Comparison of cytomegalovirus viral load measure by real-time PCR with pp65 antigenemia for the diagnosis of cytomegalovirus disease in solid organ transplant patients

Cytomegalovirus (CMV) infection is the most frequent complication in solid organ transplant recipients. Currently, the antigenemia assay is widely used to detect this infection, although its success is being questioned to a great extent nowadays. The aim of our study is to compare a quantitative real time PCR to measure CMV DNA to the antigenemia assay, for the diagnosis to CMV disease. For our research, we prospectively processed 1198 samples (plasma and peripheral blood leukocytes [PBMC]), which belonged to 158 transplant recipients. In every sample the detection of the pp65 antigen in PBMC was carried out, as well as the quantification of CMV DNA by PCR (Light Cycler, LC-PCR). For this process, FRET probes, which detect a 254-bp fragment from the CMV gB gene, were used. The dynamic range of the LC-PCR was 500 to 5.10(7) copies/mL plasma and from 62 to 6.10(6) copies/10(6) PBMC. Twenty-three episodes of cytomegalovirus (CMV) disease occurred in 22 out of 158 patients and PCR displayed levels of sensitivity and specificity of 100% and 67%, respectively. The antigenemia assay obtained values of 91% and 57%. We established a cutoff value of 10(3) copies/mL plasma and 315 copies/10(6) cells. According to these cutoff values, PCR showed levels of sensitivity, specificity, VPN and VPP of 95.6%, 81.6%, 99%, and 53% respectively. Moreover, the LC-PCR assay anticipated the antigenemia assay in 10 patients out of 22 who developed CMV disease and the appearance of any clinical symptoms in 12 out of 22 patients. In conclusion, we believe that the quantification of CMV DNA by LC-PCR is a superior assay to pp65 antigenemia test regarding the early diagnosis of CMV disease in solid organ transplant recipients.     

Monitoring of human cytomegalovirus infections in heart transplant recipients by pp65 antigenemia

BACKGROUND: Rapid diagnostic techniques offer the opportunity of early diagnosis of human cytomegalovirus (CMV) infection in immunocompromized patients at risk of developing CMV disease and syndrome. The use of CMV pp65 antigenemia as a predictor of CMV syndrome and disease in heart transplant recipient after induction therapy was studied retrospectively. METHODS: One hundred and nineteen consecutive heart transplant recipients treated with induction therapy who survived more then 14 d were monitored for CMV infection. Ninety-four recipients were seropositive for CMV. Twenty-five recipients were seronegative for CMV and received grafts from seropositive donors. Pre-emptive therapy was used in seropositive patients when CMV pp65 antigenemia was greater than 50 antigen-positive cells per 2 x 10(5) peripheral blood leukocytes (PBL); prophylactic therapy was done only in seronegative recipient matched with seropositive donor. RESULTS: High-level CMV pp65 antigenemia (50 antigen-positive cells 2 x 10(5) PBL) occurred in 34% (41 of 119) of patients at a median of 44 d following transplantation. In seropositive recipients, 16% (15 of 94) of patients developed CMV invasive disease or syndrome, and in seronegative recipients 20% (5 of 25) of patients developed CMV disease or syndrome. Sixty-six per cent (62 of 94) of CMV seropositive patients were identified as not requiring pre-emptive therapy. In seropositive and seronegative recipients, the sensibility and negative predictive value of the cut-off level of 50 antigen positive cell for CMV disease and syndrome was 100%. The specificity was 79% and positive predictive value was 49%. CONCLUSION: Because of the excellent sensibility and negative predictive value of the cut-off level of 50 antigen positive cell per 2 x 10(5) PBL, application of pre-emptive therapy guided by high level of CMV pp65 antigenemia in the context of induction therapy allow to omit antiviral therapy in many at risk patients. In the context of pre-emptive and prophylactic therapy, the cut-off level of 50 antigen positive cell do not allow to predict with accuracy the development of CMV disease or syndrome.     

