Impact of molecular diagnostics for the detection of respiratory viruses and clinical value

Traditionally, treatment and prevention of respiratory viral disease has mainly focused on influenza virus infection. The epidemiology, impact and severity of influenza virus infection have been studied extensively and it has been shown that influenza virus infection is associated with significant mortality and morbidity every year. Despite these studies influenza, like other respiratory virus infections is often unjustly considered a relatively harmless infectious disease and treatment as not being necessary. Over the past decades, there has been growing attention towards the role of respiratory viruses, especially in immunocompromised patients. In this thesis we aimed to develop molecular diagnostic techniques feasible for use in a routine laboratory setting, and to evaluate their clinical impact. Moreover, we used these techniques to clarify the role of respiratory viruses in specific patient groups at risk. In this thesis we show that the described molecular diagnostic methods exhibit a significant advantage over the existing conventional diagnostic methods. With the use of these sensitive detection methods we show that respiratory viruses can be detected frequently and are more often involved in serious respiratory tract infection than expected previously. To determine the role of respiratory viruses in immunocompromised patients a retrospective study using the developed molecular techniques was performed in hematological cancer patients with pneumonia. With the use of these molecular diagnostics we found an increasing rate of identification from 19% to 35% compared to the conventional detection techniques. In 21% of the patients respiratory viruses were the only identified pathogen. These results led us to conduct a prospective study in which we examined the frequency and severity of respiratory virus infection in recipients who underwent autologous or allogenic stem cell transplantation. We showed an incidence of viral upper and lower respiratory tract infection of 14% with standard viral culture and with 36% with molecular diagnostics. In addition, we showed that infections with respiratory viruses occurred frequently and were associated with severe lower respiratory tract infection. The mortality associated with respiratory virus infection however was low. Finally, we have used the molecular diagnostic detection methods to evaluate the virus load and shedding during infection. Asthmatics often experience more pronounced symptoms during an upper respiratory tract infection than non asthmatics. In the described study we have studied the role of respiratory viruses, in asthmatic and non asthmatic subjects. We showed that the clearance of virus and maximal viral load were similar in both groups. However, the asthmatic subject experienced significantly more symptoms, mainly associated with the lower respiratory tract. These results indicate that ongoing virus replication is not the explanation for the severity of asthmatic symptoms and that other mechanisms, such as host response, may play a role in the development of symptoms. With future research focused on the precise pathogenicity of the various respiratory viruses and on the host's response will be needed to further address the clinical value and cost-effectiveness of molecular diagnostic techniques for the detection of respiratory viruses

Human Metapneumovirus in Adults

Human metapneumovirus (HMPV) is a relative newly described virus. It was first isolated in 2001 and currently appears to be one of the most significant and common human viral infections. Retrospective serologic studies demonstrated the presence of HMPV antibodies in humans more than 50 years earlier. Although the virus was primarily known as causative agent of respiratory tract infections in children, HMPV is an important cause of respiratory infections in adults as well. Almost all children are infected by HMPV below the age of five; the repeated infections throughout life indicate transient immunity. HMPV infections usually are mild and self-limiting, but in the frail elderly and the immunocompromised patients, the clinical course can be complicated. Since culturing the virus is relatively difficult, diagnosis is mostly based on a nucleic acid amplification test, such as reverse transcriptase polymerase chain reaction. To date, no vaccine is available and treatment is supportive. However, ongoing research shows encouraging results. The aim of this paper is to review the current literature concerning HMPV infections in adults, and discuss recent development in treatment and vaccination

Cardiac events after macrolides or fluoroquinolones in patients hospitalized for community-acquired pneumonia : Post-hoc analysis of a cluster-randomized trial

