Epidemiologic study of cystic fibrosis: design and implementation of a prospective, multicenter, observational study of patients with cystic fibrosis in the U.S. and Canada.

Cystic fibrosis (CF) is a complex illness characterized by chronic lung infection leading to deterioration in function and respiratory failure in over 85% of patients. An understanding of the risk factors for that progression and the interaction of these factors with current therapeutic strategies should materially improve the prevention of this progressive lung disease. The Epidemiologic Study of Cystic Fibrosis (ESCF) was therefore designed as a multicenter, longitudinal, observational study to prospectively collect detailed clinical, therapeutic, microbiologic, and lung function data from a large number of CF treatment sites in the U.S. and Canada. The ESCF also serves an important role as a phase-IV study of dornase alfa. To be eligible for enrollment, subjects must have the diagnosis of CF and receive the majority of their care at an ESCF site. In this paper, the authors present the ESCF study design in detail. Further, enrollment data collected at 194 study sites in 18,411 subjects enrolled from December 1, 1993 to December 31, 1995 are presented in summary form. This comprehensive study is unique in the detail of clinical data collected regarding patient monitoring and therapeutic practices in CF care. Two companion articles present data regarding practice patterns in cystic fibrosis care, including data on resource utilization and prescribing practices.

Impact of microbiology practice on cumulative prevalence of respiratory tract bacteria in patients with cystic fibrosis.

Investigators participating in the Epidemiologic Study of Cystic Fibrosis project began to collect microbiological, pulmonary, and nutritional data on cystic fibrosis (CF) patients at 180 North American sites in 1994. Part of this study was a survey undertaken in August 1995 to determine microbiology laboratory practices with regard to pulmonary specimens from CF patients. The survey included a section on test ordering, completed by a site clinician, and a section on test performance and reporting, completed by each site's clinical microbiology laboratory staff. Seventy-nine percent of the surveys were returned. There was intersite consistency of microbiology laboratory practices in most cases. The majority of sites follow most of the CF Foundation consensus conference recommendations. There were differences in the frequency at which specimens for culture were obtained, in the use of selective media for Staphylococcus aureus and Haemophilus influenzae, and in the use of a prolonged incubation for Burkholderia cepacia. These variations in practice contribute to prevalence differences among sites and may result in differences in clinical care.

Proteinase-free myeloperoxidase increases airway epithelial permeability in a whole trachea model.

In cystic fibrosis the bronchiectatic conducting airways have large numbers of neutrophils in their walls and in their luminal contents. The neutrophil's primary granule enzyme activities of elastase and peroxidase are increased in the sputum of these patients. It has been postulated that these enzymes--together or individually--act to damage the airway epithelium. However, only peroxidase activity has consistently correlated with the degree of structural and functional airway disease in these patients with leakage of plasma protein into the airway lumen (Regelmann et al., Pediatr Pulmonol, 1995; 19:1-9). The present study was designed to test whether human neutrophil-derived myeloperoxidase can independently produce bronchial epithelial damage without the presence of proteases, as measured by increased permeability of the airway epithelium. Human peripheral blood neutrophils were purified, their primary granules isolated, and their peroxidase purified using affinity and ion exchange column chromatography. Activity of the proteinase-free peroxidase was measured using a chromogenic substrate. The effect of this peroxidase on the permeability of excised rat tracheas was measured using radioactive and fluorescent-labeled non-ionic molecules of varying molecular weight. Rat tracheas exposed to 15 minute treatments with either 130 U of peroxidase or hydrogen peroxide (10(-5) M) did not show a significant increase in the permeability of the epithelium to [3H]inulin, [14C]sucrose, and fluorescein isothiocyanate dextran 20 compared with control tracheas. However, those tracheas exposed to 130 U peroxidase followed by 10(-5) M hydrogen peroxide showed an increased permeability to each of the three test solutes. We conclude that proteinase-free myeloperoxidase, in the presence of non-toxic concentrations of its substrates, hydrogen peroxide and halide, produced increases in permeability to non-ionic molecules in the rat trachea within 15 minutes.

