation to psychosocial and physical challenges, with support from the CF team and the CF psychologist. This is particularly important when life gets challenging, with disease progression requiring increased treatments, breathing support and potentially transplantation. Planning for end of life remains a necessary aspect of care and should be discussed openly, honestly, with sensitivity and compassion for the person with CF and their family. CF teams should proactively recognise and address CF-specific health issues, and support mental and emotional wellbeing while accompanying people with CF and their families on their life journey.

Systematic Review of the Prevalence of Kidney Stones in Cystic Fibrosis

Purpose: To investigate the prevalence of urolithiasis in cystic fibrosis (CF) and to summarize the available clinical features within this unique population. Methods: Studies reporting the prevalence of urolithiasis in CF patients were identified by a systematic search of the literature from inception to July 31, 2020 on three databases: Ovid Medline, Ovid Embase, and Web of Science. Data were extracted on a predetermined standardized form by two independent authors. Results: A total of 596 publications were retrieved and screened, 15 of which met the eligibility criteria. The publications were published between 1993 and 2019 and were all observational in design. There was a total of 2982 patients with CF included in this review. The overall prevalence of stone formation in the CF population was 4.6% (137/2982). The mean age of diagnosis was 25.1 ± 9.6 and ranged from 0.25 to 47. Ultrasound was the most common imaging modality for kidney stone diagnosis. There was no apparent sex difference, with a female to male ratio of 1:1. Surgical intervention was required in 37.8% (34/90) of cases. Stone recurrence was reported in 42.9% (33/77) of stone formers. Conclusions: This review provides the most recent update for the prevalence of urolithiasis in CF patients and summarizes the available clinical data. Our findings suggest that patients with CF could be at risk for developing stones at a younger age and require interventional management strategies at higher rates compared with the general population. Given the heterogeneity of the literature for urolithiasis in CF, larger population-based studies reporting the epidemiology, clinical features, and management strategies are required to further our understanding of urolithiasis in CF.

Urinary stone disease prevalence and associations in cystic fibrosis

Cystic fibrosis (CF) may predispose patients to urinary stone disease (USD), but reported prevalence of USD in patients with CF in previous small studies is variable. To date, analysis of risk factors for USD within the CF population has been limited. We studied 29,396 patients in the Cystic Fibrosis Foundation Patient Registry to calculate age and sex-stratified prevalence of USD. For adult patients, we examined age and multivariable-adjusted cross-sectional associations between demographic and clinical factors, CFTR mutation class, and prevalent USD. Prevalence of USD was 0.4% (95% CI 0.3-0.5%) under age 18 years, 3.1% (2.7-3.6%) at 18-24 years, 6.4% (5.8-7.1%) at 25-34 years, 7.5% (6.5-8.5%) at 35-44 years, and 6.7% (5.8-7.8%) at 45 years and older. Prevalence for women was higher than men at younger (< 45 years) but not older ages (P value for interaction < 0.0005). Multivariable odds of prevalent USD were significantly increased for severe CFTR mutations, OR 1.53 (1.14-2.06), diabetes, OR 1.24 (1.03-1.50), hypertension, OR 1.58 (1.29-1.93), and chronic macrolide therapy, OR 1.27 (1.07-1.52). BMI was not associated with USD. USD prevalence in CF is similar to that in the general population. With the exception of BMI, known risk factors for USD in the general population also appear to be important for patients with CF. We identified several novel associations in CF patients, including greater prevalence of USD in individuals with severe CFTR mutations and among young women.

Drug-Induced Urolithiasis in Pediatric Patients

Drug-induced nephrolithiasis is a rare condition in children. The involved drugs may be divided into two different categories according to the mechanism involved in calculi formation. The first one includes poorly soluble drugs that favor the crystallization and calculi formation. The second category includes drugs that enhance calculi formation through their metabolic effects. The diagnosis of these specific calculi depends on a detailed medical history, associated comorbidities and the patient's history of drug consumption. There are several risk factors associated with drug-induced stones, such as high dose of consumed drugs and long duration of treatment. Moreover, there are some specific risk factors, including urinary pH and the amount of fluid consumed by children. There are limited data regarding pediatric lithogenic drugs, and hence, our aim was to perform a comprehensive review of the literature to summarize these drugs and identify the possible mechanisms involved in calculi formation and discuss the management and preventive measures for these calculi.