Background: Guidelines recommend macrolides and fluoroquinolones in patients hospitalized with community-acquired pneumonia (CAP), but their use has been associated with cardiac events. We quantified associations between macrolide and fluoroquinolone use and cardiac events in patients hospitalized with CAP in non-ICU wards. Methods: This was a post-hoc analysis of a cluster-randomized trial as a cohort study; including patients with a working diagnosis of CAP admitted to non-ICU wards without a cardiac event on admission. We calculated cause-specific hazard ratio's (HR's) for effects of time-dependent macrolide and fluoroquinolone exposure as compared to beta-lactam monotherapy on cardiac events, defined as new or worsening heart failure, arrhythmia, or myocardial ischemia during hospitalization. Results: Cardiac events occurred in 146 (6.9%) of 2107 patients, including heart failure (n = 101, 4.8%), arrhythmia (n = 53, 2.5%), and myocardial ischemia (n = 14, 0.7%). These occurred in 11 of 207 (5.3%), 18 of 250 (7.2%), and 31 of 277 (11.2%) patients exposed to azithromycin, clarithromycin, and erythromycin for at least one day, and in 9 of 234 (3.8%), 5 of 194 (2.6%), and 23 of 566 (4.1%) exposed to ciprofloxacin, levofloxacin, and moxifloxacin, respectively. HR's for erythromycin, compared to beta-lactam monotherapy, on any cardiac event and heart failure were 1.60 (95% CI 1.09;2.36) and 1.89 (95% CI 1.22;2.91), respectively. HR's for levofloxacin and moxifloxacin, compared to beta-lactam monotherapy, on any cardiac event were 0.40 (95% CI 0.18;0.87)and 0.56 (95% CI 0.36;0.87), respectively. Findings remained consistent after adjustment for confounders and/or in a sensitivity analysis of radiologically confirmed CAP (n = 1604, 76.1%). Conclusions: Among patients with CAP hospitalized to non-ICU wards, erythromycin use was associated with a 68% increased risk of hospital-acquired cardiac events, mainly heart failure. Levofloxacin and moxifloxacin were associated with a lower risk of heart failure. Although our study does not fully exclude confounding bias, findings remained largely unchanged in crude, adjusted, and sensitivity analyses. These findings may caution the use of erythromycin as empirical therapy in these patients. Trial registration: The original trial was retrospectively registered under ClinicalTrials.gov Identifier NCT01660204 on August 8th, 2012

Cardiac events after macrolides or fluoroquinolones in patients hospitalized for community-acquired pneumonia: post-hoc analysis of a cluster-randomized trial

Abstract Background Guidelines recommend macrolides and fluoroquinolones in patients hospitalized with community-acquired pneumonia (CAP), but their use has been associated with cardiac events. We quantified associations between macrolide and fluoroquinolone use and cardiac events in patients hospitalized with CAP in non-ICU wards. Methods This was a post-hoc analysis of a cluster-randomized trial as a cohort study; including patients with a working diagnosis of CAP admitted to non-ICU wards without a cardiac event on admission. We calculated cause-specific hazard ratio’s (HR’s) for effects of time-dependent macrolide and fluoroquinolone exposure as compared to beta-lactam monotherapy on cardiac events, defined as new or worsening heart failure, arrhythmia, or myocardial ischemia during hospitalization. Results Cardiac events occurred in 146 (6.9%) of 2107 patients, including heart failure (n = 101, 4.8%), arrhythmia (n = 53, 2.5%), and myocardial ischemia (n = 14, 0.7%). These occurred in 11 of 207 (5.3%), 18 of 250 (7.2%), and 31 of 277 (11.2%) patients exposed to azithromycin, clarithromycin, and erythromycin for at least one day, and in 9 of 234 (3.8%), 5 of 194 (2.6%), and 23 of 566 (4.1%) exposed to ciprofloxacin, levofloxacin, and moxifloxacin, respectively. HR’s for erythromycin, compared to beta-lactam monotherapy, on any cardiac event and heart failure were 1.60 (95% CI 1.09;2.36) and 1.89 (95% CI 1.22;2.91), respectively. HR’s for levofloxacin and moxifloxacin, compared to beta-lactam monotherapy, on any cardiac event were 0.40 (95% CI 0.18;0.87)and 0.56 (95% CI 0.36;0.87), respectively. Findings remained consistent after adjustment for confounders and/or in a sensitivity analysis of radiologically confirmed CAP (n = 1604, 76.1%). Conclusions Among patients with CAP hospitalized to non-ICU wards, erythromycin use was associated with a 68% increased risk of hospital-acquired cardiac events, mainly heart failure. Levofloxacin and moxifloxacin were associated with a lower risk of heart failure. Although our study does not fully exclude confounding bias, findings remained largely unchanged in crude, adjusted, and sensitivity analyses. These findings may caution the use of erythromycin as empirical therapy in these patients. Trial registration The original trial was retrospectively registered under ClinicalTrials.gov Identifier NCT01660204 on August 8th, 2012

