Pilot Study of Early Monitoring Using Urinary Screening for BK Polyomavirus as a Strategy for Prevention of BKV Nephropathy in Kidney Transplantation

An updated approach to the evaluation of the urinary sediment

Examination of the urinary sediment (U-sed) is an important non-invasive, rapid, and inexpensive tool for the diagnosis and surveillance over time of renal diseases. In this Educational Review, we describe first how to collect, prepare, and examine urine samples in order to obtain reliable results. Then, we describe the U-sed findings in isolated microscopic hematuria, glomerular diseases, acute interstitial nephritis, acute kidney injury, reactivation of the BK virus in kidney transplant recipients, and crystalluric genetic diseases.

Accurate Multiplex qPCR Detection of Epstein-Barr Virus/Cytomegalovirus/BK Virus in Kidney Transplant Patients: Pilot Study

Chronic kidney disease is a really important heath issue, and transplantation is an intervention that can greatly increase patient quality of life and survival. The aim of this study was to perform a comprehensive evaluation of the BK virus, CMV, and EBV in kidney transplant recipients (KTRs); to assess the prevalence of infections; and to test if our detection method would be feasible for use in follow-ups with KTRs. A total of 157 KTRs registered at the Clinical Hospital "Dr. C. I. Parhon", Iași, Romania, were selected using specific inclusion/exclusion criteria. We tested the blood samples from each patient for BK, EBV, and CMV using a multiplex real-time PCR (qPCR) assay and the TaqMan PCR principle. The highest prevalence was detected for BKV (11/157, 7%), followed by CMV (9/157, 5.7%) and EBV (5/157, 3.2%). By simultaneously detecting three possible nephropathic viruses and oncogenes in KTRs using multiplex real-time PCR, we aimed to optimize their monitoring and follow-up. The prevalence of the tested nephropathogenic viruses-BKV, CMV, and EBV-was comparable to that analyzed in other studies. We demonstrate that the use of qPCR for viral detection in KTRs is a robust, cost-effective method for case monitoring.

Rapid point-of-care detection of BK virus in urine by an HFman probe-based loop-mediated isothermal amplification assay and a finger-driven microfluidic chip

Background

BK virus (BKV)-associated nephropathy (BKVN) is one of the leading causes of renal dysfunction and graft loss in renal transplant recipients. Early monitoring of BKV in urine is crucial to minimize the deleterious effects caused by this virus on preservation of graft function.

Methods

We report a simple, rapid, sensitive loop-mediated isothermal amplification (LAMP) assay using an HFman probe for detecting BKV in urine. To evaluate the performance of the assay, a comparison of the HFman probe-based LAMP (HF-LAMP) assay with two qPCR assays was performed using urine samples from 132 HIV-1 infected individuals. We further evaluated the performance of HF-LAMP directly using the urine samples from these HIV-1 infected individuals and 30 kidney transplant recipients without DNA extraction. Furthermore, we combined the HF-LAMP assay with a portable finger-driven microfluidic chip for point-of-care testing (POCT).

Results

The assay has high specificity and sensitivity with a limit of detection (LOD) of 12 copies/reaction and can be completed within 30 min. When the DNA was extracted, the HF-LAMP assay showed an equivalent and potentially even higher sensitivity (93.5%) than the qPCR assays (74.2-87.1%) for 132 urine samples from HIV-1 infected individuals. The HF-LAMP assay can be applied in an extraction-free format and can be completed within 45 min using a simple heat block. Although some decreased performance was seen on urine samples from HIV-1 infected individuals, the sensitivity, specificity, and accuracy of the extraction-free BKV HF-LAMP assay were 95%, 100%, and 96.7% for 30 clinical urine samples from kidney transplant recipients, respectively.

Conclusion

The assay has high specificity and sensitivity. Combined with a portable finger-driven microfluidic chip for easy detection, this method shows great potential for POCT detection of BKV.

