Anti‐neutrophil cytoplasmic antibodies directed against the bactericidal/permeability‐increasing protein (BPI) in pediatric cystic fibrosis patients do not recognize N‐terminal regions important for the anti‐microbial and lipopolysaccharide‐binding activity of BPI

This study was performed to examine the prevalence and clinical correlates of bactericidal/permeability‐increasing protein anti‐neutrophil cytoplasmic antibodies (BPI‐ANCA) in pediatric cystic fibrosis (CF) patients and to elucidate their possible role in CF pulmonary pathology. Sera of 27 CF patients were tested for ANCA by indirect immunofluorescence (IFT) and by enzyme‐linked immunosorbent assay (ELISA) for ANCA sub‐specificities. BPI‐ANCA were examined by using standard ELISA for BPI, lipopolysaccharide‐binding protein (LBP), and BPI/LBP fusion proteins to epitope map the main binding sites and look for cross‐reactivity with LBP. Pulmonary function and serum concentrations of total immunoglobulin G (IgG) were measured and infections were diagnosed. In addition, release of reactive oxygen species (ROS) by neutrophil granulocytes was measured after stimulation with monoclonal BPI‐ANCA. Using IFT, two patients showed atypical ANCA staining, six patients exhibited perinuclear ANCA staining, and no cytoplasmic ANCA staining was detected. Of 27 patients, 13 (48%) were BPI‐ANCA (IgG) positive, and three were also immunoglobulin A (IgA) BPI‐ANCA positive; one patient had ANCA against lactoferrin; and no proteinase 3 ANCA was detected in any of the patients. All BPI‐ANCA bound to the C‐terminal region of the molecule; none bound to the N‐terminus or to LBP. There was no significant correlation between clinical data and the occurence of BPI‐ANCA in this cross‐sectional study. Release of ROS from granulocytes was induced by monoclonal BPI‐ANCA. Activation of neutrophils and possible modulation of BPI‐mediated opsonophagocytosis and disposal of Gram‐negative bacteria and lipopolysaccharides by BPI‐ANCA raise the possibility that they contribute to pulmonary pathology in pediatric CF patients but intervention longitudinal studies in large groups of patients are needed to establish a causative association.     

Maintenance azithromycin treatment in pediatric patients with cystic fibrosis: long-term outcomes related to macrolide resistance and pulmonary function

BACKGROUND: Maintenance azithromycin therapy may improve pulmonary function in patients with cystic fibrosis (CF) with Pseudomonas aeruginosa infection because of its antiinflammatory properties. However, azithromycin therapy might increase macrolide resistance in Staphylococcus aureus cultured from respiratory secretions. We studied the emergence of macrolide resistance in S. aureus and correlated this to pulmonary function decline in pediatric patients with CF on daily azithromycin therapy. METHODS: Respiratory cultures of 100 patients with CF were analyzed for S. aureus colonization and its resistance pattern before and during 3 years after initiation of azithromycin maintenance therapy. Mean annual change in forced expiratory volume as percent of predicted (FEV1 %) was calculated to compare pulmonary function before and after azithromycin therapy. RESULTS: Staphylococcal colonization did not significantly decrease after initiation of azithromycin (50% versus 48%). Before start of therapy, 10% of patients with staphylococcal colonization had macrolide-resistant strains. Staphylococcal resistance increased to 83% in the first year; 97% in the second and 100% in the third year after initiation of azithromycin therapy (P < 0.001). Half of macrolide-resistant S. aureus comprised the macrolide-lincosamide-streptogramin phenotype. Percent forced expiratory volume in 1 second improved in the first year after initiation of azithromycin (mean annual change: -4.75% before versus +3.09% after initiation; P < 0.01) but decreased during the second and third years after initiation (-5.15% and -3.65%, respectively). Emergence of macrolide-resistant S. aureus was not related to pulmonary function decline. CONCLUSION: Maintenance azithromycin therapy in patients with CF leads to macrolide resistance in nearly all S. aureus carriers. Pulmonary function improvement after initiation of azithromycin therapy seems to be temporary and appears not to be related to macrolide resistance of S. aureus.     

