ASSOCIATION OF CYTOMEGALOVIRUS DNA CONCENTRATION IN EPITHELIAL LINING FLUID AND SYMPTOMATIC CYTOMEGALOVIRUS INFECTION IN LUNG TRANSPLANT RECIPIENTS

Detection of herpes viruses by multiplex and real-time polymerase chain reaction in bronchoalveolar lavage fluid of patients with acute lung injury or acute respiratory distress syndrome

BACKGROUND

Human herpes viruses (HHVs) are important pathogens in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Rapid and efficient diagnostic tools are needed to detect HHVs in the lung in ALI/ARDS patients.

OBJECTIVES

This study aimed to evaluate the usefulness of multiplex and real-time polymerase chain reaction (PCR) analysis of bronchoalveolar lavage fluid (BALF) for detecting HHV reactivation in ALI/ARDS patients.

METHODS

Between August 2008 and July 2012, eighty-seven BALF samples were obtained from ALI/ARDS patients with unknown etiology and analyzed for HHVs. The types of HHVs in the BALF samples were determined using qualitative multiplex PCR followed by quantitative real-time PCR.

RESULTS

Multiplex PCR identified herpes simplex virus type 1 (HSV-1) (n = 11), Epstein-Barr virus (EBV) (n = 16), cytomegalovirus (CMV) (n = 21), HHV type 6 (HHV-6) (n = 2), and HHV-7 (n = 1) genomic DNA in 35 (40%) of the BALF samples, including 14 (16%) samples containing 2 or 3 HHV types. CMV and EBV reactivation was rare in immunocompetent patients, whereas reactivation of HSV-1 was predominantly observed in intubated patients regardless of their immune status. Overall, HHVs were almost exclusively found in patients with immunosuppression or endotracheal intubation. Real-time PCR detected 0.95-1.59 × 10(6) copies of viral DNA/μg human genome DNA, and HSV-1 (n = 4), CMV (n = 9), and HHV-6 (n = 1) were identified as potentially pathogenic agents.

CONCLUSIONS

The implementation of multiplex and real-time PCR of BALF was feasible in ALI/ARDS patients, which allowed efficient detection and quantification of HHV DNA.

Point: is the era of viral culture over in the clinical microbiology laboratory?

Conventional tube culture systems have long been the mainstay in clinical virology for the growth and identification of viruses from clinical specimens. Innovations such as centrifugation-enhanced shell vial and multiwell plate cultures and the use of genetically engineered and mixed cell lines, coupled with faster detection of viral replication, have allowed for reasonable turnaround times for even some of the most slowly growing clinically important human viruses. However, molecular methods, in particular, the PCR, have usurped the role of viral culture in many laboratories, limiting the use of this traditional method of virus detection or replacing it altogether. Advances and improvements in molecular technology over time have also resulted in newer generations of more rapid and accurate molecular assays for the detection, quantification, and genetic characterization of viruses. For this point-counterpoint, we have asked two individuals, Richard L. Hodinka of the Children's Hospital of Philadelphia, a clinical virologist whose laboratory has completely eliminated viral culture in favor of molecular methods, and Laurent Kaiser, head of the Virology Laboratory at the University of Geneva Hospital, who continues to be a strong advocate of viral culture, to discuss the relevance of viral culture in the molecular age.

Detection of parvovirus B19 in the lower respiratory tract

BACKGROUND

Human parvovirus B19 infection generally displays a self-limiting course followed by viral clearance; although, in some cases, persistent infection may occur. Few cases of severe pulmonary disease following primary infection in both immunocompetent and immunocompromised patients were reported.

OBJECTIVES

To investigate the prevalence and clinical impact of parvovirus B19 in the lower respiratory tract.

STUDY DESIGN

The prevalence of parvovirus B19-DNA was evaluated by Real-Time PCR in 264 bronchoalveolar lavages (BAL) from 189 adult patients over a full-year period and related to demographic characteristics, underlying pathologies, immune status, admission to intensive care unit, mortality within 28 days, and discharge diagnosis.

RESULTS

Parvovirus B19-DNA was detected in 7/189 (3.7%) patients, without significant association to demographic characteristics, immune status, transplant versus non-transplant status, admission to intensive care unit, presence of haematological conditions. In two lung transplant recipients surveillance specimens were positive to B19. Four of the remaining five patients presented respiratory insufficiency. A significant association to mortality was found, as 3/7 (42.9%) positive patients died within 28 days. No patient presented serological evidence of recent or acute infection and viremia.

CONCLUSIONS

Parvovirus B19 may be detected at low frequency in BAL specimens from patients with different pathological backgrounds. This finding could be due to chronic infection with virus persistence in the lower respiratory tract, also in the absence of symptoms unequivocally attributable to B19. The high rate of mortality warrants the need for further studies to evaluate the opportunity to consider parvovirus B19 in the diagnostic work-up of lower respiratory tract infections.

Pulmonary infections in transplantation pathology

CONTEXT

Pulmonary infections are common and often life-threatening in solid organ and stem cell transplant recipients. Understanding their pathology is critical to making improvements in care and survival as well as in surgical techniques, immunosuppression management, prophylaxis, and treatment. Pulmonary infections are particularly common and serious in the susceptible population of lung transplant recipients.

OBJECTIVE

To summarize recent updates in the field for opportunistic infections and some common pathogens, and to consider the role of the diagnostic pulmonary histopathologist as well as advances in molecular diagnosis.

DATA SOURCES

This work is based on a selected review of the relevant medical and scientific literature, with emphasis on lung transplantation experience gained during 2 decades of practice.