Frequency of pre- and post-transplant infectious agents in kidney transplant patients

Purpose: Renal transplantation is the most important and successful treatment method for renal failure. In this study, it was aimed to investigate the frequency of Cytomegalovirus (CMV), BK virus (BKV) and bacterial agents in kidney transplant recipient (KTR)s before and in the first six months after transplantation. Materials and Methods: CMV and BKV were investigated by Real-time PCR in blood samples taken from patients who underwent kidney transplantation at the Organ Transplantation Center of our faculty, one week before the transplantation and in the first, third and sixth months after transplantation. Blood, urine, respiratory tract /wound (if necessary) cultures were performed. Decoy cells were evaluated in urine cytology. Results: The mean age of KTRs was 32.60±11.71 years, 28 (62.2%) were male. Donor origins were living related donors 39 (86.7%) and cadaveric 6 (13.3%). After transplantation, BKV was detected in 11/38 (28.9%) patients, CMV was found in 25/41 (60.9%) patients, and Decoy cell positivity was detected in 11/31 (35.4%) patients. While the highest rate of Real-time PCR positivities were in the third months and sixth months for BKV and first, month for CMV and gradually decreased towards the sixth month. Escherichia coli, Klebsiella pneumoniae, Candida nonalbicans, Enterococcus faecalis were most commonly grown in urine culture. Staphylococcus hominis, Streptecoccus epidermidis, were grown in blood culture. Acinetobacter baumannii, Klebsiella pneumoniae, Aspergillus fumigatus and Candida albicans grew in the culture of respiratory tract samples. Conclusion: Bacterial infections developed early in our KTRs. While the highest Real-time PCR positivity rate was in the third and sixth months for BKV, it was the first month for CMV and gradually decreased towards the sixth month. Decoy cell positivity may be also important for diagnosis of BKV infection in KTRs.

Presence of decoy cells for 6 months on urine cytology efficiently predicts BK virus nephropathy in renal transplant recipients

OBJECTIVES

To investigate the association between duration of consecutive presence of decoy cells on urine cytology and BK virus nephropathy after kidney transplantation.

METHODS

In total, 121 kidney transplant recipients were retrospectively evaluated. The best duration of consecutive presence of decoy cells that could be used to predict BK virus nephropathy was analyzed using the area under the curve for each duration, and recipients were divided into two groups based on the best predictive performance. The effectiveness of SV40 immunostaining on urinary cytology was also analyzed.

RESULTS

In total, 2534 urine specimens as well as SV40 immunostaining in 2241 urine specimens were analyzed. Six consecutive months of decoy cell positivity had the best predictive performance for BK virus nephropathy (area under the curve = 0.832). The incidence of BK virus nephropathy in recipients with positive decoy cells for 6 months or more consecutive months (5/44) was significantly higher than in those who had positive decoy cells for less than 6 months (0/77; P = 0.005). Decoy cell positivity had a sensitivity, specificity, positive predictive value, and negative predictive value for BK virus nephropathy of 100%, 66%, 11%, and 100% respectively. SV40 immunostaining provided slightly better specificity (68%) and positive predictive value (12%).

CONCLUSIONS

The detection of decoy cells at 6 months or more on urine cytology had high predictive value for BK virus nephropathy in kidney transplant recipients. SV40 immunostaining on urine cytology added minimal diagnostic accuracy.

A case-control study to assess the role of polyomavirus in transplant complications: Where do we stand?

PURPOSE

The study's aim was to assess whether polyomavirus DNAemia screening was associated with different outcomes in patients with positive viremia compared with negative viremia.

METHODS

Case-control retrospective study of patients with polyomavirus DNAemia (viremia > 1000 copies/mL) matched 1:1 with controls. Control group consists of the patient who received a transplant immediately before or after each identified case and did have nil viremia.

FINDING

Ultimately, 120 cases of BK polyomavirus (BKPyV) were detected and matched with 130 controls. Of these, 54 were adult kidney transplant recipients (KTRs), 43 were pediatric KTRs, and 23 were undergoing hemato-oncologic therapy, of which 20 were undergoing hematopoietic stem cell transplantation. The odds ratio (OR) for overall risk of poorer outcomes in cases versus controls was 16.07 (95% CI: 5.55-46.54). The unfavorable outcome of switching the immunosuppressive drug (ISD) (14/40,35%) was no different from that of those treated with reduced ISD doses (31/71, 43.6%, P = .250). Acute rejection or graft-versus-host disease, previous transplant, and intensity of immunosuppression (4 ISDs plus induction or conditioning) were risk factors for BKPyV-DNAemia (OR: 13.96, 95% CI: 11.25-15.18, P < .001; OR: 6.14, 95% CI: 3.91-8.80, P < .001; OR: 5.53, 95% CI: 3.37-7.30, P < .001, respectively).

CONCLUSIONS

Despite viremia screening, dose reduction, and change in therapeutic protocol, patients with positive BKPyV-DNAemia present poorer outcomes and unfavorable results.

