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Respiratory syncytial virus: How, why and what to do.

J Infect. 2013 Oct 27;

Authors: Rodriguez R, Ramilo O

Abstract
Bronchiolitis is the leading cause of hospitalization of infants and young children worldwide. Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis in infants. Studies conducted using molecular diagnostic assays confirmed that RSV accounts for over 50% of bronchiolitis in young children requiring hospitalization. Those studies demonstrate that it is common to identify RSV in association with a second viral agent but it is yet unclear whether the simultaneous detection of two or even three viruses is associated with increased disease severity. Despite extensive efforts, a vaccine for prevention of RSV infection is not yet available. Palivizumab a humanized monoclonal antibody directed against the F protein of RSV is the only agent licensed to prevent severe RSV disease in high-risk children. Among the new antivirals being developed for treatment of RSV infections, an RNA-interference based agent has demonstrated promising results for treatment of lung transplant recipients with acute RSV infection.

PMID: 24171820 [PubMed - as supplied by publisher]

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Related Articles

Staphylococcus aureus accounts for 2-5 % of the etiologies of community-acquired pneumonia. These infections occur mainly in elderly patients with comorbidity, after a respiratory viral infection. S. aureus could also be responsible for necrotizing pneumonia, which occurs in young subjects, also after flu. Necrotizing pneumonia are associated with the production of a particular staphylococcal toxin called Panton-Valentine leukocidin, responsible for pulmonary focal necrosis, occurrence haemoptysis, leucopenia, and death.

In Europe, these strains are still predominantly sensitive to anti-staphylococcal penicillin, which must be used at high dosage intravenously in combination with an antibiotic that reduces toxin production such as clindamycin, and intravenous immunoglobulin in severe cases. The mortality rate is estimated at 50 %. In addition, S. aureus is one of the pathogens involved in early respiratory infections in cystic fibrosis patients, in whom methicillin resistance plays an important prognostic role. However, the involvement of S. aureus in COPD exacerbations is rare. Finally, S. aureus represents 20 to 30 % of cases of hospital-acquired pneumonia, including ventilator-associated pneumonia. In these cases, methicillin-resistance is common, may play a prognostic role and requires the use of glycopeptides or linezolid.

The place of new anti-staphylococcal antibiotics such as new generation cephalosporins or tigecyclin remains to be defined.

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Overuse of antibiotics for upper respiratory tract infections (URIs) and acute bronchitis is a persistent and vexing problem. In the U.S., more than half of all patients with upper respiratory tract infections and acute bronchitis are treated with antibiotics annually, despite the fact that most cases are viral in etiology and are not responsive to antibiotics. Interventions aiming to reduce unnecessary antibiotic prescribing have had mixed results, and successes have been modest. The objective of this evaluation is to use mixed methods to understand why a multi-level intervention to reduce antibiotic prescribing for acute bronchitis among primary care providers resulted in measurable improvement in only one third of participating clinicians.

METHODS: Clinician perspectives on print-based and electronic intervention strategies, and antibiotic prescribing more generally, were elicited through structured telephone surveys at high and low performing sites after the first year of intervention at the Geisinger Health System in Pennsylvania (n = 29).

RESULTS: Compared with a survey on antibiotic use conducted 10 years earlier, clinicians demonstrated greater awareness of antibiotic resistance and how it is impacted by individual prescribing decisions---including their own. However, persistent perceived barriers to reducing prescribing included patient expectations, time pressure, and diagnostic uncertainty, and these factors were reported as differentially undermining specific intervention components' effectiveness. An exam room poster depicting a diagnostic algorithm was the most popular strategy.

CONCLUSIONS: Future efforts to reduce antibiotic prescribing should address multi-level barriers identified by clinicians and tailor strategies to differences at individual clinician and group practice levels, focusing in particular on changing how patients and providers make decisions together about antibiotic use.

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Winter-seasonal epidemics of pneumococcal disease provide an opportunity to understand the drivers of incidence. We sought to determine whether seasonality of invasive pneumococcal disease is caused by increased nasopharyngeal transmission of the bacteria or increased susceptibility to invasive infections driven by co-circulating winter respiratory viruses.

METHODS. We analyzed pneumococcal carriage and invasive disease data collected from children <7 years in the Navajo/White Mountain Apache populations between 1996 and 2012. Regression models were used to quantify seasonal variations in carriage prevalence, carriage density, and disease incidence. We also fit a multivariate model to determine the contribution of carriage prevalence and respiratory syncytial virus (RSV) activity to pneumococcal disease incidence while controlling for shared seasonal factors.

RESULTS. The seasonal patterns of invasive pneumococcal disease epidemics varied significantly by clinical presentation: bacteremic pneumococcal pneumonia incidence peaked in late-winter while invasive non-pneumonia pneumococcal incidence peaked in autumn. Pneumococcal carriage prevalence and density also varied seasonally, with peak prevalence occurring in late-autumn. In a multivariate model, RSV activity was associated with significant increases in bacteremic pneumonia cases (attributable percent: 15.5%, 95%CI: 1.8-26.1%) but was not associated with invasive non-pneumonia (8.0%, 95%CI: -4.8-19.3%). In contrast, seasonal variations in carriage prevalence were associated with significant increases in invasive non-pneumonia infections (31.4%, 95%CI: 8.8-51.4) but not with bacteremic pneumonia.

CONCLUSIONS. The seasonality of invasive pneumococcal pneumonia could be due to increased susceptibility to invasive infection triggered by viral pathogens, while seasonality of other invasive pneumococcal infections might be primarily driven by increased nasopharyngeal transmission of the bacteria.

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