Monitoring low cytomegalovirus viremia in transplanted patients by a real-time PCR on plasma

[Cytomegalovirus. Pathological-anatomical manifestations and detection methods]

Human cytomegalovirus, a double-stranded DNA virus, is a member of the Herpesviridae family with high rates of transmission. Primary infection is often asymptomatic and leads to life-long latency. Reactivation may induce different organ manifestations, particularly in the setting of immunosuppression. Histopathologically, the virus can be detected by light microscopy. Different cell populations in different organs are transformed into"owl's eye" cells, which are pathognomonic. Immunohistochemistry and electron microscopy can be applied as complementary methods. Various PCR approaches in molecular pathology including nested PCR, capture probe ELISA-PCR and real time PCR confer HCMV tests high sensitivity and specificity. The present article discusses the methods of pathological diagnostic approaches and describes organ manifestations of HCMV.

Diagnostic strategy for hematology and oncology patients with acute respiratory failure: randomized controlled trial

RATIONALE

Respiratory events are common in hematology and oncology patients and manifest as hypoxemic acute respiratory failure (ARF) in up to half the cases. Identifying the cause of ARF is crucial. Fiberoptic bronchoscopy with bronchoalveolar lavage (FO-BAL) is an invasive test that may cause respiratory deterioration. Recent noninvasive diagnostic tests may have modified the risk/benefit ratio of FO-BAL.

OBJECTIVES

To determine whether FO-BAL in cancer patients with ARF increased the need for intubation and whether noninvasive testing alone was not inferior to noninvasive testing plus FO-BAL.

METHODS

We performed a multicenter randomized controlled trial with sample size calculations for both end points. Patients with cancer and ARF of unknown cause who were not receiving ventilatory support at intensive care unit admission were randomized to early FO-BAL plus noninvasive tests (n = 113) or noninvasive tests only (n = 106). The primary end point was the number of patients needing intubation and mechanical ventilation. The major secondary end point was the number of patients with no identified cause of ARF.

MEASUREMENTS AND MAIN RESULTS

The need for mechanical ventilation was not significantly greater in the FO-BAL group than in the noninvasive group (35.4 vs. 38.7%; P = 0.62). The proportion of patients with no diagnosis was not smaller in the noninvasive group (21.7 vs. 20.4%; difference, -1.3% [-10.4 to 7.7]).

CONCLUSIONS

FO-BAL performed in the intensive care unit did not significantly increase intubation requirements in critically ill cancer patients with ARF. Noninvasive testing alone was not inferior to noninvasive testing plus FO-BAL for identifying the cause of ARF. Clinical trial registered with www.clinicaltrials.gov (NCT00248443).

Monitoring human cytomegalovirus infection with nested PCR: comparison of positive rates in plasma and leukocytes and with quantitative PCR

BACKGROUND

Human cytomegalovirus (HCMV) infection poses a significant health threat to immunocompromised individuals. Here we performed this study to set up a highly sensitive nested PCR method applicable for detecting HCMV infection in high-risk individuals. In this work, 106 blood specimens from 66 patients with potential HCMV infection were obtained. Total DNA was extracted separately from plasma and peripheral blood leukocytes (PBL) of each sample. HCMV DNA was detected in parallel by nested PCR and quantitative real-time PCR (qRT-PCR), and the results were compared.

RESULTS

Serial dilution test revealed that the detection limit of nested PCR was 180 copies/ml. The nested PCR showed a higher positive rate than qRT-PCR (34.9% vs. 12.3%, p < 0.001). The positive rate of nested PCR based on PBL DNA was significantly higher than that based on plasma DNA (34.9% vs. 18.9%, p = 0.002). Of the 14 patients with serial samples, 11 were positive for HCMV DNA in PBL while only 7 were positive in plasma. Moreover, for each patient, nested PCR using PBL DNA also detected more positive samples than that using plasma DNA.

CONCLUSION

Combined use of nested PCR with PBL DNA is highly sensitive in defining HCMV infection. This assay is particularly useful in the case of quantification not essential.

Multi-Site PCR-based CMV viral load assessment-assays demonstrate linearity and precision, but lack numeric standardization: a report of the association for molecular pathology

Viralload (VL) assessment of cytomegalovirus (CMV) by real-time PCR is an important tool for diagnosing and monitoring CMV viremia in patients with compromised immune systems. We report results from a sample exchange organized by members of the Association for Molecular Pathology that compared PCR results from 23 laboratories; 22 such laboratories used a laboratory-developed real-time PCR assay and one laboratory used a competitive PCR assay. The samples sent to each laboratory were comprised of a dilution panel of CMV virion-derived reference materials that ranged from 0 to 500,000 copies/ml. Accuracy, linearity, and intralaboratory precision were established for the different laboratory-developed assays. Overall, PCR results were linear for each laboratory (R(2) > 0.97 in all but two). While 13 laboratories showed no significant quantitative assay bias, 10 laboratories reported VLs that were significantly different compared with expected values (bias range, -0.82 to 1.4 logs). The intralaboratory precision [mean coefficient of variance of 2% to 5% (log-scale)] suggested that changes in VLs of less than 3- to fivefold may not be significantly different. There was no significant association between laboratory-specific technical variables (PCR platform, calibrator, extraction method) and assay linearity or accuracy. These data suggested that, within each laboratory, relative VL values were linear, but additional method standardization and a CMV DNA reference standard are needed to allow laboratories to achieve comparable numeric results.