Automated Intelligent Microscopy for the Recognition of Decoy Cells in Urine Samples of Kidney Transplant Patients

BACKGROUND

BK virus (BKV)-associated nephropathy is definitely involved in allograft failure after kidney transplant. Thus, the need for an early control of viral reactivation in immunocompromised patients is well established. Determination of urinary release of decoy cells (DC) and BK viral load in plasma and urine by polymerase chain reaction (PCR) usually precedes renal biopsy. The aim of the study is to assess viral reactivation by BKV-DNA PCR and DC detection in urinary sediment using automated intelligent microscopy.

METHODS

Seventy-eight kidney transplant patients were analyzed for the presence of plasma BKV-DNA by quantitative TaqMan real-time PCR. Additionally, automated intelligent microscopy was used for urine sediment analysis, allowing to count cells with decoy feature, confirmed by phase contrast microscopic review.

RESULTS

Plasma BKV-DNA PCR was detected in 14 (17.9%) patients. DC were identified in 19 (24.3%) urine sediments by automated analyzers and confirmed by microscopic observation. Two patients were BKV-DNA-positive/DC-negative; conversely, 7 subjects were DC-positive/BKV-DNA-negative.

CONCLUSIONS

Plasma quantification of BK viral load is currently the best noninvasive method for the detection of viral reactivation. Nevertheless, automated methods to screen for the presence of DC in urine could facilitate early BK virus replication diagnosis and patient follow-up by quantitative and visual results.

Nucleic Acid Tests for BK Polyomavirus Is Critical in Renal Transplant Recipients

This study evaluates the incidence of BK polyomavirus (BKV) and prognosis of BKV infection in kidney transplant recipients (KTRs) who received transplantation in our hospital before and after regular BKV nucleic acid test (NAT) was implemented.

METHODS

The study included 74 KTRs who received a single kidney either from standard- or expanded-criteria deceased donor between March 2011 and March 2017. BKV NATs were regularly checked in 26 patients (group 1) in the first posttransplant year in accordance with current guidelines since NAT was implemented in our laboratory in 2014. We retrospectively compared 48 KTRs (group 2) who either received NAT when necessary in another laboratory or were not checked before 2014.

RESULTS

There was no significant difference in patient characteristics between groups. BKV viruria were confirmed in 8 of 26 (30.8%) group 1 patients, whereas only 2 of 48 (4.2%) BKV infections were confirmed in group 2. None of the BKV(+) KTRs in group 1 developed BK polyomavirus-associated nephropathy (BKVAN), whereas 2 BKV(+) patients (100%) of group 2 developed BKVAN, which indicates renal function deterioration and biopsy-validated nephropathy. There was no significant difference in graft survival and renal function between the 2 groups.

CONCLUSIONS

The risk of BKV infection is considerably higher in KTRs using NAT. Because there is no approval treatment, early diagnosis of BKV infection and early reduction of immunosuppression agents is critical for KTRs. Implementation of regular BKV NAT is mandatory before BKVAN and malignant neoplasms develop.

BK polyomavirus nephropathy in two kidney transplant patients with distinct diagnostic strategies for BK virus and similar clinical outcomes: two case reports

Background

BK polyomavirus-associated nephropathy is an important cause of post-transplantation renal failure. We present two cases of BK polyomavirus-associated nephropathy who were submitted to contrasting strategies of clinical follow-up to BK polyomavirus reactivation, but progressed to a similar final outcome.

Case presentation

Case 1 is a 37-year-old white man whose graft had never presented a good glomerular filtration rate function, with episodes of tacrolimus nephrotoxicity, and no urinary monitoring for BK polyomavirus; stage B BK polyomavirus-associated nephropathy was diagnosed by biopsy at 14 months post-transplant. Despite clinical treatment (dosage decrease and immunosuppressive drug change), he progressed to stage C BK polyomavirus-associated nephropathy and loss of graft function 30 months post-transplant. Case 2 is a 49-year-old mulatto man in his second renal transplantation who was submitted to cytological urinary monitoring for BK polyomavirus; he presented early, persistent, and massive urinary decoy cell shedding and concomitant tacrolimus nephrotoxicity. Even with decreasing immunosuppression, he developed BK polyomavirus-associated nephropathy 1-year post-transplant. Loss of graft function occurred 15 months post-transplant.

Conclusions

Cytological urinary monitoring was an efficient strategy for monitoring BK virus reactivation. Decoy cell shedding may be related to BK polyomavirus-associated nephropathy when extensive and persistent. The presence of associated tacrolimus nephrotoxicity may be a confounding factor for the clinical diagnosis of BK polyomavirus-associated nephropathy.