A prospective study comparing cytomegalovirus antigenemia, DNAemia and RNAemia tests in guiding pre-emptive therapy in thoracic organ transplant recipients

We evaluated the usefulness of DNAemia and mRNAemia tests in guiding the pre-emptive therapy against cytomegalovirus (CMV) infections in thoracic organ transplant recipients using antigenemia test as the reference. Seven lung (LTR) and 14 heart (HTR) transplant recipients were prospectively monitored for CMV by antigenemia, DNAemia (Cobas Amplicor PCR Monitor) and pp67-mRNAemia (NASBA) tests. However, only the antigenemia test guided pre-emptive therapy with cut-off levels of >or=2 and >or=5-10 pp65-positive leukocytes/50 000 leukocytes in the LTRs and HTRs, respectively. CMV DNAemia was detected in 26/28 (93%) and RNAemia in 17/28 (61%) of the CMV antigenemias requiring antiviral therapy (P = 0.01). Optimal DNAemia levels (sensitivity/specificity) estimated from receiver-operating characteristic curve to achieve maximal sum of sensitivity and specificity were 400 (75.9/92.7%), 850 (91.3/91.3%) and 1250 (100/91.5%) copies/ml for the antigenemia of 2, 5 and 10 pp65-positive leukocytes, respectively. The sensitivities of nucleic acid sequence-based amplification (NASBA) were 25.9%, 43.5% and 56.3% in detecting the same cut-off levels of antigenemia. In thoracic organ transplant recipients, the Cobas PCR assay is comparable with the antigenemia test in guiding pre-emptive therapy against CMV infections when threshold levels of over 5 pp65-antigen-positive leukocytes are used as the reference. In contrast, the low sensitivity of NASBA limits its usefulness in the guidance of pre-emptive therapy.     

Comparison between RFLP-PCR and antigenemia for pp65 antigen for diagnosis of cytomegalovirus disease after kidney transplantation

Cytomegalovirus (CMV) infection is the single most frequent infectious complication in renal transplant recipients. The purpose of this study was to analyze the diagnostic efficacy of PCR-RFLP compared to antigenemia for CMV disease (CMVD) in kidney transplant recipients. From November 2001 to February 2002, 19 renal adult transplant recipients were followed with weekly measurements of CMV pp65 antigen to monitor the activity of CMV from the week 4 to 12 posttransplantation. Only 4 (21.1%) patients did not develop viremia during the first 12 posttransplantation weeks. Active infection was observed in 15 patients (78.9%): asymptomatic viremia in 6 (31.6%) and CMVD in 9 (47%). All patients who developed CMVD showed positivity in both methods during the observation period. The number of positive cells ranged from 11 to 292 cells in patients with CMVD and one to eight cells among those with asymptomatic viremia. Both methods revealed 100% sensitivity for CMVD diagnosis. The specificity was 60% for antigenemia and 70% for PCR, with positive predictive values of 60% and 75%, respectively.     

A prospective multicenter observational study of cell‐mediated immunity as a predictor for cytomegalovirus infection in kidney transplant recipients

T cell immunity is essential for the control of cytomegalovirus (CMV) infection after transplantation. We evaluated a CMV‐specific peptide‐based enzyme‐linked immunosorbent spot (ELISPOT) assay to determine whether assay results could predict subsequent CMV events. Adult kidney transplant recipients at 43 centers underwent ELISPOT testing to enumerate interferon gamma (IFN‐γ) binding spot‐forming units (sfu) after stimulation of cells with an overlapping peptide pool of CMV phosphoprotein 65 (pp65) and immediate early‐1 (IE‐1) protein at the end of antiviral prophylaxis (EOP) and various time points thereafter. The primary outcome was a CMV event in the first posttransplant year. In 583 kidney transplant recipients (260 seropositive donor [D+]/seronegative recipient [R?] and 277 R+), CMV events occurred in 44 of 368 eligible patients (11.8%) at a median of 227 days (range 92‐360) posttransplant. A cutoff value of >40 sfu/2.5 × 10⁵ cells for either IE‐1 or pp65 was derived as a threshold for positivity, with a negative predictive value of >97% for CMV events. CMV events were significantly lower in assay positive vs assay negative patients (3.0% vs 19.5%, P < .0001 for pp65). Time to CMV event post‐EOP was significantly greater in those with sfu >40 at EOP (P < .0001). In this large, multicenter trial of kidney transplant recipients, we show that an assessment of CMV‐specific immunity using a novel ELISPOT assay is able to predict protection from CMV infection.     