Risk factors for Pseudomonas aeruginosa colonization in cystic fibrosis patients

In an attempt to study the association between Pseudomonas aeruginosa colonization and clinical factors present before colonization, we studied 502 patients who attended our cystic fibrosis (CF) clinic between 1975 and 1988 and who were not colonized with P. aeruginosa before the study period. Twelve percent of the patients became colonized with P. aeruginosa before the age of 1 year and 44% by the age of 7 years. In a birth cohort followed from diagnosis during the study period, 23% were colonized with P. aeruginosa before age 1 year and 67% before age 7 years. Early P. aeruginosa colonization was associated with early diagnosis of CF. Presence of meconium ileus, gastrointestinal symptoms and pancreatic insufficiency at the time of diagnosis was also associated with early colonization. There was no association between the presence of respiratory symptoms at the time of diagnosis and age at first P. aeruginosa colonization. In families in which more than one sibling had CF, the age of P. aeruginosa acquisition was similar in the first colonized and the subsequently colonized siblings. In the year before the colonization patients with P. aeruginosa who were older than 1 year had higher rates of hospitalization and spent more days in hospital compared with patients without P. aeruginosa. In conclusion most P. aeruginosa colonization occurs at a younger age than previously reported. Early age at diagnosis and presence of CF-associated gastrointestinal abnormalities increase the likelihood of earlier colonization of P. aeruginosa.     

Association between serum oncofetal antigens CA 19-9 and CA 125 and clinical status in patients with cystic fibrosis

In cystic fibrosis (CF), mucus plugging in the airways and in the gastrointestinal tract leads to severe morbidity and mortality. The mucin-associated antigens CA 19-9 and CA 125 are markers of gastrointestinal malignancy, and CA 19-9 has also been reported in association with pulmonary function in CF. Aim: To test whether these antigens might serve as markers for the severity of pulmonary and gastrointestinal disease in CF. Methods: In 99 patients, aged 1 to 48 y, serum levels of CA 19-9 and CA 125 were measured by RIA and ELISA and related to clinical data. Results: Patients with severe mutations had significantly increased serum levels of CA 125, indicating an association with a more severe CF phenotype. This was further supported by the association with lung function, chronic pulmonary colonization of Pseudomonas aeruginosa and pancreatic insufficiency. CA 19-9 was also shown to be associated with lung function and Ps. aeruginosa colonization. No gastrointestinal malignancy was found in our patients despite very high values of CA19-9 in some patients. During a 5-y follow-up, the very high serum levels of CA 19-9 decreased along with improved general condition of the patients.

Conclusion: Increased serum levels of CA 125 in CF patients were associated with severe cystic fibrosis transmembrane conductance regulator mutations and a severe phenotype. Both antigens were associated with pseudomonas colonization and lung function and CA 125 also with pancreatic insufficiency. The estimates of CA 19-9 are hampered by the influence of the Lewis histo-blood group system on the synthesis of CA 19-9.     

Differences in resting energy expenditure between male and female children with cystic fibrosis

OBJECTIVES: To evaluate which factors might contribute to raised resting energy expenditure (REE) in patients with cystic fibrosis (CF). STUDY DESIGN: REE and anthropometry were measured in 134 (males = 68) children with CF and 100 (males = 51) controls (range, 3-18.7 years) in an outpatient setting. Bacterial colonization, liver disease, inhaled steroid use, pancreatic and pulmonary function, sex, and genotype were determined and regression analysis was used to determine the predictors of REE in the group with CF. RESULTS: REE for children with CF was increased on average by 7.2% compared with controls. This increase was greater for females than for males. REE in males was positively associated with fat-free mass (FFM), pancreatic insufficiency (PI), and liver disease, and negatively associated with pulmonary function, whereas in females, REE was positively associated with FFM and PI. REE (adjusted for FFM) was higher in children with a severe mutation (5495 +/- 47 kJ) compared with a mild mutation (5,176 +/- 124 kJ, P <.02). CONCLUSIONS: PI, severe mutations, and female sex are the main contributing factors to elevated REE in patients with CF with near normal pulmonary function.     