PCR ribotyping and endonuclease subtyping in the epidemiology of Burkholderia cepacia infection.

Because of conflicting data about hospital-based transmission of Burkholderia (Pseudomonas) cepacia, an important respiratory pathogen in cystic fibrosis (CF), we compared strains found in sputum, lung, or blood of 29 CF patients in our center from 1988 to 1994, studying the relationship between strain and hospital exposure of incident and that of prevalent cases. Exposure was defined as a concurrent hospital stay between a prevalent and an incident case. B. cepacia strains were determined by polymerase chain reaction (PCR) ribotyping and endonuclease subtyping. The 16S to 23S spacer regions of the bacterial ribosomal RNA (rRNA) genes were amplified by PCR, and the product-size patterns used to type each B. cepacia isolate. Endonuclease digestion of the PCR products provided length polymorphisms for subtyping. There were 17 incident events during the period from 1988 to 1994, 16 of which involved a single ribotype. These 16 ribotypes could be divided into five subtypes by endonuclease mapping. Four patients grew B. cepacia from the blood, with the organism being the same strain as found in the lung in each case. Case controls were obtained to evaluate risk factors for B. cepacia acquisition. Concurrent hospitalization with a prevalent case significantly increased the risk of acquisition. There was no association between length of hospitalization, length of exposure, or FEV1 and the risk of B. cepacia acquisition.

Effect of eosinophil peroxidase on airway epithelial permeability in the guinea pig.

Increased numbers of eosinophils and increased concentrations of plasma proteins have been found in the airways of patients with mild asthma. We used an intact guinea pig trachea model to investigate the role of eosinophil peroxidase (EPO) in altering the function of the airway epithelial barrier. EPO in the presence of hydrogen peroxide (H(2)O(2)) and bromide (Br(-)) catalyzes the production of hypobromous acid (HOBr), which is felt to have a toxic effect on airway epithelial cells. An intact guinea pig trachea was mounted on an apparatus in a way that would allow the tracheal epithelium to be exposed to different solutions. Following these exposures, a test solution containing (14)C-sucrose (S), (3)H-inulin (I), and FITC-dextran-20 (D) was placed in the tracheal lumen and positioned in the center of the segment for 90 minutes. Flux of these molecules across the epithelial barrier into a bath was measured, and the permeability (P) was calculated for each molecule to quantify epithelial barrier function. Light and electron micrographic studies were performed to assess cellular damage. We found that there was a dose response to EPO (in the presence of fixed amounts of H(2)(O)(2) and Br(-)). EPO at 7.3 x 10(-7) M caused no increase in P over controls (Ringer's solution alone) for S, I, or D (P> 0.05), whereas EPO at 2.7 x 10(-6) M caused a significant increase in P over controls (P = 0.008) for all test molecules. Light and electron micrographs of the latter tracheas showed no evidence of microscopic changes despite the increased P. Further testing verified that the increase in permeability was caused by the EPO catalyzed reaction and not the individual substrates themselves, and that the reaction was inhibited by a peroxidase inhibitor. We conclude that EPO can alter the barrier function of the airway epithelium before gross cellular damage becomes visible. We hypothesize that changes in the tight junctions are responsible for the alteration in the barrier function of the airway epithelium and that this may play an important role in the pathophysiology of mild asthma.

Clinical significance of the recovery of Aspergillus species from the respiratory secretions of cystic fibrosis patients.