Detection of human cytomegalovirus antigenaemia: a rapid diagnostic technique for predicting cytomegalovirus infection/pneumonitis in lung and heart transplant recipients.

BACKGROUND--New rapid diagnostic techniques offer the opportunity of early diagnosis of human cytomegalovirus (CMV) infection in immunocompromised patients at risk of developing CMV disease. The use of human CMV antigenaemia as a predictor of clinical CMV infection and disease in lung and heart transplant recipients was studied prospectively. METHODS--Twenty three heart and nine lung transplant recipients who survived 40 days were observed by standard CMV surveillance with serological testing, culture, and by sequential testing for CMV antigenaemia. CMV antigenaemia testing is a rapid and quantifiable technique in which a viral lower matrix protein is detected in cytospin preparations of peripheral blood polymorphonuclear leucocytes (PMNLs) by immunofluorescent staining. RESULTS--Eleven patients developed CMV infection and five developed CMV disease (four pneumonitis, one duodenitis). These clinical events occurred at a median of 65 days following transplantation. CMV antigenaemia occurred in 17 patients at a median of 35 days following transplantation. Detection of CMV antigenaemia had a sensitivity of 100%, a specificity of 93.7%, and a positive predictive value of 94.1% for CMV related illness. CMV antigenaemia was positive at a significant interval before the clinical event. High levels of CMV antigenaemia (> 50 CMV antigen positive cells/2 x 10(5) PMNLs) occurred in 11 patients and five of these developed disease. CMV antigenaemia of > 50 CMV antigen positive cells/2 x 10(5) PMNLs had a positive predictive value of 45.5% for disease but a negative predictive value of 100%. Patients with disease had higher levels of antigenaemia than those without disease. CONCLUSIONS--CMV antigenaemia is a rapid diagnostic technique which can identify patients likely to develop CMV disease, potentially allowing early treatment.     

Evaluation of a new method for early detection of active cytomegalovirus infections. A study in kidney transplant recipients

Abstract Early detection of active cytomegalovirus (CMV) infection after organ transplantation is necessary to start effective antiviral treatment. In the present study, blood specimens of kidney transplant recipients ( n = 38) were monitored for the expression of CMV immediate early (IE) and late (L) mRNA using nucleic acid sequence-based amplification (NASBA). Results were compared with virus isolation, pp65 antigenemia and serology. In patients developing active CMV infection, pp65 antigen and L mRNA were detected simultaneously. At the same time, positive cell culture results could be reported to the clinic. CMV was detected significantly earlier with IE NASBA than with the other assays. However, the specificity of IE NASBA is lower than that of antigenemia, late NASBA and cell culture. Early detection of IE mRNA is especially useful for patients at high risk of developing symptomatic CMV infection in order that early, adequate antiviral therapy may be started. Late NASBA can be used to monitor further development of CMV infection, comparable to antigenemia.     

Cytomegalovirus infection in organ-transplant recipients: diagnostic value of pp65 antigen test, qualitative polymerase chain reaction (PCR) and quantitative Taqman PCR

BACKGROUND: The human cytomegalovirus (CMV) is a major cause of morbidity and mortality in transplant patients. In this study, we compared the diagnostic value of pp65 antigen test, qualitative nested polymerase chain reaction (PCR), and quantitative Taqman PCR in predicting the clinical outcome of CMV infection. METHODS: A total of 169 samples derived from 59 organ-transplant recipients (kidney n= 46, liver n= 11, kidney and pancreas n= 2) were analyzed. Peripheral blood leukocytes (PBL) were isolated using dextran gradient centrifugation, and 2 x 10 cells were analyzed for pp65 antigen by immunofluorescence. A crude DNA extract obtained from the same number of cells was used for qualitative nested PCR and quantitative Taqman PCR analysis. RESULTS.: The correlation coefficient of pp65 antigen test and Taqman PCR was R= 0.699 (P = 0.001). With cut-off values for pp65 antigen test set at greater than 10 positive nuclei per 2 x 10 PBL, sensitivity was 91%, and positive predictive value (PPV) was 70%. When the corresponding cut-off value for Taqman PCR was applied (>125000 genome copies per 2 x 10 PBL), a sensitivity of 83% and a PPV of 68% were found. Both assays allowed for the monitoring of successful antiviral therapy. Although qualitative nested PCR was highly sensitive (95%), it was less useful in predicting CMV disease (PPV 47%) and in therapy control. CONCLUSION: Our data show that pp65 antigen test and Taqman PCR are almost equivalent in the monitoring of CMV infection and disease when identical cell numbers are used for both assays.     

