Association of respiratory viral infections with pulmonary deterioration in patients with cystic fibrosis

Early intervention and prevention of lung disease in cystic fibrosis: a European consensus

In patients with cystic fibrosis (CF), early intervention and prevention of lung disease is of paramount importance. Principles to achieve this aim include early diagnosis of CF, regular monitoring of the clinical status, various hygienic measures to prevent infection and cross-infection, early use of antibiotic courses in patients with recurrent or continuous bacterial colonisation and appropriate use of chest physiotherapy.

The common cold: a review of the literature

Respiratory viral infections, also known as the common cold, are the most common infections in humans. Despite their benign nature, they are a major cause of morbidity and mortality on a worldwide basis. Several viruses have been associated with such illness, of which rhinovirus is the most common. Symptom production is a combination of viral cytopathic effect and the activation of inflammatory pathways. Therefore, antiviral treatment alone may not be able to prevent these events. The optimal use of such agents also requires earlier initiation; therefore, it is important to develop accurate and rapid diagnostic techniques for respiratory viruses. Before any reliable and effective treatment is available, symptomatic therapies may remain the only possible choice of management.

Infection control in cystic fibrosis

Over the past 20 years there has been a greater interest in infection control in cystic fibrosis (CF) as patient-to-patient transmission of pathogens has been increasingly demonstrated in this unique patient population. The CF Foundation sponsored a consensus conference to craft recommendations for infection control practices for CF care providers. This review provides a summary of the literature addressing infection control in CF. Burkholderia cepacia complex, Pseudomonas aeruginosa, and Staphylococcus aureus have all been shown to spread between patients with CF. Standard precautions, transmission-based precautions including contact and droplet precautions, appropriate hand hygiene for health care workers, patients, and their families, and care of respiratory tract equipment to prevent the transmission of infectious agents serve as the foundations of infection control and prevent the acquisition of potential pathogens by patients with CF. The respiratory secretions of all CF patients potentially harbor clinically and epidemiologically important microorganisms, even if they have not yet been detected in cultures from the respiratory tract. CF patients should be educated to contain their secretions and maintain a distance of >3 ft from other CF patients to avoid the transmission of potential pathogens, even if culture results are unavailable or negative. To prevent the acquisition of pathogens from respiratory therapy equipment used in health care settings as well as in the home, such equipment should be cleaned and disinfected. It will be critical to measure the dissemination, implementation, and potential impact of these guidelines to monitor changes in practice and reduction in infections.

Respiratory virus infections in cystic fibrosis

Respiratory virus infections have pronounced and long-lasting effects on patients with cystic fibrosis (CF), resulting in significant declines in FVC, FEV(1) and Shwachman score, significantly increasing both the frequency and duration of hospitalisation. Deleterious effects on patients with CF have been reported for most viruses studied but the effects of respiratory syncytial virus and influenza appear the greatest. There is circumstantial evidence that respiratory virus infections may facilitate bacterial infections, particularly Pseudomonas aeruginosa.

Immunogenicity of a new purified fusion protein vaccine to respiratory syncytial virus: a multi-center trial in children with cystic fibrosis

A third generation, purified fusion protein (PFP-3) vaccine was developed to prevent severe respiratory syncytial virus (RSV) disease in high-risk groups. A phase II, multi-center, adjuvant-controlled trial was performed in RSV seropositive children with cystic fibrosis (CF); 151 received the adjuvant-control and 143 received the vaccine. Details of the vaccine-induced immune response are presented. At enrollment, RSV-specific, serum antibodies were comparable between both groups. A highly sensitive and specific serum antibody vaccine profile was established for the PFP-3 vaccine. At post-vaccination and end-of-study, RSV-specific, neutralizing antibody (Nt Ab) and binding antibody (Bd Ab) to the fusion (F) protein were significantly higher in PFP-3 vaccinees. After 28 days post-vaccination, Nt Ab and Bd Ab to F protein titers declined slowly at rates of 0.23 and 0.37 log2 per month, respectively. The PFP-3 vaccine-induced a robust immune response that lasted throughout the RSV season.

Impaired innate host defense causes susceptibility to respiratory virus infections in cystic fibrosis

Viral infection is the primary cause of respiratory morbidity in cystic fibrosis (CF) infants. Here, we identify that host factors allow increased virus replication and cytokine production, providing a mechanism for understanding the severity of virus disease in CF. Increased virus is due to lack of nitric oxide synthase 2 (NOS2) and 2', 5' oligoadenylate synthetase (OAS) 1 induction in response to virus or IFNgamma. This can be attributed to impairment of activation of signal transducer and activator of transcription (STAT)1, a fundamental component to antiviral defense. NO donor or NOS2 overexpression provides protection from virus infection in CF, suggesting that NO is sufficient for antiviral host defense in the human airway and is one strategy for antiviral therapy in CF children.

Infection control recommendations for patients with cystic fibrosis: microbiology, important pathogens, and infection control practices to prevent patient-to-patient transmission

Infection Control Recommendations for Patients With Cystic Fibrosis: Microbiology, Important Pathogens, and Infection Control Practices to Prevent Patient-to-Patient Transmissionupdates, expands, and replaces the consensus statement,Microbiology and Infectious Disease in Cystic Fibrosispublished in 1994. This consensus document presents background data and evidence-based recommendations for practices that are intended to decrease the risk of transmission of respiratory pathogens among CF patients from contaminated respiratory therapy equipment or the contaminated environment and thereby reduce the burden of respiratory illness. Included are recommendations applicable in the acute care hospital, ambulatory, home care, and selected non-healthcare settings. The target audience includes all healthcare workers who provide care to CF patients. Antimicrobial management is beyond the scope of this document.

Impact of respiratory viral infections on cystic fibrosis

The life expectancy for patients with cystic fibrosis has improved remarkably over the last 20 years. Progressive deterioration of pulmonary function continues despite the aggressive use of antimicrobials. The absence of fever, neutrophilia, and systemic symptoms suggest that during pulmonary exacerbations other non-bacterial factors may have played a part. Some have suggested respiratory viruses as main suspects. So far, few data have illustrated the relationship of respiratory viruses and cystic fibrosis. By gaining further knowledge of this relationship, one may change future clinical practice and boost the survival of these patients.

Selected populations at increased risk from respiratory syncytial virus infection

Respiratory syncytial virus (RSV) is the principal cause of bronchiolitis and pneumonia in infants and young children worldwide. Deficits in cellular immunity appear to promote severe RSV disease in children with malignancies, those undergoing chemotherapy and bone marrow transplant recipients. Respiratory syncytial virus infection appears to exacerbate pulmonary symptoms of cystic fibrosis. In such patients RSV disease may result in a prolonged hospital course, which is often complicated by the need for mechanical ventilation. Retrospective analyses of hospital admissions for RSV bronchiolitis among Native American and Alaskan Native children younger than 1 year of age have demonstrated rates of 62 per 1000 or higher, compared with the national average of 34 per 1000. Among these ethnic groups, specific host factors as well as environmental factors appear to contribute to these comparatively high rates of hospitalization for RSV infection. Respiratory syncytial virus has the potential to cause disease in all age groups. A 3-year observational study found that individuals who lived in a community setting, or who cared for young children on a consistent basis, experienced acute respiratory infections more commonly than those living independently or whose interaction with children was limited.