The frequent recovery of Aspergillus species from the respiratory tract secretions of cystic fibrosis (CF) patients is well recognized, and the presence of the fungus in the airways may trigger an inflammatory response that can manifest as the clinical entity known as allergic bronchopulmonary aspergillosis (ABPA). In our CF patient population we studied the clinical characteristics of those who had Aspergillus sp. recovered from their respiratory tract secretions (n = 45) and compared them with the characteristics seen, during the same time period, in those patients who were culture negative for Aspergillus sp. (n = 167). There were no differences in peripheral blood eosinophil count (P = 0.9) or serum immunoglobulin E levels (P = 0.61). By logistic regression analysis there seemed to be an increased risk for more advanced lung disease, both radiographically (defined by a Brasfield chest radiograph score < 18) and by lung function parameters in those who were culture positive. However, after appropriate adjustment, almost all the increased risk was associated with age and gender, but not with the presence of Aspergillus sp. in respiratory secretions. Additionally, increasing age was strongly correlated with the risk of Aspergillus sp. being cultured from respiratory secretions (P = 0.0025). The presence of Aspergillus sp. in respiratory secretions was not associated with two indicators of atopy in our CF patient population. We do not have evidence that the culture of Aspergillus sp. from CF respiratory secretions is independently associated with an increased risk for more advanced lung disease.

Sputum peroxidase activity correlates with the severity of lung disease in cystic fibrosis.

Patients with cystic fibrosis (CF) of the same age differ significantly in their degree of pulmonary disease. Based on preliminary observations, we postulated that the activity of myeloperoxidase would be significantly increased in patients with greater structural lung damage than in those with less lung damage. Acid extracts of weighed sputum samples were assayed for lactoferrin concentrations by ELISA. Activities of peroxidase, cathespsin G, and elastase (with and without proteinase 3) were determined by kinetic analysis using chromogenic substrates. The patients were divided into quartiles based on their Brasfield chest-radiograph score. Patients in the first quartile (least amount of structural lung abnormality) were compared to those in the fourth quartile. The concentration of lactoferrin, a specific (secondary) granule protein of neutrophils, did not differ between the two patient groups. However, the activities of the neutrophil primary granule proteins, peroxidase, elastase, and elastase plus proteinase 3, were significantly elevated in the group with the most structural lung abnormality. Sputum albumin concentration was used to estimate leakages of plasma proteins into the airways. Peroxidase activity, but not the activity of cathepsin G, of elastase, or of elastase plus proteinase 3, correlated significantly with albumin/g sputum in both quartile groups. To confirm the association of sputum peroxidase activity with differences in lung structure and to test its correlation with lung function, spirometry was performed in a second group of patients during the week prior to the time of sputum sampling. In this second group, increased sputum peroxidase activity was associated with worse Brasfield scores and with decreased percent-predicted forced expiratory volume in 1 sec.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnosing the cause of recurrent and persistent pneumonia in children.

It is very important to note that safe and effective treatment of recurrent or persistent pneumonia in children is based on firmly establishing an etiologic diagnosis. Empiric treatment using repeated courses of antibiotics and hope is unlikely to yield cure or even good control of most of these processes and is likely to result in more cost to the patient's health and pocketbook. Applied in a staged and systematic way, the diagnostic tools currently available should enable the clinician caring for children to diagnose most of their patients with recurrent or persistent pneumonia. Consultation with a pediatric pulmonologist will generally speed the process and help with difficult or confusing cases. Because effective therapy is available but differs greatly from one etiology to another, early accurate etiologic diagnosis is extremely important. The prognosis for those with asthma generally is very good. But, delay in diagnosis of other causes of recurrent or persistent pneumonia can lead to irreversible pulmonary structural damage that ultimately can only be treated by lung transplantation, if at all.

Prognostic implications of initial oropharyngeal bacterial flora in patients with cystic fibrosis diagnosed before the age of two years.