Antibiotic Use and Risk of Incident Kidney Stones in Female Nurses

RATIONALE & OBJECTIVE

The intestinal microbiome may affect urinary stone disease by modulating the amount of oxalate absorbed from the intestine and subsequently excreted in urine. This study sought to explore the association between antibiotics, which alter the intestinal microbiota, and risk for urinary stone disease.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

5,010 women in the Nurses' Health Study (NHS) I and II who had collected 24-hour urine samples.

EXPOSURES

Use of antibiotics during the age range of 40 to 49 (NHS II), 40 to 59 (NHS I), and 20 to 39 years (both cohorts).

OUTCOMES

Incident symptomatic urinary stone disease; urine composition.

ANALYTICAL APPROACH

Cause-specific hazards regression adjusted for age, body mass index, comorbid conditions, thiazide use, and dietary factors. Follow-up was censored at the time of asymptomatic kidney stones, cancer, or death.

RESULTS

Cumulative use of antibiotics for a total of 2 or more months during the age range of 40 to 49 years (NHS II) and 40 to 59 years (NHS II) was associated with significantly higher risk for developing incident stones compared with no use (pooled HR, 1.48; 95% CI, 1.12-1.96). Similar results were found for the period of 20 to 39 years (pooled HR, 1.36; 95% CI, 1.00-1.84). Results were unchanged after excluding participants who reported urinary tract infection with their stone event or as the most common reason for antibiotic use. Urine composition was generally similar across antibiotic groups except for marginally lower urine pH and citrate values among those taking antibiotics for 2 or more months.

LIMITATIONS

Observational design; lack of information for type of antibiotic used; relatively large span of time between antibiotic use and urine collection.

CONCLUSIONS

Use of antibiotics for more than 2 months in early adulthood and middle age is associated with higher risk for urinary stone disease in later life.

Drug-Induced Kidney Stones and Crystalline Nephropathy: Pathophysiology, Prevention and Treatment

Drug-induced calculi represent 1-2% of all renal calculi. The drugs reported to produce calculi may be divided into two groups. The first one includes poorly soluble drugs with high urine excretion that favour crystallisation in the urine. Among them, drugs used for the treatment of patients with human immunodeficiency, namely atazanavir and other protease inhibitors, and sulphadiazine used for the treatment of cerebral toxoplasmosis, are the most frequent causes. Besides these drugs, about 20 other molecules may induce nephrolithiasis, such as ceftriaxone or ephedrine-containing preparations in subjects receiving high doses or long-term treatment. Calculi analysis by physical methods including infrared spectroscopy or X-ray diffraction is needed to demonstrate the presence of the drug or its metabolites within the calculi. Some drugs may also provoke heavy intra-tubular crystal precipitation causing acute renal failure. Here, the identification of crystalluria or crystals within the kidney tissue in the case of renal biopsy is of major diagnostic value. The second group includes drugs that provoke the formation of urinary calculi as a consequence of their metabolic effects on urinary pH and/or the excretion of calcium, phosphate, oxalate, citrate, uric acid or other purines. Among such metabolically induced calculi are those formed in patients taking uncontrolled calcium/vitamin D supplements, or being treated with carbonic anhydrase inhibitors such as acetazolamide or topiramate. Here, diagnosis relies on a careful clinical inquiry to differentiate between common calculi and metabolically induced calculi, of which the incidence is probably underestimated. Specific patient-dependent risk factors also exist in relation to urine pH, volume of diuresis and other factors, thus providing a basis for preventive or curative measures against stone formation.