Effects of inhaled gentamicin prophylaxis on acquisition of Pseudomonas aeruginosa in children with cystic fibrosis: a pilot study

Inhaled antibiotics are an established treatment for chronic Pseudomonas aeruginosa (PA) infection in patients with cystic fibrosis (CF). However, inhaled antibiotics might also have prophylactic potential to delay acquisition of PA in early stages of the disease. From 1986-1999, all CF patients at this center who experienced defined risk situations for acquisition of PA (28 patients) received inhaled gentamicin (80 mg BID for those < 12 months; 120 mg BID for those > 12 months) for a minimum of 3 years. Twelve patients had repeated risk situations and continued this prophylaxis without interruption during the entire study period (group 1). In the remaining 16 patients, inhaled antibiotics were discontinued at various times for a variety of reasons (group 2). None of the patients in group 1, but 7 in group 2, became chronically infected with PA (P = 0.01). Lung function and chest X-ray scores were significantly worse in those 7 infected patients, when compared to the noninfected ones in both groups. This suggests that long-term-prophylaxis with inhaled gentamicin can effectively delay acquisition of PA and decrease disease progression in children with CF.

Replication-competent or attenuated, nonpropagating vesicular stomatitis viruses expressing respiratory syncytial virus (RSV) antigens protect mice against RSV challenge

Foreign glycoproteins expressed in recombinant vesicular stomatitis virus (VSV) can elicit specific and protective immunity in the mouse model. We have previously demonstrated the expression of respiratory syncytial virus (RSV) G (attachment) and F (fusion) glycoprotein genes in recombinant VSV. In this study, we demonstrate the expression of RSV F and G glycoproteins in attenuated, nonpropagating VSVs which lack the VSV G gene (VSVDeltaG) and the incorporation of these RSV proteins into recombinant virions. We also show that intranasal vaccination of mice with nondefective VSV recombinants expressing RSV G (VSV-RSV G) or RSV F (VSV-RSV F) elicited RSV-specific antibodies in serum (by enzyme-linked immunosorbent assay [ELISA]) as well as neutralizing antibodies to RSV and afford complete protection against RSV challenge. In contrast, VSVDeltaG-RSV F induced detectable serum antibodies to RSV by ELISA, but no detectable neutralizing antibodies, yet it still protected from RSV challenge. VSVDeltaG-RSV G failed to induce any detectable serum (by ELISA) or neutralizing antibodies and failed to protect from RSV challenge. The attenuated, nonpropagating VSVDeltaG-RSV F is a particularly attractive candidate for a live attenuated recombinant RSV vaccine.

Cost-effectiveness of influenza vaccination in high-risk children in Argentina

OBJECTIVES

our study aimed to evaluate the cost-effectiveness of influenza vaccination in high-risk children in Argentina.

METHODS

a decision analysis model was performed, using data from published and unpublished sources, to compare two strategies--to vaccinate or not to vaccinate. We simulated the expected consequences of vaccination on direct medical costs, related to disease management and indirect costs, related to lost parental working days (absenteeism).

RESULTS

Using base-case assumptions vaccination of high-risk children aged 6 months to 15 years old, in Argentina (estimated cohort of 1184748) would prevent 207331 cases of influenza, resulting in a reduction of 58052 days of hospitalization and 207331 outpatient visits. Vaccination would lead to net savings of US$ 11894870 per vaccinated cohort (US$ 10.04 per vaccinated child).

CONCLUSION

our economic analysis shows that in Argentina, routine vaccination of high-risk children against influenza would be cost saving for society.

Comparison of immunogenicity and safety of a virosome influenza vaccine with those of a subunit influenza vaccine in pediatric patients with cystic fibrosis

The objective of this study was to compare the immunogenicity and safety of a single-dose regimen and a two-dose regimen of a trivalent virosome influenza vaccine (Inflexal Berna V) with those of a trivalent subunit influenza vaccine (Influvac) in children and adolescents with cystic fibrosis (CF). In an open, randomized, multicenter study with parallel groups, 11 young children with CF (1 to 6 years old) and 53 older children and adolescents with CF (>6 years old) were randomly assigned to one of the following immunization regimens: virosome vaccine at 0.5 ml on study day 0 or 0.25 ml on days 0 and 28 or a standard regimen of subunit vaccine, i. e., 0.5 ml on day 0 for older children and 0.25 ml on days 0 and 28 for younger children. Safety assessments, i.e., recording of systemic and local adverse events (AEs) and vital signs, were made for a 5-day observation period after each immunization. Hemagglutination inhibition (HI) titers were determined at baseline and 4 weeks after the single-dose and the two-dose immunizations, respectively. Immunogenicity was assessed according to the criteria of the European Agency for the Evaluation of Medicinal Products (EMEA). Both vaccines induced comparable HI antibody titers. Seroconversion (> or =4-fold rise in HI antibody titers, reaching a titer of > or =1:40) was achieved in 41 to 100% of the participants. Seroprotection (HI titer, > or =1:40) and a >2.5-fold increase in geometric mean titers were achieved in 100% of the participants. Thus, all three EMEA requirements for influenza vaccine efficacy were met by all treatment groups and for both vaccines. The virosome vaccine, when administered as a single dose, seemed to induce superior immunogenicity compared with the standard pediatric two-dose regimen. Totals of 42 and 57% of vaccinees receiving virosome and subunit vaccines, respectively, reported at least one local AE (predominantly pain). Totals of 84 and 71% of subjects receiving virosome and subunit vaccines, respectively, complained in response to questions of at least one systemic AE (mainly cough, fatigue, coryza, or headache). The majority of events were mild or moderate and lasted 1 or 2 days only. No obvious relationship was found between AE reporting rate and vaccine formulation, age group, or dose regimen. The relatively high AE reporting rate seemed to be partly related to the symptomatology of the underlying CF disease. In summary, the virosome and subunit vaccines induced in both age groups and against all three influenza strains an efficient immune response and were well tolerated by the children and adolescents with CF.

Vaccines for preventing influenza in people with cystic fibrosis

BACKGROUND

Viral respiratory tract infections in patients with cystic fibrosis have a deteriorating effect on their lung function and disease progression. Annual influenza vaccination is therefore commonly recommended for patients with cystic fibrosis.

OBJECTIVES

To assess the effectiveness of influenza vaccination for patients with cystic fibrosis.

SEARCH STRATEGY

We have used the Cochrane Cystic Fibrosis and Genetic Disorders Group specialist trials register which comprises references identified from comprehensive electronic database searches, hand searching relevant journals and abstract books of conference proceedings and communication to the drug companies marketing influenza vaccines.