To evaluate the significance of early bacteriologic findings in infants and younger children with cystic fibrosis, we divided patients identified at < or = 2 years of age into groups by initial oropharyngeal culture: group NF, normal respiratory flora (n = 17); group SA, Staphylococcus aureus without Pseudomonas aeruginosa (n = 20); group PA, P. aeruginosa without S. aureus (n = 6); group PA/SA, P. aeruginosa and S. aureus (n = 7); and group O, other potentially pathogenic bacteria (n = 31). Follow-up of patients ranged in age from 5.4 to 13 years. At diagnosis, group PA/SA had lower Brasfield scores (p < 0.02) and higher gamma-globulin levels (p < 0.03) than the other groups. Five years after diagnosis, Brasfield scores were significantly lower in groups PA and PA/SA compared with the other groups; mean gamma-globulin levels did not differ significantly among the groups. Groups PA and PA/SA also had evidence of significantly greater obstructive pulmonary disease by spirometry than groups NF and O. Group PA/SA had a 10-year survival estimate of 57%, significantly lower than the 92% to 100% estimates of the other four groups (p < 0.0001). Thus P. aeruginosa in initial oropharyngeal cultures from patients < or = 2 years of age with cystic fibrosis was associated with significantly increased morbidity, and the finding of P. aeruginosa and S. aureus together in initial oropharyngeal cultures with a significantly increased mortality rate during the first 10 years after diagnosis.

Resolution of severe intrapulmonary shunting after liver transplantation.

A major complication of hepatic cirrhosis is arterial hypoxemia, often the result of intrapulmonary arteriovenous shunting. While previously such hypoxemia was thought to preclude successful hepatic transplantation, more recent studies have suggested that hepatic transplantation should be considered if the hypoxemia is corrected by supplemental oxygen. We report the findings in a cirrhotic patient with severe hypoxemia associated with intrapulmonary arteriovenous shunting. The patient did not respond to supplemental oxygen (PaO2 < 40 mm Hg on O2 at 4 L/min). The patient underwent successful hepatic transplantation, with complete resolution of intrapulmonary shunting. We believe that patients with cirrhosis-associated intrapulmonary shunting, even with hypoxemia resistant to supplemental oxygen, are acceptable candidates for hepatic transplantation.

Comparison of Tc-99m DTPA aerosol ventilation studies with pulmonary function testing in cystic fibrosis.

In 43 patients with cystic fibrosis, the results of 122 Tc-99m DTPA aerosol ventilation (DAV) studies were compared with pulmonary function tests (PFTs) that were performed within 24 hours of the DAV studies. The DAV studies were evaluated blindly for (A) number of pulmonary segments showing little or no ventilation, (B) number of foci of bronchial deposition of aerosol, and (C) subjective overall improvement, lack of change, or worsening from the previous study. (A) and (B) correlated significantly with all PFTs (p's < .001, r's = -.51 to -.73). Changes in (A) and (B) also correlated with changes in PFTs (p's < or = .001, r's = -.37 to -.58). The three populations in (C) were significantly different from each other with respect to changes in all PFTs (p < or = .002). Intervals between studies showing subjective improvement, no change, and worsening averaged 60, 133, and 306 days, respectively. These results suggest that DAV is an indicator of both regional and global pulmonary function and may be useful in evaluating patients with cystic fibrosis.

Aerosol scintigraphy in the assessment of therapy for cystic fibrosis.

Thirteen patients with cystic fibrosis (aged 11 to 32 years) who were hospitalized for exacerbation and who had sputum cultures positive for Pseudomonas organisms were treated initially for 4 days with bronchodilators and physiotherapy followed by the addition of antibiotic (14 days, n = 8) or placebo (14 days, n = 4; 7 days, n = 1). Tc-99m DTPA aerosol scintigraphy was performed on the day before bronchodilators and physiotherapy, on the day before antibiotic or placebo, and on the day after completion of antibiotic or placebo therapy. Scintigrams were evaluated for change in the number of nonventilated segments and change in the number of bronchial deposits of aerosol. Sixty-nine percent of patients showed improvement after bronchodilators and physiotherapy alone. Sixty-two percent showed further improvement after antibiotic or placebo was added; this improvement was independent of whether antibiotic or placebo was administered (P greater than 0.1). These aerosol scintigraphy results failed to demonstrate that the effectiveness of bronchodilators and physiotherapy is enhanced by antibiotics in the treatment of cystic fibrosis exacerbations.