Loss of Cystic Fibrosis Transmembrane Regulator Impairs Intestinal Oxalate Secretion

Patients with cystic fibrosis have an increased incidence of hyperoxaluria and calcium oxalate nephrolithiasis. Net intestinal absorption of dietary oxalate results from passive paracellular oxalate absorption as modified by oxalate back secretion mediated by the SLC26A6 oxalate transporter. We used mice deficient in the cystic fibrosis transmembrane conductance regulator gene (Cftr) to test the hypothesis that SLC26A6-mediated oxalate secretion is defective in cystic fibrosis. We mounted isolated intestinal tissue from C57BL/6 (wild-type) and Cftr^-/- mice in Ussing chambers and measured transcellular secretion of [¹⁴C]oxalate. Intestinal tissue isolated from Cftr^-/- mice exhibited significantly less transcellular oxalate secretion than intestinal tissue of wild-type mice. However, glucose absorption, another representative intestinal transport process, did not differ in Cftr^-/- tissue. Compared with wild-type mice, Cftr^-/- mice showed reduced expression of SLC26A6 in duodenum by immunofluorescence and Western blot analysis. Furthermore, coexpression of CFTR stimulated SLC26A6-mediated Cl^--oxalate exchange in Xenopus oocytes. In association with the profound defect in intestinal oxalate secretion, Cftr^-/- mice had serum and urine oxalate levels 2.5-fold greater than those of wild-type mice. We conclude that defective intestinal oxalate secretion mediated by SLC26A6 may contribute to the hyperoxaluria observed in this mouse model of cystic fibrosis. Future studies are needed to address whether similar mechanisms contribute to the increased risk for calcium oxalate stone formation observed in patients with cystic fibrosis.

Management of urinary tract infections associated with nephrolithiasis

Nephrolithiasis is a common clinical entity, and the incidence of renal stones appears to be increasing in the United States. Infection with uropathogens that produce urease can lead to the development of stones (infection stones), which serve as a continued source of recurrent infection and can lead to chronic kidney disease. Other than treating infection, medical management has little role in the treatment of infection stones; complete eradication of the stones with percutaneous nephrolithotomy or extracorporeal shock wave lithotripsy is required. Stones of metabolic origin can cause obstruction in the ureter and predispose to the development of urinary tract infection (UTI). Recognizing obstruction and initiating prompt drainage of the collecting system is important in the successful management of nephrolithiasis complicated by UTI. These patients are often at high risk of infection with an antimicrobial-resistant pathogen, so careful consideration of antimicrobial therapy is required, especially for patients who present with severe sepsis.

Renal impairment in children with cystic fibrosis

BACKGROUND

Due to the improvement in life expectancy in cystic fibrosis (CF), co-morbidities such as renal function impairment may be more frequent.

AIM

To determine the prevalence of renal disease in children with CF and to identify associated risk factors.

METHODS

A single-center retrospective study analyzing the genetic, clinical and therapeutic characteristics of 112 children. The estimated glomerular filtration rate (GFR), microalbuminuria and lithiasic risk factors were assessed.

RESULTS

The median calculated GFR (Schwartz) was 123, 161 and 155ml/min/1.73m(2) in children aged 1, 6 and 15years, respectively. The cumulative dose of aminoglycosides was not correlated to GFR. Microalbuminuria was present in 22/38 patients. Hyperoxaluria was observed in 58/83 patients and was associated with a severe genotype, pancreas insufficiency and liver disease. Hypercalciuria, hyperuricuria and hypocitraturia were identified in 16/87, 15/83 and 57/76 patients, respectively.

CONCLUSION

Renal impairment in CF has various presentations. There appears to be low levels of renal impairment in children with CF. However, the risk of oxalocalcic urolithiasis is enhanced, and GFR may be underestimated by the Schwartz formula. Further studies using measured GFR techniques are thus warranted.

Factors increasing the risk for stone formation in adult patients with cystic fibrosis

BACKGROUND

Patients with cystic fibrosis (CF) are at high risk of nephrolithiasis (NL), but controversy still exists in terms of causes, including low urine output, hypercalciuria, hyperoxaluria, hyperuricosuria and hypocitraturia. Moreover, heterozygotes (H-CF), which may exhibit altered renal concentrating and diluting ability, have never studied so far. We, therefore, evaluated the metabolic and physicochemical data of adult CF and H-CF patients, comparing them to controls (C).

METHODS

Twenty-nine CF patients (16 females, aged 28.4 +/- 7.1 years), 20 H-CF (12 females, aged 58.6 +/- 6.3 years) and 30 C (19 females, aged 39.1 +/- 11.5 years) underwent kidney ultrasound and metabolic evaluation to assess stone risk profile.