SELECTION CRITERIA

All randomised and pseudorandomised trials (published or unpublished) comparing any influenza vaccine with a placebo or with another type of influenza vaccine.

DATA COLLECTION AND ANALYSIS

Both reviewers independently assessed trial quality and extracted data. Additional information were obtained by contacting the investigators when it was indicated.

MAIN RESULTS

Three trials enrolling a total of 115 patients with cystic fibrosis (76 (66%) were children aged one to 13 years) were included in this review. There was no study comparing a vaccine to a placebo or a whole virus vaccine to a sub unit or split virus vaccine. Two studies compared an intranasal applied live vaccine to an intramuscular inactivated vaccine and one study compared a split virus to a sub unit vaccine (both intramuscular). The incidence of all reported adverse events was high depending on the type of influenza vaccine. The total adverse event rate ranged from 48/201 (24%) for the intranasal live vaccine to 13/30 (43%) for the split virus vaccine. With the limitation of a statistical low power there was no significant difference between the study vaccinations. None of the events were severe. All study influenza vaccinations generated a satisfactory serological antibody response. No trial reported other clinically important benefits.

REVIEWER'S CONCLUSIONS

There is currently no evidence from randomised studies that influenza vaccine given to patients with cystic fibrosis is of benefit to them. There is a need for a well constructed clinical study, that assesses the effectiveness of influenza vaccination on important clinical outcome measures.

Variability of human systemic humoral immune responses to adenovirus gene transfer vectors administered to different organs

Administration of adenovirus (Ad) vectors to immunologically naive experimental animals almost invariably results in the induction of systemic anti-Ad neutralizing antibodies. To determine if the human systemic humoral host responses to Ad vectors follow a similar pattern, we evaluated the systemic (serum) anti-Ad serotype 5 (Ad5) neutralizing antibodies in humans after administration of first generation (E1(-) E3(-)) Ad5-based gene transfer vectors to different hosts. AdGVCFTR.10 (carrying the normal human cystic fibrosis [CF] transmembrane regulator cDNA) was sprayed (8 x 10(7) to 2 x 10(10) particle units [PU]) repetitively (every 3 months or every 2 weeks) to the airway epithelium of 15 individuals with CF. AdGVCD.10 (carrying the Escherichia coli cytosine deaminase gene) was administered (8 x 10(8) to 8 x 10(9) PU; once a week, twice) directly to liver metastasis of five individuals with colon cancer and by the intradermal route (8 x 10(7) to 8 x 10(9) PU, single administration) to six healthy individuals. AdGVVEGF121.10 (carrying the human vascular endothelial growth factor 121 cDNA) was administered (4 x 10(8) to 4 x 10(9.5) PU, single administration) directly to the myocardium of 11 individuals with ischemic heart disease. Ad vector administration to the airways of individuals with CF evoked no or minimal serum neutralizing antibodies, even with repetitive administration. In contrast, intratumor administration of an Ad vector to individuals with metastatic colon cancer resulted in a robust antibody response, with anti-Ad neutralizing antibody titers of 10(2) to >10(4). Healthy individuals responded to single intradermal Ad vector variably, from induction of no neutralizing anti-Ad antibodies to titers of 5 x 10(3). Likewise, individuals with ischemic heart disease had a variable response to single intramyocardial vector administration, ranging from minimal neutralizing antibody levels to titers of 10(4). Evaluation of the data from all trials showed no correlation between the peak serum neutralizing anti-Ad response and the dose of Ad vector administered (P > 0.1, all comparisons). In contrast, there was a striking correlation between the peak anti-Ad5 neutralizing antibody levels evoked by vector administration and the level of preexisting anti-Ad5 antibodies (P = 0.0001). Thus, unlike the case for experimental animals, administration of Ad vectors to humans does not invariably evoke a systemic anti-Ad neutralizing antibody response. In humans, the extent of the response is dictated by preexisting antibody titers and modified by route of administration but is not dose dependent. Since the extent of anti-Ad neutralizing antibodies will likely modify the efficacy of administration of Ad vectors, these observations are of fundamental importance in designing human gene therapy trials and in interpreting the efficacy of Ad vector-mediated gene transfer.

Effects of viral lower respiratory tract infection on lung function in infants with cystic fibrosis

OBJECTIVE

To determine the effect of respiratory viral infections on pulmonary function in infants with cystic fibrosis (CF) after the respiratory virus season (October through March).

METHODS

Recruitment was for one respiratory virus season during a 3-year span, 1988 to 1991, with reenrollment allowed; 22 infants <2 years of age with CF (30 patient-seasons) and 27 age-matched controls (28 patient-seasons) participated. Primary outcome variables were preseason and postseason pulmonary function tests and serology for viral antibodies. Twice-weekly telephone calls screened for respiratory symptoms. The presence of respiratory symptoms triggered a home visit and an evaluation for upper or lower (LRTI) respiratory tract infection. A nasopharyngeal sample for viral culture was performed with each visit.

RESULTS

Controls and CF infants each had a mean of 5.3 acute respiratory illnesses; CF infants were four times more likely to develop an LRTI compared with controls (odds ratio, 4.6; 95% confidence interval, 1.3 and 16.5). Three of 7 (43%) CF infants with respiratory syncytial virus infection (documented by culture) required hospitalization. Controls had no association between respiratory illness and postseason pulmonary function. For CF infants, reduced postseason maximal flow at functional residual capacity (V'maxFRC) was associated with two interactions, ie, respiratory syncytial virus infection and LRTI, and male sex and LRTI; increased gas trapping (FRC) was associated with an interaction between respiratory syncytial virus and LRTI and day care. Postseason pulmonary function tests were obtained a mean of 3. 2 months after final LRTI.

CONCLUSIONS

Infants with CF incurring respiratory virus infection are at significant risk for LRTI, for hospitalization, and for deterioration in lung function that persists months after the acute illness.

Severe viral respiratory infections in infants with cystic fibrosis

Limited data in children with cystic fibrosis (CF) suggest that respiratory viral infections during infancy result in substantial morbidity. Eighty of 101 (79%) infants with CF diagnosed by neonatal screening during 1991-1996 were recruited into a prospective, multiple-birth cohort study. We aimed to perform an initial, then annual bronchoalveolar lavage (BAL) for bacterial and viral culture, cytology, IL-8, and elastolytic activity over the following 2 years. When possible, BAL was also performed during any hospitalization for a pulmonary exacerbation, and additional specimens for viral culture were collected by nasopharyngeal aspiration. Thirteen infants undergoing bronchoscopy for congenital stridor served as disease controls. During infancy, 31 children (39%) were hospitalized for respiratory disease and 20 (65%) cases had an etiologic agent identified. Respiratory viruses were detected in 16/31 (52%) cases, including four with simultaneous bacterial infection. Another four were infected with Staphylococcus aureus. Respiratory syncytial virus predominated and was found in seven infants. In the absence of bacteria, those with viral infections had acute onset of respiratory distress, were not treated with antibiotics, and had an uncomplicated hospital course. Compared to noninfected CF subjects and controls, infected infants had elevated BAL inflammatory indices (P < 0.01). Eleven of 31 (35%) hospitalized infants followed for 12-60 months acquired Pseudomonas aeruginosa, compared with only three of 49 (6%) subjects not hospitalized for respiratory symptoms during infancy (risk ratio 5.8, CI 1.9, 24). We conclude that respiratory viruses are important causes of hospitalization in CF infants. While viral infections were self-limited, they were accompanied by airway inflammatory changes, and admission to hospital was associated with early acquisition of Pseudomonas aeruginosa and persistent respiratory symptoms.

