Impact of pretransplant CMV-specific T-cell immune response in the control of CMV infection after solid organ transplantation: a prospective cohort study

INTRODUCTION

Although solid organ transplant (SOT) recipients with pretransplant serology for cytomegalovirus (CMV-R+) are considered at intermediate risk for CMV infection post transplantation, CMV infection remains a major cause of morbidity in this population. We prospectively characterized whether having pretransplant CMV-specific cellular immunity is independently associated with controlling infection after transplantation in R + SOT recipients.

METHODS

A prospective cohort of consecutive R + SOT recipients that received pre-emptive treatment for CMV infection was monitored after transplantation and variables were recorded during the follow-up. The cytomegalovirus-specific T-cell immune response was characterized by intracellular cytokine staining and viral loads determined using real-time PCR.

RESULTS

One hundred and thirty-five R + SOT recipients were included (67 kidney, 64 liver, four liver-kidney). Only one-third of the patients (42; 31.85%) had CMV-specific T-cell immunity (CD8⁺CD69⁺INF-γ⁺ T cells >0.25%) before transplantation. Patients with negative pretransplant immunity had more CMV infection (49, 52.7% vs. 15, 35.7%; p 0.07) and received more antiviral therapy than those with immunity (32, 34.4% vs. 6, 14.3%, p 0.016). Having CMV specific immunity was an independent factor for protection from developing viraemia ≥2000 IU/mL (OR 0.276, 95% CI 0.105-0.725, p < 0.01) and lower administration of treatment (OR 0.398, 95% CI 0.175-0.905, p 0.028). Only patients with no pretransplant CMV-specific T-cell response were diagnosed with CMV-disease (8, 8.6% vs. 0, 0%, p 0.05).

DISCUSSION

Our results show that having a pretransplant CMV specific T-cell response may be associated with a lower rate of CMV viraemia and less antiviral treatment after transplantation; however, more prospective studies are needed to confirm these findings.

Administration of taurolidine-citrate lock solution for prevention of central venous catheter infection in adult neutropenic haematological patients: a randomised, double-blinded, placebo-controlled trial (TAURCAT)

Background

Catheter-related bloodstream infection (CRBSI) is one of the most frequent complications in patients with cancer who have central venous catheters (CVCs) implanted and is associated with substantial morbidity and mortality. Taurolidine is a non-antibiotic agent with broad-spectrum antimicrobial activity, which has been used as a lock solution to prevent CRBSI in some settings. However, little is known about its usefulness in high-risk adult neutropenic patients with cancer. This prospective randomised clinical trial aims to test the hypothesis that taurolidine-citrate lock solution is more effective than placebo for preventing catheter infection in neutropenic haematological patients.

Methods

This study is a prospective, multicentre, randomised, double-blinded, parallel, superiority, placebo-controlled trial. Patients with haematological cancer who are expected to develop prolonged neutropenia (> 7 days) and who have a non-tunnelled CVC implanted will be randomised to receive prophylactic taurolidine-citrate-heparin solution using a lock technique (study group) or heparin alone (placebo group). The primary endpoint will be bacterial colonisation of the CVC hubs. The secondary endpoints will be the incidence of CRBSI, CVC removal, adverse events, and 30-day case-fatality rate.

Discussion

The lock technique is a preventive strategy that inhibits bacterial colonisation in the catheter hubs, which is the initial step of endoluminal catheter colonisation and the development of infection. Taurolidine is a nontoxic agent that does not develop antibiotic resistance because it acts as an antiseptic rather than an antibiotic. Taurolidine has shown controversial results in the few trials conducted in cancer patients. These studies have important limitations due to the lack of data on adult and/or high-risk neutropenic patients, the type of catheters studied (tunnelled or ports), and the lack of information regarding the intervention (e.g. dwelling of the solution, time, and periodicity of the lock technique). If our hypothesis is proven, the study could provide important solid evidence on the potential usefulness of this preventive procedure in a population at high risk of CRBSI, in whom this complication may significantly impair patient outcome.

Trial registration

ISRCTN, ISRCTN47102251. Registered on 9 September 2015.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2647-y) contains supplementary material, which is available to authorized users.

Use of antibodies neutralizing epithelial cell infection to diagnose patients at risk for CMV Disease after transplantation

OBJECTIVES

Although a CMV-specific T-cell response is associated with reduced risk for infection after transplantation, some patients still develop CMV disease. Thus, the characterization of additional parameters of the CMV-specific immune response that correlate with the control of CMV infection and disease and their use in defining thresholds that can be applied to clinical practice is of interest.