RESULTS

There was a 21% prevalence of NL in CF vs 15% in H-CF. The CF group had elevated uric acid, but no other serological differences compared with the H-CF and C group. Conversely, the citrate and oxalate content in the urine differed significantly, being lower and higher, respectively. These changes held after correction for urine creatinine. Consequently, urine specimens were more supersaturated with calcium oxalate, despite exhibiting no differences for other relevant constituents. Uric acid increased only after normalization for the body weight and urine creatinine. Lower urine volume and more acidic pH produced mild supersaturation with uric acid in samples from CF, while urine from both H-CF and C remained undersaturated. H-CF had only minor increases in both urine oxalate and calcium oxalate supersaturation.

CONCLUSIONS

This study confirms a high prevalence of kidney stones among CF patients associated with supersaturated urine. Their longer survival justifies diets and/or medications aimed at reducing the risk of forming stones.

Absorptive hyperoxaluria leads to an increased risk for urolithiasis or nephrocalcinosis in cystic fibrosis

BACKGROUND

Hyperoxaluria has been incriminated to account for the increased incidence of urolithiasis or nephrocalcinosis in patients with cystic fibrosis (CF). Hyperoxaluria presumably is caused by fat malabsorption and the absence of such intestinal oxalate-degrading bacteria as Oxalobacter formigenes. To better elucidate its pathophysiological characteristics, we prospectively studied patients with CF by determining these parameters and performing renal ultrasonography twice yearly.

METHODS

In addition to routine tests in urine (lithogenic and stone-inhibitory substances), the presence of O formigenes was tested in stool, plasma oxalate was measured, and a [13C2]oxalate absorption test was performed in 37 patients with CF aged 5 to 37 years (15 females, 22 males) who were constantly hyperoxaluric before the study.

RESULTS

Hyperoxaluria (oxalate, 46 to 141 mg/1.73 m2/24 h [0.51 to 1.57 mmol/1.73 m2/24 h]; normal, < 45 mg/1.73 m2/24 h [< 0.5 mmol/1.73 m2/24 h]) was now found in 24 patients (64.8%). Plasma oxalate levels were elevated in 6 patients (7.92 to 19.5 micromol/L; normal, 6.3 +/- 1.1 micromol/L). Oxalobacter species were detected in only 1 patient. Intestinal oxalate absorption was elevated (11.4% to 28.5%; normal, < 10%) in 23 patients. Hypocitraturia was present in 17 patients (citrate, 0.35 to 2.8 g/1.73 m2/24 h [0.2 to 1.1 mmol/1.73 m2/24 h]; normal female, > 2.8 mg/1.73 m2/24 h [> 1.6 mmol/1.73 m2/24 h]; male, > 3.3 mg/1.73 m2/24 h [> 1.9 mmol/1.73 m2/24 h]). Urine calcium oxalate saturation was elevated in 17 patients (5.62 to 28.9 relative units; normal female, < 5.5 relative units; male, < 6.3 relative units). In 16% of patients, urolithiasis (n = 2) or nephrocalcinosis (n = 4) was diagnosed ultrasonographically.

CONCLUSION

Absorptive hyperoxaluria and hypocitraturia are the main culprits for the increased incidence of urolithiasis and nephrocalcinosis in patients with CF. We advocate high fluid intake, low-oxalate/high-calcium diet, and alkali citrate medication, if necessary. Additional studies are necessary to determine the influence of Oxalobacter species or other oxalate-degrading bacteria on oxalate handling in patients with CF.

Antibiotic-related renal failure and cystic fibrosis

Recently published reports suggest that the combination of aminoglycosides with ceftazidime may increase the risk of renal disease in cystic fibrosis. We describe a case of unusually severe acute tubular necrosis occurring in an adolescent with cystic fibrosis receiving i.v. gentamicin plus ceftazidime and discuss the possible mechanisms.

Urolithiasis after kidney transplantation in pediatric recipients: a single center report

BACKGROUND

Urolithiasis occurs in approximately 6% of adult kidney transplant (KTx) recipients. Limited data are available on urolithiasis after pediatric KTx. We report the incidence, management of, and risk factors for stone development in children after KTx.