Whole virus influenza vaccine activates dendritic cells (DC) and stimulates cytokine production by peripheral blood mononuclear cells (PBMC) while subunit vaccines support T cell proliferation

Three types of trivalent influenza vaccines were analysed for their in vitro stimulatory properties on immune cells from young healthy volunteers. A whole inactivated virus (WV) vaccine, a conventional subunit (c-SU) preparation and a new virosomal subunit (v-SU) vaccine were used. Blood-derived DC up-regulated MHC class II, CD54, CD80 and CD86 after exposure to WV vaccine, indicating their functional maturation, but were only moderately affected by subunit (SU) vaccines. In addition, IL-12 and tumour necrosis factor-alpha (TNF-alpha) secretion by DC were markedly enhanced by WV, but not by SU vaccines. The production of IL-2 and interferon-gamma (IFN-gamma) by PBMC was also strongly stimulated by WV, but much less by SU vaccines, among which the v-SU vaccine was a better stimulator of IL-2 secretion. In contrast to WV vaccine both SU vaccines were powerful stimulators of PBMC proliferation. Our results suggest that the presence of influenza core components leads to the activation of DC and triggers the production of cytokines by PBMC. SU vaccines are in contrast excellent stimulators of T cell growth. A combination of WV and SU vaccines in immunization regimes might allow optimal T cell priming as well as the efficient generation and maintenance of memory cells.

Incidence and prevalence of neutralizing antibodies to the common adenoviruses in children with cystic fibrosis: implication for gene therapy with adenovirus vectors

OBJECTIVE

Defining the infection rate and prevalence of the common adenoviruses (Ads) in cystic fibrosis (CF) children may aid in formulation of strategies for gene therapy with Ad vectors. We undertook this study to determine the incidence and prevalence of infection with the common Ads in children with CF.

METHODOLOGY

Thirty newly diagnosed CF children mean age 1.1 years (Group 1), 48 CF children mean age 4.6 years (Group 2), and 47 mothers of CF children (Group 3) were followed for a mean of 13 months. Group 4 consisted of 33 adult volunteers seen once. Throat and stool specimens for virus culture, and blood samples were obtained every 3 months from CF children in Group 1. Blood samples from CF children (Group 2) and their mothers (Group 3) were obtained every 6 months, and once from adults in Group 4. Neutralizing antibody to Ad serotypes 1 through 7 (Ad 1 to Ad 7) was evaluated with a microneutralization assay.

RESULTS

Five (16.7%) CF children in Group 1 were culture-positive for an Ad; 4 of these CF children developed a fourfold or greater rise in antibody titer. Ad 3 infection occurred frequently based on serology; seronegative (< 3.5 log 2) CF children had a higher infection rate compared with seropositive CF children (7/11 vs 1/34). The prevalence of neutralizing antibodies in CF children in order of decreasing frequency was 91.1% to Ad 3, 37.5% to Ad 2, 27.1% to Ad 1, 26.1% to Ad 7, 16.7% to Ad 5, 8.5% to Ad 4, and 2.0% to Ad 6. The neutralizing antibody titers in seropositive CF children were comparable to those in adults except to Ad 3, which was significantly greater in mothers of CF children.

CONCLUSIONS

CF children had a normal antibody response after Ad infection, preexisting antibody may protect against reinfection and antibody prevalence was low to the common Ads.

PICNIC (Pediatric Investigators Collaborative Network on Infections in Canada) study of the role of age and respiratory syncytial virus neutralizing antibody on respiratory syncytial virus illness in patients with underlying heart or lung disease

OBJECTIVE

To determine the effects of age and respiratory syncytial virus (RSV) antibody status on frequency and severity of RSV infections in children with underlying heart or lung disease.

DESIGN

Cohort study conducted during two consecutive RSV seasons.

SETTING

Ambulatory patients at eight Canadian pediatric tertiary care centers.

METHODS

Subjects under 3 years old with underlying heart disease who were digoxin-dependent or had not received corrective cardiac surgery or with underlying lung disease were enrolled. Demographic information and an acute sera for RSV neutralizing antibody was obtained on enrollment. Weekly telephone follow-up consisting of a respiratory illness questionnaire was followed with a home visit to obtain a nasopharyngeal aspirate when there was new onset of respiratory symptoms. The specimen was used to detect RSV antigen. RSV illnesses were grouped as upper or lower respiratory tract infection (LRI) based on clinical and radiographic findings. RSV hospitalizations were considered to be those RSV infections that resulted in hospitalization.

RESULTS

Of 427 enrolled subjects, 160 had underlying lung disease only, 253 had underlying heart disease only, and 14 had both. Eleven percent and 12% of lung and heart disease groups, respectively, had an RSV LRI. Three percent and 6% of lung and heart disease groups, respectively, were hospitalized with RSV infection. A significant decrease in frequency of RSV LRI and RSV hospitalization occurred with increasing age, with a major drop in those older than 1 year vs those younger than 1 year. Acute sera were available from 422 subjects. Geometric mean RSV antibody titers demonstrated a U-shaped distribution with increasing age. The trend to lower antibody concentrations in premature infants did not reach statistical significance. The frequency of RSV infection and RSV LRI was lower in patients with antibody at a titer more than 100, although the difference for RSV hospitalization was not statistically significant. These differences remained significant after age adjustment.

CONCLUSION

Both age and RSV antibody status impact on RSV illness and LRI. Reduction in illness frequency with increasing age may lead to more informed targeting of those children most likely to benefit from RSV immune globulin prophylaxis.