实时定量PCR方法监测肾移植患者血浆巨细胞病毒DNA载量及其意义

目的 采用实时定量荧光PCR方法检测巨细胞病毒(CMV)DNA拷贝数,探讨病毒载量变化在诊断CMV活动性感染中的意义和指导抗病毒治疗中的作用.方法 对40例采用预排空治疗策略预防CMV病的肾移植受者同时进行CMV抗原血症(pp65)分析和病毒载量监测并进行随访,观察CMV-DNA载量和pp65在判断肾移植受者CMV活动性感染和指导抗病毒治疗中的价值.结果 264份样本中逆转录-聚合酶链反应(RT-PCR)检测57份阳性(21.59%),病毒载量水平2.648×101～5.273×105copy/ml;抗原血症分析检测48份阳性(18.18%),抗原指数1～18/5万WBC;Cohen,s-Kappa检验结果表明两种检测方法一致性良好(Kappa=0.762).25例(62.5%)患者PCR方法检测阳性,19例(47.5%)抗原血症分析阳性.病毒载量首次出现阳性时间为(13.22±14.78)d,pp65首次出现时间为(26.72±20.61)d,差异有统计学意义(P＜0.05).40例患者中4例出现CMV病,发病时间133～179 d,3例发病前pp65和CMV-DNA均为阳性,1例仅CMV-DNA阳性.结论 血浆CMV载量检测与抗原血症分析一致性良好,而敏感性较高,更准确反映肾移植术后CMV活动性,更适合用于肾移植术后预防CMV感染的预排空治疗策略.     

Therapeutic implication of quantitative pp65 antigen assay in living renal transplant in a high seroendemic population

Various methods have been used to diagnose cytomegalovirus (CMV) infection/disease; however, pp65 antigenemia assay has emerged as a good marker for CMV disease in a high seroendemic population. We studied the role of quantitative pp65 antigen assay in live related renal transplant recipients in a high seroendemic population. Between November 1998 and May 2003, a total of 350 blood samples from 250 symptomatic patients were tested by quantitative pp65 antigen assay; 14% of the patients tested positive. There were 5 (14%) low-positive and 30 (86%) high-positive patients. All high-positive patients had CMV disease. The response to antiviral therapy monitored by the assay was dramatic, and one low-positive patient responded to reduction in immunosuppression. In conclusion, pp65 antigen assay is a good test for diagnosing CMV disease and monitoring response to antiviral therapy in a high seroendemic population.     

Clinical evaluation of a new recombinant antigen-based cytomegalovirus immunoglobulin M immunoassay in liver transplant recipients

BACKGROUND: Human cytomegalovirus (CMV) is a significant cause of morbidity and mortality among transplant recipients. Monitoring transplant recipients by CMV IgM serology has been questioned by several studies due to the reported insensitivity of serologic tests relative to antigen detection methods. METHODS: In this retrospective study, we have evaluated the performance of the new recombinant antigen-based Abbott AxSYM CMV IgM assay and compared it with CMV culture technique in a cohort of 40 liver transplant recipients who did not receive antiviral prophylaxis. RESULTS: The sensitivity, specificity, and positive and negative predictive values for detection of CMV disease by the AxSYM CMV IgM assay were 90.0%, 60.0%, 69.2%, and 85.7%, respectively, and by culture the values were 100%, 55.0%, 69.0%, and 100%, respectively. Detection of CMV IgM occurred before or at the time of CMV disease in only R+ recipients. CONCLUSION: Although this assay is a sensitive test for CMV-specific IgM, detection of CMV IgM preceded detection of virus by culture in patients only when the liver transplant recipient was CMV immune before transplantation (R+).     