CONCLUSIONS

Pulmonary infections in transplant recipients present a diagnostic challenge and are a continuing source of mortality and morbidity despite improvement in prophylaxis and treatment. Accurate diagnosis requires multidisciplinary input from clinicians, radiologists, and pathology disciplines as well as complementary molecular methods.

Quantitative detection of herpes simplex virus DNA in the lower respiratory tract

Quantitation of herpes simplex virus (HSV) DNA in bronchoalveolar lavage specimens could indicate an infectious role in the lower respiratory tract. The aim of this study was to compare quantitative HSV DNA results from adult bronchoalveolar lavage specimens to clinical outcome. Quantitative real-time PCR assays targeting HSV and other herpes viruses were performed on adult bronchoalveolar lavage specimens obtained from a largely immunocompromised population during a 1-year period. The results were compared to patient characteristics and outcome. HSV DNA was detected in 11 (19%) of 57 bronchoalveolar lavage specimens with a mean viral level of 5.6 log genome equivalents/ml (range, 2.9-8.1 log). A threshold of HSV DNA levels equal or higher than 5.0 log (n = 7) was associated with mortality within 28 days following hospital admission (odds ratio [OR], 6.8; 95% confidence interval [CI], 1.2-39.2). A threshold level of 5.5 log was associated with mortality within 28 days of sampling (OR 8.5; 95% CI 1.2-62.1), only after excluding patients receiving specific antiviral medication. Patients with HSV DNA levels equal or higher than 7.5 log had severe respiratory failure. Viral pneumonia was histologically proven in one patient with 8.0 log at autopsy. No patient with HSV DNA levels below 5.5 log (n = 5) or DNA levels higher than 5.0 log of cytomegalovirus (CMV) (n = 3), Epstein-Barr virus (EBV) (n = 9), varicella-zoster virus (VZV) (n = 1), or human herpesvirus 6 (HHV-6) (n = 0) died within 28 days of hospital admission. We conclude that quantitative detection of HSV DNA in bronchoalveolar lavage fluid is a potential diagnostic tool for detection of relevant viral infection of the lower respiratory tract.

Relationship between cytomegalovirus DNA load in epithelial lining fluid and plasma of lung transplant recipients and analysis of coinfection with Epstein-Barr virus and human herpesvirus 6 in the lung compartment

Cytomegalovirus (CMV) is a significant cause of morbidity and mortality in lung transplant recipients (LTRs). The aim of the present study was to elucidate the relationship between the CMV DNA load in the lung compartment and that in plasma. For CMV load determination, the level of CMV DNA in plasma and bronchoalveolar lavage (BAL) samples was measured in a total of 97 paired BAL and plasma samples obtained from 25 LTRs. The original virus concentration in the epithelial lining fluid (ELF) was calculated from the BAL samples by correcting for dilution using the urea dilution method. In addition, the load of Epstein-Barr virus (EBV) and that of human herpesvirus 6 (HHV-6) DNA also were determined in BAL samples, recalculated for their concentrations in the ELF, and compared with the CMV DNA load. CMV DNA was found more frequently and at significantly higher levels in the lung compartment than in plasma (P<0.001, Wilcoxon test), and the CMV load in the ELF was associated with symptomatic CMV disease. EBV and HHV-6 were detected in 43.6% and 21.7% of the ELF samples, respectively. A statistically significant association was found between the CMV and EBV DNA loads in the ELF (P<0.001; Spearman's rho=0.651). Thus, in LTRs, determination of the CMV DNA load in the lung compartment may be advantageous compared to monitoring only viremia. The significant relationship between EBV and CMV DNA loads in the ELF of LTRs and its clinical impact require further investigation.

Emergence of Multiple Cytomegalovirus Strains in Blood and Lung of Lung Transplant Recipients

BACKGROUND

Cytomegalovirus (CMV) is a major pathogen in lung transplant recipients (LTRs). The emergence of different CMV strains in lung and blood after transplantation has not yet been analyzed.

METHODS

In total, 75 serum and 91 broncheoalveolar lavage (BAL) samples obtained from 25 LTRs in the follow-up after transplantation were tested for the presence of different CMV strains. The gB, gN, and gO genes of the CMV isolates were analyzed by subtype-specific PCR, restriction fragment length polymorphism (RFLP), sequencing, and phylogenetic analysis.

RESULTS

Mixed CMV-strain populations were detected after cessation of antiviral prophylaxis in up to 80% and 90% of the patients' BAL and serum, respectively, and this was independent of the CMV serostatus of donor and recipient. In five patients, the same single CMV strain was consistently detectable over at least 1 year in lung and blood, although in two of these cases donor and recipient had both been CMV-seropositive. Most CMV strains were distributed in the lung and blood compartment. Symptomatic CMV infection within the first year after transplantation was observed only in patients with mixed CMV-strain populations (P<0.05).

CONCLUSION

Most LTRs harbor more than one CMV strain in their lung and blood compartment after cessation of prophylaxis, but the CMV strain distribution within and between the compartments varies between individuals and is not associated with the donor/recipient serostatus. The data further show that compartmentalization of CMV strains in lung versus blood seems to be a rare event and that the presence of mixed CMV-strain infections within the first year after transplantation may be disadvantageous for LTRs.

Quantification of adenovirus in the lower respiratory tract of patients without clinical adenovirus-related respiratory disease

Adenovirus in bronchoalveolar lavage fluid samples from 50 patients without adenovirus-related illness was quantified. In 49 patients, adenovirus was found (median load, 3.3 x 10(3) copies/microg of DNA). The adenovirus load was inversely related to lymphocyte count (Pearson correlation coefficient r = -0.311; P = .03) and was significantly greater in immunosuppressed patients than in immunocompetent patients (5.1 x 10(3) vs. 2.0 x 10(3) copies/microg of DNA; P = .028).