Potential of preventing Pseudomonas aeruginosa lung infections in cystic fibrosis patients: experimental studies in animals

In patients with cystic fibrosis (CF), respiratory tract infections caused by Staphylococcus aureus and Haemophilus influenzae are followed by Pseudomonas aeruginosa with increasing age. Chronic endobronchial lung infection with P. aeruginosa is the leading cause of morbidity and mortality. In Danish CF patients we noted that both onset of initial colonization and chronic lung infection with P. aeruginosa peaked during the winter months which is the season for respiratory virus infections. Virus may therefore pave the way for P. aeruginosa. We established a chronic P. aeruginosa lung infection in rats by embedding mucoid bacteria in seaweed alginate and installing the beads intratracheally into the lower part of the left lung. Although the rats did not suffer from CF, the antibody responses and the pathologic changes of the lungs mimicked the findings in CF patients. By using this model in normal and athymic rats we showed that the T-cell response during the "natural" course of the infection played no major role. In a model of acute P. aeruginosa pneumonia we found that the macroscopic inflammatory response of the lungs was immense and that the natural capacity to clear P. aeruginosa was very efficient and could not be improved by immunization, although high serum levels of IgM, IgG and IgA antibodies to P. aeruginosa alginate, LPS, exotoxin A and sonicate were induced. We developed a method for collecting and measuring IgA in saliva and noted that mucosal IgA antibodies were induced by vaccination; they did not significantly prevent inflammation, however. In the chronic rat model we succeeded to improve the survival significantly and to change the inflammatory response subsequent to vaccination from an acute type inflammation dominated by polymorphonuclear leukocytes (PMNs) as in CF patients to a chronic type inflammation dominated by mononuclear leukocytes. Furthermore, we found that rats immunized with an alginate containing vaccine had a significantly earlier cellular shift to a chronic type inflammation as well as a significant reduction in the severity of the macroscopic inflammation compared to two other vaccine groups and to nonimmunized controls. Similar results were obtained in rats treated with the TH1 cytokine, interferon-gamma (IFN-gamma). Several authors have shown that the lung tissue damage during chronic infection in CF patients is caused by a type III hypersensitivity reaction leading to release of elastase by PMNs surrounding the bacterial microcolonies. The cellular shift we have induced by vaccination and by IFN-gamma treatment therefore offers a possible new strategy for improving the clinical course in chronically infected CF patients.

Infection of A549 cells with a recombinant adenovirus vector induces ICAM-1 expression and increased CD-18-dependent adhesion of activated neutrophils

A significant number of pulmonary exacerbations in patients with cystic fibrosis (CF) and asthma are associated with respiratory virus infections. The molecular mediators of this process are beginning to be understood. Viral infection of respiratory epithelial cultures in vitro leads to the production of intercellular adhesion molecule-1 (ICAM-1) (a ligand for inflammatory cell adhesion and activation) and a number of proinflammatory cytokines. Human gene therapy vectors derived from human adenoviruses (AV) are currently under evaluation for CF transmembrane regulator (CFTR) gene delivery to the airway epithelium of CF patients. However, studies in animal models using these AV vectors demonstrate pulmonary inflammation following AV exposure. Using an in vitro model, we examined the hypothesis that exposure of respiratory epithelial cells to AV vectors results in upregulation of ICAM-1 gene expression. Infections were performed using a replication-deficient, first-generation AV vector. A549 cells (a human pulmonary adenocarcinoma cell line) were exposed to AV at multiplicity of infection of 50-150 plaque-forming units/cell (resulting in > 90% of cells expressing the reporter gene by 48 hr following exposure). Measurements of ICAM-1 expression were made at time intervals following virus exposure using enzyme immunoassay, flow cytometry, and Northern blot analysis. Cell-bound ICAM-1 was significantly increased 96 hr following vector exposure, two to four times control, p < 0.001). The AV-exposed A549 cells also supported increased levels of adhesion of activated neutrophils 96 hr following AV exposure (four times control, p < 0.001) that was blocked by antibody to CD18. AV exposure of A549 monolayers increases expression of biologically active ICAM-1. Strategies to minimize host cellular proinflammatory responses to the replication-deficient AV vectors may improve their safety for gene therapy.

Annual influenza vaccination: immune response in patients over 10 years

OBJECTIVE

To determine the effect of repeated annual influenza immunization on the host's serum antibody.

DESIGN

Ten year observational study with cohort design.

SETTING

Cystic Fibrosis Center at St. Vincent's Hospital and Medical Center, New York City, NY.

PATIENTS

Thirty-eight children and young adults with cystic fibrosis (CF).

MEASUREMENTS

Serum hemagglutination inhibition (HI) antibody titers were determined at the time of vaccination and 4 weeks later each year in the fall before the influenza epidemic. Shwachman scores were determined each year.

RESULTS

While the pre-vaccination and post-vaccination geometric mean serum HI antibody titers varied from year to year, no upward or downward trend was evident over the 10 year period. The reciprocal of the post-vaccination geometric mean HI titers ranged annually from 32 to 74 for the influenza A (H3N2) vaccine strains, from 53 to 133 for the influenza A (H1N1) strains, and from 18 to 174 for influenza B strains. In addition, the majority of vaccinees had a presumably protective post-vaccination serum HI titer > or = 1:40 each year for all three vaccine strains. The initial mean Shwachman score of the group was 77. The final score of 76 after 10 years was not significantly different.

CONCLUSIONS

Annual influenza vaccination appears to regularly induce presumably protective serum antibody levels in most CF children and young adults studied over a 10 year period.

Adenovirus infection in cystic fibrosis patients: implications for the use of adenoviral vectors for gene transfer

Clinical trials using replication-deficient adenovirus as vectors for gene transfer into the airways of cystic fibrosis (CF) patients are in progress. However, little is known about the prevalence of wild-type adenovirus infections in patients with cystic fibrosis and their effect on lung function. To answer these questions, serum IgG and IgM antibody titers against adenovirus type 5 were prospectively measured by an indirect immunofluorescence assay in 199 CF outpatients and in a control group of 45 healthy children and young adults. In addition, we performed pulmonary function tests when the patients were in stable clinical condition. IgM antibodies against adenovirus were present in 104 of the 199 cystic fibrosis patients (52.3%). IgG antibodies against adenovirus were detected in 192 of the 199 cystic fibrosis patients (96.5%), and were significantly higher in cystic fibrosis patients older than 7 years than in younger patients and in age matched controls. IgG antibody titers measured a second time 11.8 months later in 143 of the 199 patients had increased in 48 (33.6%) patients. In 27 of these 48 patients, who had at least a 2-fold increase in antibody titer, FVC and FEV1 decreased by 9.8% (p < 0.05) and 8.3% (p = 0.05), respectively, over 45 months. In a comparison group matched for age, sex, and chronic Pseudomonas aeruginosa infection but no increase in antibody titers, FVC and FEV1 were unchanged. The results indicate that wild-type adenovirus infections are prevalent in cystic fibrosis patients and that wild-type adenovirus infections in cystic fibrosis patients seem to be associated with deterioration in lung function. These observations may have important implications for efficacy and safety considerations when using adenoviral vectors for gene therapy.

Purified fusion protein vaccine protects against lower respiratory tract illness during respiratory syncytial virus season in children with cystic fibrosis

OBJECTIVE

To test in a double blind, placebo-controlled study a purified fusion protein (PFP-2) vaccine against respiratory syncytial virus (RSV) in RSV-seropositive children with cystic fibrosis (CF).