Cardiac events after macrolides or fluoroquinolones in patients hospitalized for community-acquired pneumonia : post-hoc analysis of a cluster-randomized trial

BACKGROUND: Guidelines recommend macrolides and fluoroquinolones in patients hospitalized with community-acquired pneumonia (CAP), but their use has been associated with cardiac events. We quantified associations between macrolide and fluoroquinolone use and cardiac events in patients hospitalized with CAP in non-ICU wards. METHODS: This was a post-hoc analysis of a cluster-randomized trial as a cohort study; including patients with a working diagnosis of CAP admitted to non-ICU wards without a cardiac event on admission. We calculated cause-specific hazard ratio's (HR's) for effects of time-dependent macrolide and fluoroquinolone exposure as compared to beta-lactam monotherapy on cardiac events, defined as new or worsening heart failure, arrhythmia, or myocardial ischemia during hospitalization. RESULTS: Cardiac events occurred in 146 (6.9%) of 2107 patients, including heart failure (n = 101, 4.8%), arrhythmia (n = 53, 2.5%), and myocardial ischemia (n = 14, 0.7%). These occurred in 11 of 207 (5.3%), 18 of 250 (7.2%), and 31 of 277 (11.2%) patients exposed to azithromycin, clarithromycin, and erythromycin for at least one day, and in 9 of 234 (3.8%), 5 of 194 (2.6%), and 23 of 566 (4.1%) exposed to ciprofloxacin, levofloxacin, and moxifloxacin, respectively. HR's for erythromycin, compared to beta-lactam monotherapy, on any cardiac event and heart failure were 1.60 (95% CI 1.09;2.36) and 1.89 (95% CI 1.22;2.91), respectively. HR's for levofloxacin and moxifloxacin, compared to beta-lactam monotherapy, on any cardiac event were 0.40 (95% CI 0.18;0.87)and 0.56 (95% CI 0.36;0.87), respectively. Findings remained consistent after adjustment for confounders and/or in a sensitivity analysis of radiologically confirmed CAP (n = 1604, 76.1%). CONCLUSIONS: Among patients with CAP hospitalized to non-ICU wards, erythromycin use was associated with a 68% increased risk of hospital-acquired cardiac events, mainly heart failure. Levofloxacin and moxifloxacin were associated with a lower risk of heart failure. Although our study does not fully exclude confounding bias, findings remained largely unchanged in crude, adjusted, and sensitivity analyses. These findings may caution the use of erythromycin as empirical therapy in these patients. TRIAL REGISTRATION: The original trial was retrospectively registered under ClinicalTrials.gov Identifier NCT01660204 on August 8th, 2012

Toll-like receptor 4 is not involved in host defense against respiratory tract infection with Sendai virus

Toll-like receptors (TLR) induce innate immune responses upon stimulation by a wide variety of pathogens. TLR4 has been implicated in innate immunity against respiratory syncytial virus (RSV) by an interaction with the viral envelope fusion (F) protein. Sendai virus (mouse parainfluenza type 1) shares many features with RSV, including a structurally and functionally similar F protein. To determine the role of TLR4 in host defense against Sendai virus respiratory tract infection, TLR4 mutant and wildtype mice were intranasally infected with Sendai virus. Sendai infection resulted in an increase in viral RNA copies in lung homogenates peaking on day 4. Pulmonary viral loads, histopathology, cytokine levels and leukocyte influx were similar in TLR4 mutant and wildtype mice. In spite of the structural similarities shared by the F proteins of Sendai virus and RSV, TLR4 is not involved in host defense against respiratory tract infection with Sendai virus. (C) 2003 Published by Elsevier B.

Impact of Lung Cancer Treatment on Cognitive Functioning

The impact of oncologic treatment for (non)-small-cell lung cancer (NSCLC and SCLC, respectively) on cognition is relevant when deciding which treatment is the most preferable option, especially when curation is not possible. A systematic search of Medline and EMBASE for studies on the effect of treatment on cognition in patients with lung cancer was performed. A total of 39 longitudinal articles were included. Study populations were heterogeneous with regards to stage and treatment type. In the 7 studies concerning SCLC, the median age of patients was between 59 and 68 years. Eighty-six percent of these studies had a loss to follow-up > 10%. Six studies used objective tests to assess cognition. Objective measurements showed a negative effect on attention, memory, and fluency after treatment. Thirty-three studies concerning NSCLC were included. The mean age of patients was between 53 and 77 years. Seventy percent of these studies included patients with stage III and IV NSCLC. Over one-half of the studies had a high rate of loss to follow-up. Eighty-eight percent used objective scales to assess cognitive functioning. Subjective decline of cognitive functioning up to 11.1% was experienced, with recovery at 4 to 6 months. Objective measurement of attention showed improvement over the course of chemotherapy. In SCLC, there is a significant negative effect on attention, memory, and fluency. In NSCLC, the longer term impact of treatment on both subjective and objective cognitive functioning appears limited. Thus, there is no evidence directing treatment choice for NSCLC based on longer term cognitive deficits. Further research is needed to precisely assess the impact of lung cancer treatment on cognition

