Diagnostic relevance of pyuria in dialysis patients

Urinary tract infections in patients with renal insufficiency and dialysis - epidemiology, pathogenesis, clinical symptoms, diagnosis and treatment

Epidemiological studies show an increasing number of patients worldwide suffering from chronic kidney diseases (CKD), which are associated with a risk for progression to end-stage kidney disease (ESKD). CKD patients stage 2-5, patients with regular chronic dialysis treatment (hemo- or peritoneal dialysis), and patients suffering from kidney allograft dysfunction are at high risk to develop infections, e.g. urinary tract infections (UTI) and/or sepsis (urosepsis). These groups show metabolic disturbance, chronic inflammation, and impaired immunocompetence. Escherichia coli is still the most common pathogen in UTI. A wide variety of other pathogens may be involved in UTI. Urological interventions, catheterization, as well as repeated courses of antibiotics contribute to an increased challenge of antimicrobial resistance. The diagnosis of UTI in CKD is based on standard clinical and laboratory criteria. Pyuria (≥10 leucocytes/µl) is more often observed in patients with oligoanuria and low bacterial colony counts. The treatment strategies for this population are based on the same principles as in patients with normal renal function. However, drugs cleared by the kidney or by dialysis membranes need dose adjustment. Antimicrobials with potential systemic toxicity and nephrotoxicity should be administered with caution.

Prevalence and Significance of Pyuria in Chronic Kidney Disease Patients in Saudi Arabia

Chronic kidney disease (CKD) is considered a major health problem, which poses a burden for health care systems worldwide. It has been estimated that 10% of the population worldwide have CKD; however, most of the cases are undiagnosed. If left untreated, CKD could lead to kidney failure, which highlights the importance of early diagnosis and treatment. Pyuria has been reported in CKD patients, and could be the result of several comorbidities, such as diabetes, or urinary tract infections (UTIs). A few studies have shown that pyuria is associated with the late stages of CKD. However, there are limited data on the prevalence of non-UTI (sterile) and UTI-pyuria in different CKD patient populations, and its association with the decline in kidney function and progression of CKD. In this retrospective study, we report the prevalence of pyuria (sterile and UTI) in 754 CKD patients of King Fahd Specialist Hospital, Buraydah, Saudi Arabia. Our data showed that 164/754 CKD patients (21.8%) had pyuria, whereas 590 patients (78.2%) presented with no pyuria. There was a significantly higher percentage of late-stage (stage 4) CKD patients in the pyuric group compared to the non-pyuric group (36.6% vs. 11.9%). In line with the previous data, proteinuria was detected in a significantly higher percentage of pyuric patients, in addition to significantly higher levels of serum creatinine and urea, compared to non-pyuric patients. Furthermore, 13.4% of the pyuric CKD patients had UTI, whereas 86.6% presented with sterile pyuria. E. coli was indicated as the causative agent in 45.5% of UTI patients. Our patient data analysis showed that a significantly higher percentage of UTI-pyuric CKD patients, than sterile pyuric patients (63.6% vs. 19.7%), had higher numbers of urinary white blood cells (>50/HPF, WBCs). The data also showed that a higher percentage of UTI-pyuric patients were late-stage CKD patients, compared to sterile pyuric patients (50% vs. 34.5%). Our findings indicate that a high level of pyuria could be considered as a marker for late-stage CKD, and that UTI is an important risk factor for the decline in kidney function and the progression to late-stage CKD. We believe that further studies are needed to correlate pyuria to kidney function, which could be helpful in monitoring the progression of CKD. Moreover, the management of comorbidities, such as diabetes and UTIs, which are risk factors for CKD and associated pyuria, could help to control the progression of CKD to the late stages.

Prevalence and Clinical Characteristics of Asymptomatic Pyuria in Chronic Kidney Disease

Background

Pyuria seems to be common in chronic kidney disease (CKD), irrespective of urinary tract infection (UTI). It has been hypothesized that sterile pyuria occurs in CKD because of chronic renal parenchymal inflammation. However, there are limited data on whether CKD increases the rate of pyuria or how pyuria in CKD should be interpreted. We investigated the prevalence and characteristics of asymptomatic pyuria (ASP) in CKD via urinary white blood cell (WBC) analysis.

Methods

Urine examination was performed for all stable hemodialysis (HD) and non-dialysis CKD patients of the outpatient clinic (total N=298). Patients with infection symptoms or recent history of antibiotic use were excluded. Urine culture and WBC analysis were performed when urinalysis revealed pyuria.

Results

The prevalence of ASP was 30.5% (24.1% in non-dialysis CKD and 51.4% in HD patients). Over 70% of the pyuria cases were sterile. The majority of urinary WBCs were neutrophils, even in sterile pyuria. However, the percentage of neutrophils was significantly lower in sterile pyuria. In multivariate logistic regression analysis, the degree of pyuria, percentage of neutrophils, and presence of urinary nitrites remained independently associated with sterile pyuria.

Conclusions

The prevalence of ASP was higher in CKD patients and increased according to CKD stage. Most ASP in CKD was sterile. Ascertaining the number and distribution of urinary WBCs may be helpful for interpreting ASP in CKD.

A single center, open-label, randomized, parallel group study assessing the relationship between asymptomatic bacteriuria and inflammation in maintenance hemodialysis patients

INTRODUCTION

The significance of asymptomatic bacteriuria in maintenance hemodialysis (MHD) patients remains controversial. We hypothesized that the presence of asymptomatic bacteriuria as a sole clinical manifestation of urinary tract infection (UTI) in asymptomatic MHD patient may contribute to the chronic inflammatory response. Our aim was to explore the relationship between asymptomatic bacteriuria and elevated levels of inflammatory markers in MHD patients.