METHODS

In a cohort of high risk solid organ transplant recipients we characterized CMV-specific T-cell responses using intracellular cytokine staining upon stimulation with pp65 and IE-1 peptides, and levels of CMV-specific antibodies neutralizing infection in fibroblast (MRC-5) and epithelial (ARPE-19) cells using microneutralization assays.

RESULTS

Although patients with a positive (≥0.25%CD8(+)CD69(+)IFN-γ+) T-cell response were 6.4 fold more protected (OR 6.4, 95% CI 1.6-25.3; p < 0.001) from CMV infection than patients without a response, 2 (4.2%) patients developed disease. We defined a cut-off titer for epithelial cell neutralizing antibodies of ≥480 that correlated with disease protection. Thus, patients with a CMV-specific T-cell response and titers ≥480 were 14.2 fold more protected from CMV infection (OR 14.2, 95% CI 5-40.2; p < 0.001) and had no episodes of CMV disease.

CONCLUSIONS

Our results indicate that antibodies neutralizing epithelial cell infection may have an important role in long-term protection. Quantification of antibodies neutralizing epithelial cells, in addition to the T-cell response, may be useful for identifying patients with lower risk for CMV disease.

Lack of association between genotypes and haematogenous seeding infections in a large cohort of patients with methicillin-resistant Staphylococcus aureus bacteraemia from 21 Spanish hospitals

There is increasing concern regarding the association between certain methicillin-resistant Staphylococcus aureus (MRSA) genotypes and poor clinical outcome. To assess this issue, a large cohort of 579 subjects with MRSA bacteraemia was prospectively followed from June 2008 to December 2009, in 21 hospitals in Spain. Epidemiology, clinical data, therapy, and outcome were recorded. All MRSA strains were analysed in a central laboratory. Presence of a haematogenous seeding infection was the dependent variable in an adjusted logistic regression model. Of the 579 patients included in the study, 84 (15%) had haematogenous seeding infections. Microdilution vancomycin median MIC (IQR) was 0.73 (0.38-3) mg/L. Most MRSA isolates (n = 371; 67%) belonged to Clonal Complex 5 (CC5) and carried an SCCmec element type IV and agr type 2. Isolates belonging to ST8-agr1-SCCmecIV, ST22-agr1-SCCmecIV and ST228-agr2-SCCmecI--a single locus variant of ST5--accounted for 8%, 9% and 9% of the isolates, respectively. After adjusting by clinical variables, any of the clones was associated with increased risk of haematogenous seeding infections. Higher vancomycin MIC was not identified as an independent risk factor, either. In contrast, persistent bacteraemia (OR 4.2; 2.3-7.8) and non-nosocomial acquisition (3.0; 1.7-5.6) were associated with increased risk.

Determination, validation and standardization of a CMV DNA cut-off value in plasma for preemptive treatment of CMV infection in solid organ transplant recipients at lower risk for CMV infection

BACKGROUND

Valganciclovir preemptive therapy guided by the viral load is the current strategy recommended for preventing CMV disease in CMV-seropositive Solid Organ Transplant Recipients (SOTR) at lower risk for developing CMV infection. However, universal viral load cut-off has not been established for initiating therapy.

OBJECTIVES

Our goal was to define and validate a standardized cut-off determined in plasma by real-time PCR assay for initiating preemptive therapy in this population.

STUDY DESIGN

A prospective cohort study of consecutive cases of CMV-seropositive SOTR was carried out. The cut-off value was determined in a derivation cohort and was validated in the validation cohort. Viral loads were determined using the Quant CMV LightCycler 2.0 real-time PCR System (Roche Applied Science) and results were standardized using the WHO International Standard for human CMV.

RESULTS

A viral load of 3983 IU/ml (2600 copies/ml) was established as the optimal cut-off for initiating preemptive therapy in a cohort of 141 patients with 982 tests and validated in a cohort of 252 recipients with a total of 2022 test. This cut-off had a 99.6% NPV indicating that the great majority of patients at lower risk will not develop CMV disease without specific antiviral therapy. The high sensitivity and specificity (89.9% and 88.9%, respectively) and the relatively small numbers of patients with CMV disease confirm that real-time PCR was optimal.

CONCLUSIONS

We have established a cut-off viral load for starting preemptive therapy for CMV-seropositive SOT recipients. Our results emphasized the importance of a mandatory follow-up protocol for CMV-seropositive patients receiving preemptive treatment.