Impact of Lung Cancer Treatment on Cognitive Functioning

The impact of oncologic treatment for (non)-small-cell lung cancer (NSCLC and SCLC, respectively) on cognition is relevant when deciding which treatment is the most preferable option, especially when curation is not possible. A systematic search of Medline and EMBASE for studies on the effect of treatment on cognition in patients with lung cancer was performed. A total of 39 longitudinal articles were included. Study populations were heterogeneous with regards to stage and treatment type. In the 7 studies concerning SCLC, the median age of patients was between 59 and 68 years. Eighty-six percent of these studies had a loss to follow-up > 10%. Six studies used objective tests to assess cognition. Objective measurements showed a negative effect on attention, memory, and fluency after treatment. Thirty-three studies concerning NSCLC were included. The mean age of patients was between 53 and 77 years. Seventy percent of these studies included patients with stage III and IV NSCLC. Over one-half of the studies had a high rate of loss to follow-up. Eighty-eight percent used objective scales to assess cognitive functioning. Subjective decline of cognitive functioning up to 11.1% was experienced, with recovery at 4 to 6 months. Objective measurement of attention showed improvement over the course of chemotherapy. In SCLC, there is a significant negative effect on attention, memory, and fluency. In NSCLC, the longer term impact of treatment on both subjective and objective cognitive functioning appears limited. Thus, there is no evidence directing treatment choice for NSCLC based on longer term cognitive deficits. Further research is needed to precisely assess the impact of lung cancer treatment on cognition

IL-12 deficiency transiently improves viral clearance during the late phase of respiratory tract infection with influenza A virus in mice

T helper 1-driven immune responses have been implicated in protective immunity against viral infections. Interleukin (IL)-12 is a heterodimeric proinflammatory cytokine formed by a p35 and a p40 subunit that can induce differentiation of naïve T cells towards a T helper 1-response. To determine the role of IL-12 in respiratory tract infection with influenza, p35 gene deficient (p35-/-) and normal wild type mice were intranasally infected with influenza A virus. IL-12 p35-/- mice displayed a transiently enhanced rather than an impaired viral clearance, as indicated by a 10-fold reduction in viral loads on day 8 after infection. Although interferon-gamma levels were significantly lower in the lungs of IL-12 p35-/- mice, their cellular immune responses were not altered, as reflected by similar T cell CD69 expression and influenza-specific T cell recruitment. Our data indicate that endogenous IL-12 impairs viral clearance during the late phase of influenza A virus infection in mic

Involvement of the platelet-activating factor receptor in host defense against Streptococcus pneumoniae during postinfluenza pneumonia

Although influenza infection alone may lead to pneumonia, secondary bacterial infections are a much more common cause of pneumonia. Streptococcus pneumoniae is the most frequently isolated causative pathogen during postinfluenza pneumonia. Considering that S. pneumoniae utilizes the platelet-activating factor receptor ( PAFR) to invade the respiratory epithelium and that the PAFR is upregulated during viral infection, we here used PAFR gene-deficient ( PAFR(-/-)) mice to determine the role of this receptor during postinfluenza pneumococcal pneumonia. Viral clearance was similar in wild-type and PAFR(-/-) mice, and influenza virus was completely removed from the lungs at the time mice were inoculated with S. pneumoniae (day 14 after influenza infection). PAFR(-/-) mice displayed a significantly reduced bacterial outgrowth in their lungs, a diminished dissemination of the infection, and a prolonged survival. Pulmonary levels of IL-10 and KC were significantly lower in PAFR(-/-) mice, whereas IL-6 and TNF-alpha were only trendwise lower. These data indicate that the pneumococcus uses the PAFR leading to severe pneumonia in a host previously exposed to influenza