Clinical usefulness of plasma quantitative polymerase chain reaction assay: diagnosis of cytomegalovirus infection in kidney transplant recipients

Background

Preemptive therapy is used to prevent cytomegalovirus (CMV) disease in transplant recipients. The CMV antigenemia assay, which has been commonly used as a predictive marker for preemptive therapy, requires intensive labor and immediate processing. We compared the cutoff value of plasma CMV polymerase chain reaction (PCR) with CMV antigenemia in kidney transplant recipients.

Methods

We compared two diagnostic methods for CMV infection in kidney transplant recipients: quantitative PCR (qPCR) versus antigenemia. We evaluated the optimal cutoff value of plasma CMV qPCR by using receiver-operating characteristic curves for specific antigenemia values. All kidney transplant recipients from January 2004 to January 2005 were enrolled and followed with CMV antigenemia and plasma CMV qPCR.

Results

The analyses were performed on 899 samples collected from 111 patients in the early posttransplant period, matching 84.1% of patients for the results of CMV antigenemia and plasma CMV qPCR. For patients with symptomatic CMV infection and disease, who showed ≥25 positive cells in the antigenemia assay, the cutoff value for qPCR was 17.8 copies/μL with a sensitivity of 97.1%, a specificity of 89.1%, and a positive predictive value of 26.6%.

Conclusions

Diagnostic assays for CMV such as CMV antigenemia and quantitative plasma PCR, showed similar diagnostic values. They are the methods of choice for the diagnosis and monitoring of active CMV infection after kidney transplantation. However, because of the relatively low positive predictive value of qPCR, this test may lead to unnecessary preemptive treatment in kidney transplant recipients.     

Utility of cytomegalovirus viral load in renal transplant patients in Argentina

BACKGROUND: Cytomegalovirus (CMV) is the most prevalent viral disease in solid organ transplantation. Detection of CMV DNA in peripheral blood mononuclear cells (PBMC) by polymerase chain reaction (PCR) frequently occurs in renal allograft recipients, yielding false positive results in seropositive patients free of CMV disease. We evaluated the clinical utility of a quantitative PCR-enzyme-linked immunosorbent assay (ELISA) for identifying patients with CMV disease. METHODS: Three hundred and fifty samples from 65 consecutive renal transplant recipients were studied. DNA was extracted from PBMC weekly up to the day of discharge and after any further admission. Samples were tested by a qualitative PCR method, and all positive samples were further studied by a quantitative PCR-ELISA method. The quantitative PCR-ELISA method used an internal standard (IS) that contained the primer sequences used in the qualitative CMV PCR. Detection and quantification was performed in 96-well plates coated with IS or CMV specific probes. RESULTS: Forty-one of 65 patients (63.1%) showed positive results by the qualitative PCR, but only 8 of these patients were diagnosed with CMV disease. Positive samples were re-analyzed by the quantitative assay. The 8 patients with CMV disease had a mean CMV viral load of 1,438+/-687 viral copies (VC)/10(6) PBMC, and the 33 without CMV disease had a mean value of 219.6+/-117.2 VC/10(6) PBMC (P<0.01). None of the 33 patients without CMV disease had viral loads higher than 500 VC/10(6) PBMC. Using 500 VC/10(6) PBMC as a cut-off value for CMV disease, the quantitative PCR showed a sensitivity and specificity of 100% compare to clinical diagnosis. CONCLUSION: CMV viral load may be useful in the diagnosis of CMV disease in renal transplant patients.     

