Prophylaxis against respiratory syncytial virus in young children with cystic fibrosis

Infection control in cystic fibrosis: cohorting, cross-contamination, and the respiratory therapist

Cystic fibrosis (CF) is a complex genetic disease characterized by lung infections that lead to early morbidity and death. Pathogens that commonly infect the lungs of patients with CF include Staphylococcus aureus, Haemophilus influenzae, Pseudomonas aeruginosa, and Burkholderia cepacia. Aggressively treating pulmonary infection with antibiotics has contributed to improved survival in patients with CF but has also promoted multiple-drug-resistant bacteria. Other complexities include the ability of bacteria to form biofilms, which makes them more resistant to antibiotics, and emerging pathogens in CF, of which the clinical importance is not yet clear. Increasing evidence of patient-to-patient transmission of CF pathogens led the Cystic Fibrosis Foundation to produce evidence-based infection-control recommendations, which stress 4 principles: standard precautions, transmission-based precautions, hand hygiene, and care of respiratory equipment. Respiratory therapists need to know and follow these infection-control recommendations. Cohorting patients infected with B. cepacia complex is one of several interventions successful at keeping the spread of this pathogen low, but cohorting patients who are infected/colonized with other microbes is controversial, the main argument of which is not being certain of a patient's present respiratory culture status at any given patient visit.

Special populations

Bronchiolitis is a leading cause of hospitalisation in infancy, with respiratory syncytial virus (RSV) being the most common pathogen. Younger age, especially infants younger than 3 months of age, environmental factors and genetic susceptibility, are associated with increased risk of hospitalisation. Most importantly, conditions such as prematurity, in particular if associated with chronic lung disease, congenital heart disease, lung disease such as cystic fibrosis, neuromuscular disease or impairment, or congenital or acquired immune deficiencies, are associated with increased risk of RSV hospitalisation and severe RSV lung disease. In these high risk populations, a 3- to 10-fold increase in the rate of RSV hospitalisation has been observed, justifying RSV-specific prophylaxis with palivizumab during the first, and in the populations at highest risk, the second RSV season. Studies have demonstrated a significant reduction (approximately 50%) in the rate of RSV hospitalisation in high-risk infants treated with palivizumab during the RSV season.

Palivizumab: where to from here?

Respiratory syncytial virus (RSV) is a common cause of respiratory tract infections. In severely immunosuppressed patients RSV can cause significant morbidity and mortality. The only FDA-approved drug for RSV is aerosolized ribavirin. Given the high morbidity and mortality in high-risk populations and inconsistent results with aerosolized ribavirin, new strategies for prevention and treatment of RSV are being sought. Palivizumab is an RSV-specific monoclonal antibody. A randomized, double-blind, placebo-controlled multicenter study showed significant reduction in hospitalization rates among children at high risk of RSV infection who had been given prophylactic palivizumab; these findings led to palivizumab's approval by the FDA in June 1998. Palivizumab also has a role in prevention of severe respiratory tract infections in high-risk infants. In immunocompromised patients, palivizumab has an excellent safety profile and may be beneficial in the prevention and treatment of RSV infections; however, clinical trials are needed to determine its effectiveness. In this article, we review the role of palivizumab in prevention and treatment of RSV infections in immunocompetent and immunocompromised patients.

Review of palivizumab in the prophylaxis of respiratory syncytial virus (RSV) in high-risk infants

In respiratory syncytial virus (RSV) disease the balance between the innate and adaptive immune responses determines the expression of the pathological phenotype favoring the development of acute bronchiolitis, and in certain children the development of recurrent wheezing. While humoral antibody plays a major role in protection against disease, T-cell immunity targeted to viral proteins appears to terminate viral infection. At the moment, treatment modalities for acute RSV infection do not effectively modify the course of the disease, and RSV vaccine development has shown conflicting results. To date, however, passive immunoprophylaxis with monoclonal antibodies is the only strategy that has demonstrated consistent efficacy in reducing RSV hospitalizations in high-risk children. The potential benefit of new strategies for prevention and treatment of RSV infections should be evaluated with respect to both the acute infection as well as the chronic respiratory manifestations induced by RSV.