METHODS

A randomized open-label single center study of 114 MHD patients was conducted. Forty-six patients presented negative urine culture and 41 subjects were excluded due to different reasons. The remaining 27 patients (mean age of 71.5 ± 12.2 years, 63% men), fulfilling the criteria for having asymptomatic bacteriuria, were randomly assigned to either the treatment group (13 patients) or the observational group (14 subjects). The treatment group received 7 days of antibiotic treatment given according to bacteriogram sensitivity. After 3 months of follow-up all measurements of the study were repeated. The primary end point was change in inflammatory biomarkers from baseline by the end of the study.

FINDINGS

There were no statistically significant differences in white blood cell changes (P = 0.27), ferritin (P = 0.09), C-reactive protein (P = 0.90), and interleukin-6 (P = 0.14) levels between the groups from baseline to the end of study or at the end of the study. Analyzing cross-sectional data, asymptomatic bacteriuria was found to not be a predictor of higher levels of inflammatory parameters at baseline.

DISCUSSION

Asymptomatic bacteriuria is not a modifiable risk factor for chronic inflammation in the MHD population.

Isolation Rate and Clinical Significance of Uropathogens in Positive Urine Cultures of Hemodialysis Patients

BACKGROUND

Hemodialysis (HD) patients are known to be vulnerable to infections. However, there are limited data on the urine microbiology spectrum among patients with end-stage renal disease and on the development of antimicrobial resistance of uropathogens in these patients.

MATERIALS AND METHODS

A single-center, retrospective study was conducted to assess the spectrum and antimicrobial resistance profile of microorganisms isolated in urine cultures of HD patients who were hospitalized between September 2008 and August 2015 with an admitting diagnosis of fever, sepsis, or urinary tract infection. Characteristics of patients were recorded, and associations between the aforementioned parameters were assessed with Fisher's exact test.

RESULTS

We included 75 HD patients (33 males, mean age 73.6 ± 16.6 years) with positive urine cultures. Despite urine culture positivity, the urinary tract was the confirmed source of infection in only 31 (41.3%) patients. Among the different pathogens, Escherichia coli was the predominant microorganism. Identification of E. coli as the involved uropathogen was associated neither with a growth of ≥105 CFU/ml, presence of fever, sepsis, urinary catheter use nor with higher antimicrobial resistance. E. coli growth, however, was significantly associated with polycystic kidney disease (P = 0.027). Extended antimicrobial resistance was noted in 29 (38.7%) patients but was associated neither with higher incidence of fever or sepsis nor with urinary catheter use.

CONCLUSIONS

In our series of HD patients with positive urine cultures, the isolation rates of different uropathogens do not seem to differ from the most commonly encountered ones in nondialysis patients although resistance to antimicrobials may be more frequently observed.

The Diagnostic Value of Urinalysis in Hemodialysis Patients with Fever, Sepsis or Suspected Urinary Tract Infection

INTRODUCTION

The diagnostic validity of urinalysis in asymptomatic Hemodialysis (HD) patients is low and there is limited data on the diagnostic value of urinalysis in HD patients with fever, sepsis, or suspected Urinary Tract Infection (UTI).

AIM

The aim of this study was to assess the sensitivity, specificity, positive and negative predictive value of pyuria, bacteriuria, Leukocyte Esterase (LE) and nitrite positivity in symptomatic, febrile or/and septic HD patients.

MATERIALS AND METHODS

A single-center, retrospective study was performed at New York University Lutheran Medical Center, Brooklyn, New York City, USA, in order to investigate the diagnostic validity of pyuria, bacteriuria, LE and nitrite positivity in HD patients with admitting diagnosis of fever, sepsis or UTI from September 2008 to August 2015.

RESULTS

A total of 275 HD patients were included in the study. There was significant association between pyuria of different cut-offs (>5,>10,>50 WBC/HPF) and urine culture positivity (p<0.001) and growth of ≥100,000 CFU/mL (p=0.039), but there was no association with fever or sepsis. The sensitivity and specificity of pyuria >10 WBC/HPF for positive urine culture with >100,000 CFU/mL was 86% and 35% respectively (p=0.025). Pyuria >50 WBC/HPF showed a sensitivity of 66% and a specificity of 58% (p=0.032). There was also association between bacteriuria, LE positivity and positive urine cultures but not with ≥100,000 CFU/mL.

CONCLUSION

Our study results suggest that urinalysis is not a reliable diagnostic tool in febrile and/or septic HD patients and a urine culture is needed. In such patients, physicians should also maintain a high level of clinical suspicion for other potential sources of infection, which may not be initially evident.

Successful treatment of bilateral emphysematous pyelonephritis in a uremic patient without nephrectomy

Emphysematous pyelonephritis (EPN) is a severe and complicated renal infection characterized by gas formation within the infected kidney and its surrounding tissues. Early diagnosis with a high index of suspicion and aggressive treatment are important for improving outcome. Bilateral involvement is rare, and surgical intervention is usually required because of its high mortality rate. A literature review found that EPN has rarely been noted in chronic dialysis patients, and those who show bilateral EPN have demonstrated no survival at all until now. Herein, we presented a 51-year-old diabetic uremic woman who developed right emphysematous pyelitis initially and then progressed to bilateral EPN when hospitalized. Percutaneous drainage (PCD) with simultaneous antibiotic therapy successfully eradicated her renal infection. In this study, all reported cases of EPN in chronic dialysis patients were also reviewed.