The association of pauciarticular juvenile arthritis and myasthenia gravis.

We encountered two children with fluorescent antinuclear antibody-positive pauciarticular juvenile arthritis who later developed myasthenia gravis. Acetylcholine receptor binding, blocking, and modulating antibodies, retrospectively tested on frozen serum, yielded negative results before the onset of myasthenic symptoms but all yielded strongly positive results coincident with the onset of weakness. In both children, myasthenia gravis responded to thymectomy, and one child had a beneficial response to plasmapheresis. Although, to our knowledge, only two patients with juvenile arthritis and myasthenia gravis have been described in the past, the presence of two additional children with both diseases in a single clinic population suggests that the association may be more prevalent than previously suspected.

Increased monocyte oxidase activity in cystic fibrosis heterozygotes and homozygotes.

Freshly isolated monocytes from cystic fibrosis (CF) heterozygotes and homozygotes had significantly increased oxygen uptake and superoxide formation after surface glycoprotein stimulation than did monocytes from age- and sex-matched controls. Lack of differences among the genotypes in inhibition by simple sugars of the concanavalin A-stimulated superoxide production and lack of differences in concanavalin A-binding surface proteins suggested that different regulation of the oxidase pathway produced the increased oxygen uptake and superoxide formation in CF patients and carriers. This regulatory role is consistent with the predicted structure of the CF gene product. The results support the hypothesis that the mononuclear phagocytes of CF heterozygotes have a significantly increased ability to kill intracellular microbes and may confer a selective advantage to the host.

Pseudomonas aeruginosa variants isolated from patients with cystic fibrosis are killed by a bactericidal protein from human polymorphonuclear leukocytes.

The susceptibility of paired mucoid and nonmucoid variants of Pseudomonas aeruginosa isolated from 13 patients with cystic fibrosis (CF) to killing by a 55,000-Da bactericidal protein (BP55) from human polymorphonuclear leukocytes was studied. Mucoid and nonmucoid variants were equally sensitive to killing by BP55 at both pH 5.6 and pH 7.2. Eleven of the isolates were resistant to the bactericidal activity of 10% normal human serum but were as sensitive as the serum-sensitive isolates to BP55. Similarly, the 15 isolates with lipopolysaccharides (LPS) containing O-polysaccharide side chains (smooth LPS) were as sensitive to BP55 as those isolates with rough LPS.P. aeruginosa isolates from patients in poor clinical condition were more likely to have LPS of the smooth type and to be resistant to killing by 10% human serum than the isolates from patients in good clinical condition. We have concluded that the susceptibility of the P. aeruginosa isolates from patients with CF to killing by BP55 does not correlate with mucoid or nonmucoid variations, with the presence or absence of smooth LPS, or with the sensitivity or resistance to killing by normal human serum.

Reduction of sputum Pseudomonas aeruginosa density by antibiotics improves lung function in cystic fibrosis more than do bronchodilators and chest physiotherapy alone.