A prospective study of the natural course of cytomegalovirus infection and disease in renal allograft recipients

BACKGROUND: Cytomegalovirus (CMV) infection is the single most frequent infectious complication in renal transplant recipients. Because no CMV-prophylaxis is given and ganciclovir is used only as deferred therapy for CMV disease at our center, we have been able to study the natural course of CMV infections. The aim was to assess risk factors for CMV infection and disease and thus identify subgroups of patients likely to benefit from CMV prophylaxis or preemptive therapy. METHODS: Between October 1994 and July 1997, 477 consecutive renal transplant recipients (397 first transplants and 80 retransplants) were included in the study. The patients were followed prospectively for 3 months with serial measurements of CMV pp65 antigen for monitoring activity of CMV infections. RESULTS: The incidence of CMV infections in first transplants was 68% in D+R- and D+/-R+ serostatus groups, whereas the incidence of CMV disease was higher in D+R- (56%) than in D+/-R+ (20%, P<0.001). No difference in severity of CMV disease in D+R- and D+/-R+ was seen except for an increased incidence of hepatitis in primary infections. One of 14 deaths could be associated with CMV disease in a seropositive recipient. Cox regression analysis showed that rejection (RR 2.5, P<0.01) and serostatus group D+R- (RR 3.9, P<0.001) were significant risk factors for development of CMV disease. The maximum CMV pp65 antigen count had significant correlation to disease only in CMV seropositive recipients, P<0.001. Conclusion. Renal transplant recipients can safely be given deferred ganciclovir therapy for CMV disease if they are intensively monitored for CMV infection. Patients with primary CMV infection (D+R-), CMV infected patients undergoing anti-rejection therapy and R+ patients with high CMV pp65 counts seem to have a particular potential for benefit from preemptive anti-CMV-therapy.     

Deferred versus prophylactic therapy with gancyclovir for cytomegalovirus in allograft liver transplantation

OBJECTIVE: The aim of this study was to assess the efficacy of deferred versus prophylactic therapy with gancyclovir to prevent cytomegalovirus (CMV) infection or disease in liver transplantation recipients, and to alter the timing of infection or the incidences of acute rejection, chronic rejection, or death. METHODS: We retrospectively studied 89 consecutive liver transplant recipients with a minimum of 1 year follow-up. CMV early antigen detection (pp65) was performed weekly for the first 2 months and thereafter monthly for an additional 10 months. Forty-one recipients were administered prophylactic treatment and (48 recipients) deferred therapy for positive antigenemia. RESULTS: During the first year after transplantation, CMV infection or disease developed in 61% or 12.2% of those treated with prophylactic therapy and 54.1% or 31.3% of those treated with deferred therapy (P = 0.51 or P = 0.032, respectively). The mean time to CMV disease in the prophylactic group was 161 +/- 33 days compared with 82 +/- 27 days for the deferred therapy arm (P < 0.001). Subgroup analysis based on CMV serological status also showed prophylactic treatment significantly diminished CMV disease in the CMV IgG antibody negative group. No patients died in the prophylactic group, and one died in the deferred group (P = 0.54). The incidence of acute rejection episodes was 34% in the prophylactic and 46% in the deferred group (P = 0.26). Chronic rejection was observed in two recipients in the prophylactic group versus one recipient in the deferred arm (P = 0.35). CONCLUSION: Compared with deferred therapy prophylactic therapy with gancyclovir decreased CMV disease and delayed the onset of CMV disease after liver transplantation.     

Cytomegalovirus disease latent and active infection rates during the first trimester after kidney transplantation

Cytomegalovirus (CMV) infection is the single most frequent infectious complication in renal transplant recipients. The aim of this study was to determine the incidence of latent and active infections with CMV during the first 3 months after kidney transplantation. From January 2000 to December 2001, 203 consecutive adult renal transplant recipients underwent weekly measurements of pp65 CMV antigen from the 4th to the 12th posttransplantation week. Latent infection (seropositivity) was found in 92% of the population. Primary infection occurred in 4.9% (10 of 203), among whom 66% were previously seronegative patients. Among the primary infection patients, 70% (7 of 10) developed severe disease. The overall incidence of viremia was 69.5%, being more frequent among cadaver recipients (79% vs 59%; P =.02). The overall incidence of CMV disease was 38.4% (78 of 203) with 24.6% classified as severe disease requiring antiviral therapy. In conclusion, our population showed a high prevalence of latent infection with viremia. Not all patients developed clinical disease. Most subjects experienced a mild spectrum of symptoms, probably due to the prospective search for active infection during the major risk period after kidney transplantation.     