METHODS

Seventeen CF children, mean age 4.5 years, received PFP-2 vaccine and 17 CF children, mean age 5.8 years, received a saline vaccine. At enrollment the Shwachman clinical score, Brasfield radiographic score, oxygen saturation (SpO2), anthropometric indices and other variables were recorded. After vaccination the reactions were assessed daily for 7 days. During the RSV season weekly telephone interviews were performed and children with an acute respiratory illness were evaluated and cultured for RSV. Serum was drawn before vaccination, 1 month after vaccination and at the end of the RSV season and tested for antibodies to RSV.

RESULTS

Other than age the baseline measurements at enrollment were similar between groups. The PFP-2 vaccine produced mild local reactions and induced a significant neutralizing antibody response in two-thirds of the vaccinees and a significant enzyme-linked immunosorbent assay-fusion glycoprotein antibody response in nearly all the PFP-2 vaccinees. Vaccine-enhanced disease was not observed in PFP-2 vaccines infected with RSV. Protection against RSV infection was not observed; however, a significant reduction (t test, P < 0.01) in mean number of lower respiratory tract illnesses (0.8 vs. 2.1), antibiotic courses (2.2 vs 4.5) and days ill (30.5 vs. 67) occurred among RSV-infected PFP-2 vaccinees.

CONCLUSIONS

Efficacy of the PFP-2 vaccine against lower respiratory tract illness during the RSV season was shown in RSV-seropositive children with CF.

Short-term and long-term effects of albuterol aerosol therapy in cystic fibrosis: a preliminary report

The effectiveness of maintenance albuterol aerosol therapy in cystic fibrosis (CF) was assessed by comparing spirometric measurements at the beginning and end of 1 year. Peak expiratory flow rates (PEFR) were measured twice daily to determine bronchodilator responsiveness and spontaneous diurnal variation (SDV), and results were compared with groups of normal and asthmatic children. CF patients not receiving regular albuterol therapy served as a control group. In the treatment group, forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1) were significantly increased (12.2% and 18.4%, respectively) over the course of the treatment year, as contrasted with a significant decrease during the preceding year. During the study year the CF control group had a significant decrease in FEV1 and FEF25-75%, and the difference between treatment and control groups was significant for FVC, FEV1, and FEF25-75%. PEFR increased from the first to the last week of the year-long observation period (from 71.8% to 78.7% of predicted values, P < 0.01). Spontaneous diurnal variations were significantly greater in the CF study group than a group of normal children; SDV decreased significantly in the treatment group during the year of study. A bronchodilator response of > 15% was present in 25.8% of CF patient days, but there was considerable interpatient variability. Frequent bronchodilator responders were accurately predicted by their baseline bronchodilator responsiveness, but not by age or personal or family history of asthma or atopy. No difference in long-term pulmonary function improvements were noted between frequent and infrequent responders. The results suggest that maintenance albuterol aerosol treatments reversed the progressive downward course in lung function in the CF treatment group. A double-blind placebo-controlled study is required to confirm these preliminary findings.

Effect of respiratory virus infections including rhinovirus on clinical status in cystic fibrosis

One hundred and eight patients with cystic fibrosis were investigated over one year to determine whether an association existed between rhinovirus or other respiratory virus infection and clinical status. Forced expiratory volume in one second (FEV1), forced vital capacity (FVC), Shwachman score, Chrispin-Norman chest radiograph score, and percentage weight for height were recorded at the beginning and end of the study; days of intravenous antibiotics were noted. Nasopharyngeal aspirates were taken for viral studies during respiratory exacerbations. Serum was collected at enrollment and 2-6 weeks after each respiratory exacerbation. One hundred and fifty seven exacerbations occurred in 76 patients. Respiratory virus infection was detected in 44 exacerbations and rhinovirus was present in 16% (25/157) of exacerbations. Patients with one or more respiratory virus infections were compared with those who had none. When all respiratory virus infections were considered, patients had a significantly greater deterioration in Shwachman score and received significantly more days of intravenous antibiotics. When rhinovirus was considered separately, patients received significantly more days of intravenous antibiotics, but showed no deterioration in clinical status. However, patients infected with another respiratory virus had a significant decline in FEV1, with trends towards significance for decline in FVC and Shwachman score.

New perspectives in understanding and management of the respiratory disease in cystic fibrosis

In the past 40 years, the mean survival of patients with cystic fibrosis (CF) has increased from less than 1 year to 30 years. The identification of the gene mutated in CF in 1989 has already been followed by the first phase of somatic gene therapy in 1993. The target organ of somatic gene therapy is the respiratory epithelium, which is progressively damaged by the chronic infection and inflammation characteristic of the disease. Since in the future, more patients may benefit from somatic gene therapy, the understanding of the mechanisms leading to chronic infection and inflammation becomes increasingly important. In the future, current therapeutic measures to protect the respiratory epithelium from damage, such as intravenous antimicrobial treatment, will be improved by the additional delivery of new drugs to the bronchial tree by aerosol. Amiloride and recombinant human DNAse administered by this route have the potential to improve mucociliary clearance. Antibiotics as well as protease inhibitors delivered by aerosol should contribute to prevent damage by infection and inflammation in order to increase the probability of successful somatic gene therapy in this disease.

Allergic bronchopulmonary aspergillosis in patients with cystic fibrosis

In order to determine the incidence of allergic bronchopulmonary aspergillosis (ABPA) in patients with cystic fibrosis (CF), we reviewed the records of 236 patients followed up at the Duke CF Center. Sixty patients (25 percent) had colonies of Aspergillus fumigatus. These patients were older and had more severe disease as assessed by lower Shwachman-Kulczycki (S-K) scores than the patients who did not have evidence of A fumigatus. In 15 of the patients with A fumigatus (6.5 percent of the total population), the diagnosis was ABPA. Age and S-K scores were not significantly different from those of the patients with A fumigatus without ABPA. Diagnostic features of the affected patients included wheezing refractory to bronchodilator therapy, persistent pulmonary infiltrates, peripheral eosinophilia, positive skin reactivity to an A fumigatus antigen and elevated total serum IgE levels. Steroid therapy was started for all patients, and clinical improvement was noted within 1 month as evidenced by decreased symptoms and weight gain. Chest x-ray films usually showed improvement. Vital capacity improved in all but two patients. Total IgE did not consistently decrease in response to therapy. Although the diagnosis of ABPA may be difficult to establish, ABPA commonly is associated with CF. Most patients respond to steroid therapy; however, the effect of therapy on the course of the disease is difficult to assess.