We evaluated patients with cystic fibrosis (CF) and moderate obstructive lung disease in pulmonary exacerbation in a double-blind placebo-controlled trial to determine the contribution of antibiotic-mediated reduction in sputum bacterial density to clinical improvement. For the first 4 days of study, all patients received bronchodilating aerosols and chest physiotherapy but no antibiotics. During this time, the patients showed significant improvement in mean FVC, FEV1, and maximal midexpiratory flow rate (FEF25-75). In 12 of 13 trials, the patients showed no significant increases in the density of Pseudomonas aeruginosa during these first 4 days. In these 12 trials, the patients were stratified by their initial FVC and randomized to receive either parenteral tobramycin and ticarcillin (n = 7) or placebo (n = 5), in addition to continued aerosol and chest physiotherapy. In the remaining trial, the patient had a significant rise in the density of P. aeruginosa and was assigned to the antibiotic group. During the next 14 days of therapy, the antibiotic group showed significantly (p less than 0.01) greater reductions in log10 colony-forming units (cfu) of P. aeruginosa per gram of sputum and greater increases in FVC, FEV1, and FEF25-75 than did the placebo group. The degree of decrease in log10 cfu P. aeruginosa/g sputum correlated significantly (p less than 0.001) with the degree of improvement in FVC, FEV1, and FEF25-75.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytokines and immunoglobulin in rheumatic heart disease: production by blood and tonsillar mononuclear cells.

Rheumatic fever and rheumatic heart disease are considered to result from abnormal immune responses after Group A streptococcal pharyngitis. Production of interleukin 1 (IL-1), tumor necrosis factor-alpha (TNF), interleukin 2 (IL-2) and immunoglobulin (Ig) by blood and tonsillar mononuclear cells from rheumatic or healthy children was measured after stimulation in vitro by pokeweed mitogen (PWM) or the streptococcal extracellular product, blastogen A (BLA). Tonsillar cells from patients with rheumatic heart disease produced significantly less IL-1, TNF, IL-2, and Ig than control tonsillar cells. In contrast, blood mononuclear cell cultures from rheumatic children produced more TNF and IL-2 than controls. Our findings suggest that abnormal regulation of cytokine and Ig production may contribute to the pathogenesis of acute rheumatic fever and rheumatic heart disease.

Lyme disease in children.

Lyme disease is an increasing health risk for children. Pediatricians should become familiar with the different clinical syndromes caused by the Borrelia burgdorferi. Appropriate antibiotic therapy must be initiated and follow-up of these children should be a part of the management as some may develop (tertiary) chronic borreliosis. Lyme disease should be considered in the diagnostic work-up of heart block, childhood arthritis and in undiagnosed peripheral and central nervous system disease. Serologic tests appear to be quite specific and sensitive in children with late stage disease in our experience. Newer diagnostic tests to detect infection during the early stage will optimize the management of Lyme disease and further decrease the incidence of long-term sequelae.

Distribution of cells bearing "rheumatic" antigens in peripheral blood of patients with rheumatic fever/rheumatic heart disease.

Cell surfaces of some peripheral blood cells from individuals with a history of rheumatic fever/rheumatic heart disease (RHD) have been demonstrated by the use of monoclonal antibodies to be antigenically distinct from the majority of the population. Our study examines the distribution of cells bearing these "rheumatic" antigens in 23 subjects with rheumatic fever/RHD of Maori, Polynesian and Caucasian ancestry and 182 members of their families (rheumatic fever/RHD families) as well as in 46 members of families in which no member had been demonstrated to have had rheumatic fever/RHD (control families). Mononuclear cells from the blood of all cooperating family members were prepared and non-T cells isolated by sheep red blood cell rosette depletion. The binding of monoclonal antibodies 83S19.23 and D8103 to non-T cells was measured using an immunoperoxidase technique. Subjects with rheumatic fever/RHD had a significantly higher proportion of cells binding the antibodies than the unaffected members of all families. Unaffected members of rheumatic fever/RHD families had significantly higher levels of such rheumatic cells than control families. An increase in the proportion of rheumatic cells with age was noted in unaffected members of rheumatic fever/RHD families but not in rheumatic fever/RHD subjects of control families. A level of 13% 83S19.23 positive non-T cells optimally discriminated between rheumatic and nonrheumatic individuals. The relative risk for rheumatic fever/RHD with 13% or greater positive cells was 9.48. The negative predictive value of having less than 13% positive cells was 98.3%. In the population studied, 83S19.23 seems especially capable of identifying those with low risk for rheumatic fever/RHD.