[Diagnostic strategy for acute respiratory failure in patients with haematological malignancy]

INTRODUCTION

About 15% of patients with haematological malignancy develop acute respiratory failure (ARF), necessitating admission to intensive care where their mortality is of the order of 50%.

STATE OF THE ART

The prognosis of these patients is not determined by the pathological characteristics of the malignancy but by the cause of the acute respiratory failure. In effect, the need to resort to mechanical ventilation in the presence of dysfunction of other organs dominates the prognosis. Even if the use of non-invasive ventilation in these patients has reduced the need for intubation and reduced the mortality, its prolonged use in the most severely affected patients prevents the optimal diagnostic and therapeutic management.

PERSPECTIVES

Fibreoptic bronchoscopy with broncho-alveolar lavage (BAL) is considered the cornerstone of aetiological diagnosis but its diagnostic effectiveness is poor, at best 50%, and this has led to increasing interest in high resolution CT scanning and regularly reawakens a transitory enthusiasm for surgical lung biopsy. Furthermore, in hypoxaemic patients, fibreoptic bronchoscopy with BAL may be the origin of the resort to mechanical ventilation, and thus increased mortality. The place of recently developed non-invasive tools is under evaluation. In effect, though the individual performance of diagnostic molecular techniques on sputum, blood, urine or naso- pharyngeal secretions has been established, the combination of these tools as an alternative to BAL has not yet been reported.

CONCLUSION

This review deals with acute respiratory failure in patients with haematological malignancy. It includes a review of the recent literature and considers the current controversies, in particular the risk-benefit balance of fibreoptic bronchoscopy with BAL in severely hypoxaemic patients.

Diagnostic bronchoscopy in hematology and oncology patients with acute respiratory failure: prospective multicenter data

OBJECTIVE

To describe the diagnostic yields of test strategies with and without fiberoptic bronchoscopy and bronchoalveolar lavage (FO-BAL), as well as outcomes, in cancer patients with acute respiratory failure (ARF).

DESIGN

Prospective observational study.

SETTING

Fifteen intensive care units in France.

PATIENTS

In all, 148 cancer patients, including 45 bone marrow transplant recipients (27 allogeneic, 18 autologous) with hypoxemic ARF.

INTERVENTION

None.

RESULTS

Overall, 146 causes of ARF were identified in 128 patients (97 [66.4%] pulmonary infections). The cause of ARF was identified in 50.5% of the 101 patients who underwent FO-BAL and in 66.7% of the other patients. FO-BAL was the only conclusive test in 34 (33.7%) of the 101 investigated patients. Respiratory status deterioration after FO-BAL occurred in 22 of 45 (48.9%) nonintubated patients, including 16 (35.5%) patients who required ventilatory support. Hospital mortality was 55.4% (82 deaths) overall and was not significantly different in the groups with and without FO-BAL. By multivariate analysis, mortality was affected by characteristics of the malignancy (remission, allogeneic bone marrow transplantation), cause of ARF (ARF during neutropenia recovery, cause not identified), and need for life-sustaining treatments (mechanical ventilation and vasopressors).

CONCLUSION

In critically ill cancer patients with ARF, a diagnostic strategy that does not include FO-BAL may be as effective as FO-BAL without exposing the patients to respiratory status deterioration.

Relationship between pp65 antigenemia levels and real-time quantitative DNA PCR for Human Cytomegalovirus (HCMV) management in immunocompromised patients

Background

Quantitative real-time PCR assays, which are more rapid and practical than pp65 antigenemia determination, are progressively becoming the preferred method for monitoring Human Cytomegalovirus (HCMV) reactivation. However, the relationship between HCMV DNA and antigenemia levels is still under investigation. The aim of this study was to analyse the relationship between HCMV DNA and pp65 antigenemia levels in order to identify clinically useful threshold values for the management of patients.

Methods

475 consecutive samples from 156 immunosuppressed patients were tested for HCMV by pp65 antigenemia and Real-time PCR assay.

Results

136 out of 475 consecutive samples derived from 48 patients showed evidence of HCMV infection. HCMV DNA was detected in 106 samples, pp65 antigen in 3, and both markers in 27. pp65 antigen detection was associated with higher HCMV DNA levels. The cut-off HCMV DNA level that best predicted pp65 antigenemia in this series of samples was 11,500 copies/ml, but different threshold levels could be observed for specific groups of patients. HCMV disease was observed in 5 out of 48 patients with active HCMV infection. The presence of clinical symptoms was associated with positive pp65 and with higher antigenemia levels. Higher HCMV DNA load at the onset of viral replication was correlated to the development of clinical symptoms.