Impact of respiratory virus infection in patients with chronic chest disease

This study investigated the morbidity associated with respiratory virus infections in patients with well-documented chest disease, and the risk of transmission between close contacts. Patients informed the study team if they were exposed to a family member or colleague with a cold. Patients and symptomatic index cases recorded respiratory symptoms during the study period. Acute nasopharyngeal swabs and paired sera were obtained for viral diagnosis. Twenty-five (43%) of 58 recorded exposures resulted in a symptomatic illness and 16 (28%) patients developed lower respiratory tract symptoms. Sixteen (64%) of the 25 symptomatic patients contacted their general practitioner, 14 (56%) received antibiotics and 4 (16%) were hospitalized. Mean duration of illness was 10.6 days in symptomatic patients and 5.7 days in their corresponding index cases (P < 0.005). Mean symptom scores were 100.6 in symptomatic patients and 62.2 in index cases (P < 0.01). Respiratory viruses were identified in 19 (33%) episodes. Rhinovirus, coronavirus and respiratory syncytial virus infections were all associated with lower respiratory tract exacerbations. Respiratory tract symptoms following exposure to a cold were comparatively severe in these patients with chronic chest disease. This group of patients might gain particular benefit from the introduction of effective vaccines or antiviral therapy.

Cystic fibrosis

Cystic fibrosis, an autosomal recessive disorder, is the most common genetic disease of Caucasians. One in 25 Caucasians are carriers of the gene. The gene is found far less commonly in other races. There are over 230 different alleles of the gene, located on the 7th chromosome. The gene encodes for a membrane protein that functions as an ion channel. The survival of cystic fibrosis patients has been gradually increasing, with a mean survival in 1990 of 28 years. If the current trend of improved survival continues, it is estimated that half of cystic fibrosis patients will be over 18 years old by 1996. Disease is found in many organs including the lungs, sinuses, pancreas, gastrointestinal tract, hepatobiliary system, sweat glands and reproductive tract. The majority of patients die of pulmonary disease. The airways become chronically colonized with bacteria that cannot be eradicated, leading to bronchitis, bronchiectasis, and finally, pulmonary fibrosis with respiratory failure. The pulmonary disease may be complicated by massive hemoptysis and pneumothorax. Patient survival rates have increased because of antibiotic therapy and improved nutrition with pancreatic enzyme replacements. New treatments for the pulmonary disease are under clinical trial and include antiproteases, amiloride, a sodium channel blocker, and DNase. The insertion of the normal cystic fibrosis allele into an animal model using a modified adenovirus with effective transcription suggests that gene therapy may be possible in the future, but safety and technical problems have to be addressed.

Acute severe deterioration in cystic fibrosis associated with influenza A virus infection

BACKGROUND

The role of non-bacterial infection in respiratory exacerbations of cystic fibrosis has been studied less than that of bacterial infection. Some non-bacterial infections, such as influenza A, may be associated with acute respiratory deterioration and may be preventable.

METHODS AND RESULTS

Three patients with cystic fibrosis showed severe deterioration in lung function and general wellbeing during the influenza A virus epidemic in the winter of 1989-90. Serological confirmation of influenza A virus infection was obtained in each case.

CONCLUSIONS

As immunisation against influenza A virus is safe and provokes an adequate antibody response in patients with cystic fibrosis, it is concluded that patients with cystic fibrosis should be offered immunisation at the beginning of each influenza season. Rapid diagnostic tests and the use of antiviral drugs may have a prophylactic role in minimising lung damage.

Sputum cysteinyl-leukotriene levels correlate with the severity of pulmonary disease in children with cystic fibrosis

Sputum samples from 13 children with cystic fibrosis (CF) were analyzed for leukotrienes (LTs) LTB4, LTC4, LTD4, and LTE4. Distribution of LTB4 appeared to be normal, and of cysteinyl-LTs log normal. Total cysteinyl-LT levels, of which on average 75% was LTE4, were nearly 10 times higher than in earlier studies. Log LTE4 and total cysteinyl-LT levels correlated with the overall severity of pulmonary disease assessed by Chrispin-Norman chest radiograph score (Log LTE4: r = 0.701, r2 = 49.1%, P = 0.008. Log total cysteinyl-LTs: r = 0.715, r2 = 51.1%, P = 0.006). There was no apparent relationship between LTB4 levels and Chrispin-Norman chest radiograph score, nor between the level of any of the LTs and age or organism cultured from sputum. These findings suggest that the cysteinyl-LTs may be involved in the pathophysiology of pulmonary disease in CF.

Impact of influenza on morbidity in children with cystic fibrosis

Recommendations concerning annual influenza vaccination in children suffering from cystic fibrosis (CF) are not uniform. Previous studies have shown that influenza causes a small proportion of episodes of acute respiratory deterioration in CF patients. During the 1989 Australian winter, we studied the association between serologically proven influenza infection and acute respiratory morbidity in 20 children with CF. Six children were shown to have influenza infection, four with type A and two with type B. Four of five children requiring hospital admission were shown to have influenza, but only 2 of 15 did not need admission (P less than or equal to 0.025). As well, influenza was diagnosed in 6 of 12 children who suffered acute respiratory illness leading to school absenteeism (including hospitalization), but diagnosed in no children without this degree of illness (P less than or equal to 0.025). Influenza significantly increases the incidence of hospitalization and of less serious respiratory illness in children with CF, a finding which suggests that influenza vaccine efficacy studies are necessary in this group.

Cystic fibrosis. Infection and immunity to Pseudomonas

Chronic pulmonary infection with P. aeruginosa in CF may result from: 1. An initial failure of clearance mechanisms (increased adherence) leading to the development of a highly compartmentalized inflammatory reaction; 2. Inhibition of clearing mechanisms for bacteria present in the bronchial lumen; and 3. A largely ineffective, and possibly damaging, hyperactivity of inflammatory cells in the lumen and bronchial wall. The special relationship between the CF host and P. aeruginos, always long-term, and frequently subtle in its complexity, needs further understanding in order to develop new strategies for the treatment of chronic lung infections with this organism.

Varicella-zoster infection in adults with cystic fibrosis: role of acyclovir

Of 159 adult patients with cystic fibrosis, 5 were documented to have varicella-zoster infection that resulted in an infective pulmonary exacerbation that required intravenous acyclovir and additional antibiotic treatment. Stable serial pulmonary function values were observed over a 1-year period in 4 patients and no complications resulted from treatment. Early treatment with acyclovir in combination with appropriate antibiotics may prevent pulmonary deterioration in adult patients with cystic fibrosis who develop varicella-zoster infection.