METHODS

We reviewed the medical records of 399 children who received KTx at our center between September 1986 and January 2003. Transplant outcomes were compared in stone formers and controls.

RESULTS

Twenty (5%) patients, age 9+/-5 (X +/- SD) years, developed stones over the follow-up period (74+/-53 months). Time to stone presentation was 19+/-22 months post-KTx. Presenting features were urinary tract infection (UTI), 8; gross hematuria, 5; microscopic hematuria, 2; dysuria without infection, 6; difficulty voiding, 3; and silent stones, 2. Stones were removed by cystoscopy in 11 (55%) patients. Stone composition was determined in 11 patients: calcium phosphate (55%), calcium oxalate (18%), mixed calcium phosphate and oxalate (9%), and struvite (18%). Factors predisposing to stones in study patients included suture retention (n = 4), elevated urinary calcium excretion (n = 2), recurrent UTI (n = 2), and urinary stasis (n = 2). The incidence of UTI was higher (P = 0.003) and of acute rejection was lower (P = 0.02) in stone patients compared with controls. Patient and graft survival rates and the incidence of chronic rejection did not significantly differ between study patients and controls (P = NS).

CONCLUSIONS

Urolithiasis is not uncommon in pediatric KTx patients. Factors associated with post-KTx urolithiasis include retention of suture material, recurrent UTI, hypercalciuria, and urinary stasis. Treatment is associated with excellent outcome and low recurrence rate.

Surgical management of children with urolithiasis

The management of urolithiasis in children poses specific technical challenges that require planning before endoscopy and that affect the risks and outcomes of these procedures. The indications for operative intervention in children and adults are similar:infection, persistent symptoms of flank pain, nausea, and vomiting, as well as the failure to pass a ureteral stone after an appropriate trial of observation (3-6 weeks). Specific adjustments for performing extracorporeal shock wave lithotripsy, ureteroscopy, percutaneous nephrolithotomy, and cystolithotomy in children are discussed.

[Urolithiasis in cystic fibrosis]

The prevalence of urolithiasis is higher in patients with cystic fibrosis than in the normal population. We report on a case of a 12-year-old child with cystic fibrosis who presented flank pain which revealed a calcium oxalate urolithiasis. Evolution was satisfactory with pharmacological and dietary treatment. The principal mechanisms of lithogenesis in patients with cystic fibrosis are described and preventive treatment is discussed.

The association of nephrolithiasis with cystic fibrosis

BACKGROUND

There is a growing body of evidence regarding the association between cystic fibrosis (CF) and nephrolithiasis and the role that Oxalobacter formigenes may have in that association.

METHODS

We performed a MEDLINE search of "cystic fibrosis and nephrolithiasis" and "Oxalobacter formigenes." Epidemiological and experimental evidence and possible mechanisms explaining the association were critically reviewed.

RESULTS

Of patients with CF, 3.0% to 6.3% are affected with nephrolithiasis, a percentage greater than that of age-matched controls without CF, in whom the rate is 1% to 2%. Studies have suggested possible mechanisms for the association, including hyperuricosuria, hyperoxaluria, primary defects in calcium handling caused by mutation of the CF transmembrane regulator (CFTR), hypocitraturia, and lack of colonization with O formigenes, an enteric oxalate-degrading bacterium. The absence of colonization could be related to frequent courses of antibiotics.

CONCLUSION

Although the incidence of stones in patients with CF may be increased compared with controls without CF, many possible mechanisms are implicated. The relative contributions of these mechanisms remain uncertain. Future directions may include specific identification of lithogenic risks and therapy aimed at stone prevention in this population.

Infection and urinary stones

PURPOSE OF REVIEW

Despite modern antibiotic therapy and technological advances in lithotripsy, the presence of infection in urinary stone patients as well as infectious stones are still a significant cause of morbidity and mortality. Many new investigations are focusing on the pathogenesis and treatment of these difficult cases.

RECENT FINDINGS

Most of the current literature on the subject focuses on pathogenesis of infectious urinary stones. The remaining literature highlights difficult cases, outcomes of treatments, and overall reviews of the subject.

SUMMARY

Recent findings lend more theories as to how infection leads to stone formation. Further investigation is critically needed to improve the outcomes of patients suffering from infections with urinary stones and infectious stones.