Conclusion

Both pp65 antigenemia and HCMV DNA load can be useful for the prospective monitoring of immunocompromised subjects. Specific cut-off levels capable of triggering preemptive antiviral treatment should be determined in accordance to the type of test used and the characteristics of patients and prospectively validated.

Pulmonary complications of haematopoietic cell transplantation in children

Paediatric haematopoietic cell transplantation has experienced significant advances in the last few decades. However, pulmonary complications are an important limitation to the efficacy of this intervention, contributing to post-transplantation morbidity and mortality. Such complications persist even in experienced centres and occur in adult and paediatric recipients. This review identifies the paediatric pulmonary complications that are commonly seen following haematopoietic cell transplantation and addresses both infectious and non-infectious aetiologies and their clinical manifestations, evaluation, and potential therapy. Ultimately, improvement in outcomes will require attention to immunosuppression as well as traditional diagnostic procedures and treatment. This article aims to review the current state of pulmonary complications post-transplantation, to examine the impact of our recent advances and changes in treatment, and to identify potential future therapies and hypothesise what role these might have on long-term survival.

Diagnostic strategy in cancer patients with acute respiratory failure

OBJECTIVE

Nearly 15% of cancer patients experience acute respiratory failure (ARF) requiring admission to the intensive care unit, where their mortality is about 50%. This review focuses on ARF in cancer patients. The most recent literature is reviewed, and emphasis is placed on current controversies, most notably the risk/benefit ratio of fiberoptic bronchoscopy and BAL in patients with severe hypoxemia.

BACKGROUND

Fiberoptic bronchoscopy with bronchoalveolar lavage (BAL) is the cornerstone of the causal diagnosis. However, the low diagnostic yield of about 50%, related to the widespread use of broad-spectrum antimicrobial therapy in cancer patients, has generated interest in high-resolution computed tomography (HRCT) and primary surgical lung biopsy. In patients with hypoxemia, bronchoscopy and BAL may trigger a need for invasive mechanical ventilation, thus considerably decreasing the chances of survival.

DISCUSSION

The place for recently developed, effective, noninvasive diagnostic tools (tests on sputum, blood, urine, and nasopharyngeal aspirates) needs to be determined. The prognosis is not markedly influenced by cancer characteristics; it is determined chiefly by the cause of ARF, need for mechanical ventilation, and presence of other organ failures. Although noninvasive ventilation reduces the need for endotracheal intubation and diminishes mortality rate, its prolonged use in patients with severe disease may preclude optimal diagnostic and therapeutic management. The appropriateness of switching to endotracheal mechanical ventilation in patients who fail noninvasive ventilation warrants evaluation.

CONCLUSION

This review discusses risks and benefits from invasive and non invasive diagnostic and therapeutic strategies in critically ill cancer patients with acute respiratory failure. Avenues for research are also suggested in order to improve survival in these very high risk patients.

Recommendations for Outpatient Monitoring of Kidney Transplant Recipients

Clinical and laboratory outpatient monitoring is an important tool in the prevention and management of complications associated with kidney transplantation and immunosuppressive therapy. In the absence of standard protocols for outpatient surveillance of kidney transplant recipients, recommendations for frequency and type of monitoring are determined by the likelihood of problems that are unique to the individual transplant recipient and the particular posttransplantation period. In addition, it is imperative to maintain the transplant recipient's overall health by screening for conditions or diseases that can be linked to prior renal disease, immunosuppressive therapies, and general health maintenance.

Early Detection of Plasma Cytomegalovirus DNA by Real-Time PCR after Allogeneic Hematopoietic Stem Cell Transplantation

Cytomegalovirus (CMV) infection is an important cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Therefore, preemptive ganciclovir therapy based on early detection of CMV reactivation is widely used to prevent CMV disease. Real-time polymerase chain reaction (PCR) has been widely used for monitoring CMV reactivation as well as the antigenemia assay that detects CMV structural phosphoprotein with a molecular weight of 65,000 (pp65). We developed a real-time PCR assay system for CMV based on a double-stranded DNA-specific dye, SYBR Green I, and quantified DNA, which was extracted automatically from plasma. This real-time PCR assay and the pp65 antigenemia assay were compared in parallel with 357 blood samples obtained from 64 patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT). Real-time PCR assay results correlated with those of the pp65 antigenemia assay (p < 0.0001). It is noteworthy that the detection of CMV DNA by PCR preceded the first positive antigenemia by 14 days. In this study, 10 of 64 patients developed CMV disease. The antigenemia assay detected CMV reactivation earlier than the development of CMV disease only in four of 10 patients. In contrast, our real-time PCR detected CMV-DNA before the development of CMV diseases in eight of 10 patients. The real-time PCR with SYBR Green I as a detection signal is simple and readily performed, and may be a useful system for early detection of CMV reactivation after allo-HSCT.