Fatal case of Aspergillus coinfection in a renal transplant recipient suffering from cytomegalovirus pneumonitis

Cytomegalovirus (CMV) disease is common in postrenal transplant recipients, and may predispose the patients to secondary bacterial or fungal infections. However, simultaneous coinfection is rare and often makes diagnosis difficult. We report a case of CMV pneumonitis in a renal transplant recipient presenting with elevated CMV pp65 antigen level and abnormal chest radiograph. Despite potent and broad-spectrum antimicrobial therapy, his condition deteriorated rapidly - he soon went into respiratory failure, septic shock and died several days later. Transbronchial biopsy and bronchoalveolar lavage obtained before the patient's death showed evidence of invasive pulmonary aspergillosis with concomitant CMV pneumonitis. High index of suspicion and early and empirical initiation of antifungal therapy may be necessary for successful management of fulminant pneumonia in solid organ transplant recipients.     

Real-time PCR assay compared with antigenemia assay for detecting cytomegalovirus infection in kidney transplant recipients

Human cytomegalovirus (CMV) infection is a major cause of morbidity and mortality among kidney transplant recipients. The CMVpp65 antigenemia assay has been used for preemptive therapy. Real-time polymerase chain reaction (PCR) technology for CMV DNA quantification in blood has demonstrated a good correlation with the currently employed CMV antigenemia assay. In this study, 90 renal transplant recipients were prospectively enrolled from July 2004 and May 2005. Monitoring of CMV infection was routinely performed with CMV antigenemia and real-time PCR assays. Real-time plasma PCR and CMV antigenemia assays were assessed on 797 samples. CMV antigenemia correlated with a positive CMV PCR (chi(2) = 78.05; P < .0001). Not only the positive rate but also the number of positive cells correlated with the number of PCR DNA copies (F = 26.07, r(2) = .25, P < .0001). To define an optimal cutoff value of CMV DNA load to initiate treatment in kidney transplant patients, we considered a CMV antigenemia titer of >50 positive cells per 400,000 leukocytes as the gold standard in our previous study. The optimal cutoff value for the quantitative real-time PCR assay was predicted to be 86 copies/microL. Thus, we observed that CMV real-time PCR assay would not completely replace antigenemia assay in kidney transplant recipients, but can be used complementarily to screen antigenemia and monitor preemptive therapy.     

Efficacy and limitations of preemptive therapy against cytomegalovirus infections in heart transplant patients

OBJECTIVES: Cytomegalovirus (CMV) disease often represents a serious complication that promotes opportunistic infections in heart transplant recipients. In this study we evaluated the impact of preemptive gancylovir therapy, guided by pp65 antigenemia on the morbidity associated with viral reactivation. PATIENTS AND METHODS: We have performed a CMV infection surveillance program since March 1999, with antigenemia pp65 determinations weekly for the first 2 months biweekly in the third months, and monthly to the sixth month. Patients with pp65 antigenemia value >/= 10 positive cells per 2 x 10(5) polymorphonuclear cells (PMN) were treated with intravenous gancyclovir followed by 1 month of oral gancyclovir. RESULTS: Among the 107 patients who underwent the virological monitoring, 80 were pp65 antigenemia-positive with preemptive therapy administered in 48 cases. Five patients displayed symptomatic CMV disease (4.7% vs 18% rate in the period of 1988 to 1998 before the introduction of virologic monitoring; P <.01). We observed only one case of gancyclovir-resistant pneumonia which was successfully treated with foscarnet. CMV recurrence in 10 patients required a second cycle of gancyclovir treatment. Our experience included 13 opportunistic infections (12.7%) with 11 antigenemia-positive. CONCLUSIONS: Preemptive therapy drastically reduces the incidence of CMV disease and the associated morbidity. Compared to universal prophylaxis, this approach may avoid unnecessary pharmacologic treatment in more than 50% of transplant recipients. Indeed, preemptive therapy does not fully prevent CMV disease, because it may manifest at the first antigenemia determination, and furthermore may select gancyclovir-resistant strains.