Microbiology of airway disease in patients with cystic fibrosis

Individuals with cystic fibrosis have abbreviated life spans primarily due to chronic airway infection. A limited number of types of organisms are responsible for these infections, with Staphylococcus aureus and Pseudomonas aeruginosa being of primary importance. In the pre-antibiotic era, greater than 90% of deaths due to infection were caused by S. aureus and death usually occurred in the first 2 years of life. With the advent of effective antistaphylococcal therapy, life spans increased and P. aeruginosa became the pathogen of primary importance. P. aeruginosa isolates recovered from patients with cystic fibrosis have a unique phenotypic characteristic referred to as "mucoid." The mucoid phenotype is due to the production of a mucoid exopolysaccharide. A mucoid exopolysaccharide is believed to play a central role in the establishment of chronic pseudomonal lung infection in these patients. A third organism, Pseudomonas cepacia, has recently been detected in the airways of older patients with cystic fibrosis and is associated with increased mortality. The virulence of P. cepacia is not understood, but the organism is extremely refractory to antimicrobial therapy. Other bacteria, including Haemophilus influenzae and members of the family Enterobacteriaceae, appear to play a secondary role in airway infection. Aspergillus fumigatus is the most important fungal agent causing allergic bronchopulmonary disease. The role of viruses has only recently been examined. At least in some patients with cystic fibrosis, respiratory syncytial virus may be important in predisposing to subsequent bacterial infections.

Clinical manifestations of exacerbations of cystic fibrosis associated with nonbacterial infections

The purpose of this study was to determine whether acute pulmonary exacerbations of cystic fibrosis associated with nonbacterial infections are clinically distinguishable from other exacerbations. Eighty exacerbations in 54 patients were studied. Exacerbations associated with influenza (n = 8) were compared with those associated with other nonbacterial infections (n = 15) and those in which no nonbacterial infection was detected (n = 57). Patients with influenza had lower Shwachman scores and were more likely to be seropositive for C-reactive protein than patients in the other two groups. Patients with influenza had a mean decrease in forced expiratory volume per second of 26%, compared with test results obtained before the exacerbation. In contrast, the mean decrease in forced expiratory volume per second was 6% for other nonbacterial infections and 12% for the group without nonbacterial infection (p less than 0.05 for both comparisons). The forced expiratory flow in first 25% of vital capacity decreased 44% in the influenza group compared with 13% and 17% in the other two groups, respectively (p less than 0.01 for both comparisons). The influenza group also had a higher proportion of patients with at least a 20% decrease in forced expiratory volume per second and forced expiratory flow in first 25% of vital capacity than the other two groups had (p less than 0.05 for all comparisons). These data suggest that influenza is associated with severe exacerbations in patients with cystic fibrosis and support recommendations for efforts to prevent influenza in this population.

Haemophilus infection in cystic fibrosis

Twenty seven patients with cystic fibrosis under the age of 12 years and 27 matched patients with asthma were followed up in a prospective study for one year. The isolation rate of non-capsulated strains of Haemophilus influenzae from cough swabs and sputum specimens taken at routine clinic visits every two months was significantly greater in cystic fibrosis than in asthma. Haemophilus para-influenzae was equally common in both groups. During exacerbations the isolation rate of H influenzae in cystic fibrosis was significantly greater than at other times, whereas in asthma there was no significant difference. The distribution of biotypes of H influenzae and H parainfluenzae was similar in the two groups. In cystic fibrosis, biotype I was associated with exacerbations. Biotype V was more common than in previous studies, but was not associated with exacerbations.

The impact of respiratory viral infections in patients with cystic fibrosis

Respiratory viruses have been implicated in pulmonary exacerbations of CF and in the long-term course of pulmonary dysfunction in these patients. However, the data are by no means complete and there is the clear need for more intensive evaluations of the role of viral pathogens in this population. Further controlled prospective studies assessing the impact of viral infections in large cohorts of patients with CF are still necessary. Placebo-controlled, antiviral treatment protocols also should be initiated. In clinical practice at the present time, patients with CF should be assessed for respiratory viral infections, at least at the time of hospitalizations for pulmonary deterioration. This assessment should include obtaining specimens from the respiratory tract for viral cultures and rapid respiratory viral antigen detection. Identifying a respiratory viral infection may alter clinical care. The patient can be isolated appropriately, and it may be possible to reduce the intensive use of expensive and potentially toxic parenteral antibiotics. The role of antiviral therapy in these patients must await further evaluations. The mechanisms of the short- and long-term effects of respiratory viruses in patients with CF have not been defined. However, pathophysiologic studies conducted in normal children and adults allow the development of several plausible hypotheses. The definition of mechanisms of injury in this population must be a priority, since it may influence clinical practice. If airway obstruction is the principal mechanism of viral-induced injury, therapeutic approaches designed to relieve the obstruction would be most appropriate. For example, if the obstruction resulted from induced or aggravated reactive airway disease, the current common practice of prescribing chronic bronchodilator therapy would be appropriate. This therapy might be especially suited to those experiencing frequent viral infections. In addition, the administration of bronchodilators to patients during acute exacerbations of pulmonary disease caused by viruses might be of clinical benefit. If, on the other hand, the principal mechanism of viral-induced injury is found to be through synergistic interaction with bacteria, the current practice of aggressive antimicrobial therapy would remain appropriate.

Infective respiratory exacerbations in young adults with cystic fibrosis: role of viruses and atypical microorganisms

Thirty six adults with cystic fibrosis were studied over one year to determine the incidence of infection with respiratory viruses and atypical organisms. Nineteen patients entered the study during an acute exacerbation of respiratory symptoms with an increase in purulent sputum production, cough, or breathlessness accompanied by a fall in FEV1 (group 1); 17 patients entered when they were stable both clinically and in terms of lung function values (group 2). Group 1 patients had a mean of 2.6 (range 1-4) infective exacerbations during the year and group 2 patients a mean of 1.1 (0-2) exacerbations. Eleven patients developed serological evidence of viral (influenza virus A and B, cytomegalovirus, human rhinovirus 2, adenovirus) or Mycoplasma pneumoniae infection. There was no difference in seroconversion rates between group 1 (five patients) and group 2 (six patients). There was a weak association between viral seroconversion and the isolation of Pseudomonas aeruginosa from sputum, though this was not significant.

Effects of acute viral respiratory tract infections in patients with cystic fibrosis

To determine the effects of acute viral respiratory infections (ARI) in cystic fibrosis (CF) we studied all episodes of ARI in ten patients over a 2 year period. A daily diary card was kept on which they recorded all illnesses, including specific upper and lower respiratory symptoms, antibiotic use, and daily peak flow measurements. Recording of concurrent similar illnesses in other household members aided in confirming the onset of ARI, as did a home viral culturing technique and serial serum antibody levels against specific viral types. A total of 80% of the 35 recorded onsets of ARI (1.75/yr/subject) were confirmed by one or more of these methods. Five subjects with moderate to severe pulmonary function scores at the outset of the study had significantly greater decreases in PEFR during ARI episodes (42.4%) than those with milder disease (15.4%), and it took them significantly longer to recover to their baseline measurements (22 days vs. 15 days respectively). The majority of hospital admissions for pulmonary exacerbations were preceded by viral infections (7/8).

The primary care physician and the patient with cystic fibrosis

Although CF has increasingly become a "subspecialty disease," the decisions and practice style of the patient's pediatrician or family physician are extremely important. The primary physician's handling of everything from the timing of infant immunizations to teenage advice about sex and drug abuse have far-reaching medical and psychosocial implications and must be carefully considered.