Pulmonary function and clinical course in patients with cystic fibrosis after pulmonary colonization with Pseudomonas aeruginosa

To evaluate the relationship between Pseudomonas aeruginosa colonization and the development of lung disease, we studied 895 patients who attended our cystic fibrosis clinic between 1975 and 1988. The prevalence of P. aeruginosa colonization was 82%. Patients who acquired P. aeruginosa in the first year of life had a similar 10-year survival rate (85%) to that in patients who were colonized between the ages of 1 and 7 years (87%), and to that in patients colonized after the age of 7 years (78%). One year before colonization, mean age, forced expiratory volume in 1 second (FEV1), forced vital capacity, and forced expiratory flow in the mid-expiratory phase were similar to those in a group of patients who remained free of P. aeruginosa. No significant change in pulmonary function variables could be demonstrated 1 year and 2 years after the colonization. The rate and duration of hospitalization did not increase in the years after P. aeruginosa colonization compared with the years before colonization. By the age of 7 years, the mean percentage of predicted FEV1 was lower by 10% in patients who were already colonized by P. aeruginosa compared with those who were not colonized (p less than 0.01). A similar reduction in FEV1 was observed at all ages from 7 to 35 years, but no precipitate rate of decline in FEV1 could be associated with P. aeruginosa colonization. We conclude that although P. aeruginosa colonization is associated with 10% lower lung function, it does not cause an immediate and rapid reduction, as has been previously reported. The clinical course and the pulmonary deterioration in cystic fibrosis after P. aeruginosa colonization is a gradual and variable process.     

Serotype-specific serum IgG antibodies to lipopolysaccharides of Pseudomonas aeruginosa in cystic fibrosis: correlation to disease, subclass distribution, and experimental protective capacity

Various studies have demonstrated pronounced systemic IgG response to Pseudomonas aeruginosa (PA) infection in cystic fibrosis (CF). However, antibody response to serotype-specific lipopolysaccharides (LPS) has never been studied. ELISA for detection of IgG antibodies to LPS of nine PA-serotypes and to toxin A were performed with serum of 78 CF patients. Anti-LPS profiles of antibodies were confirmed by SDS-PAGE and immunoblotting techniques. The most frequent PA-serotypes found were immunotypes (IT) IT-1 and IT-2, and Habs-3 and Habs-4. Ten patients without PA colonization showed no detectable antibody titers. In patients with chronic PA colonization (n = 46), these antibody titers were significantly (p less than 0.005) higher than in patients with intermittent PA colonization (n = 22). Mean serum antibody titers to LPS of PA IT-1, IT-2, Habs-3, and Habs-4 correlated with duration of PA colonization and with disease severity. Subclass analysis of anti-LPS antibodies revealed elevated levels for all four IgG subclasses and for IgA1. The IgG antibodies to LPS of PA proved to be protective in a murine burn wound sepsis model. We conclude that anti-LPS antibodies to specific PA serotypes in serum may be a sensitive measure of severity and prognosis of CF. Patients with CF show adequate functional immune response to LPS of PA, and it is possible that vaccination against PA before colonization could induce protective immunity.     

Burkholderia cepacia in cystic fibrosis: novel Australian cluster strain without accelerated respiratory deterioration

OBJECTIVE: To determine whether 4 years of colonization with a novel Australian cluster strain (The 'Hunter' strain) of Burkholderia cepacia (B. cepacia) in cystic fibrosis (CF) patients was associated with more rapid decline in nutritional status and pulmonary function than in non-colonized contemporaries from the same CF clinic. METHODOLOGY: A retrospective review of respiratory function and nutritional data from a single multidisciplinary paediatric CF clinic over 4 years (1993-97). RESULTS: Paired spirometry data for 1993 and 1997 were available in 47 patients without (n = 31) and with B. cepacia (n = 16) colonization (mean (+/- SD) ages in 1993: 12.1 years +/- 4.0 vs 12.6 years +/- 6.5; P = 0.83). Their percentage predicted forced expiratory volume in 1 s (FEV1) (94.2% +/- 16.7 vs 85.9% +/- 21.2; P = 0.19) were not significantly different. The averaged annual fall in FEV1 over 4 years was also not significantly different (3.8% +/- 3.8 vs 3.6% +/- 3.7; P = 0.82). Weight percentile (Wt%), height percentile (Ht%) and percentage age weight for height (%WFH) were not significantly different between groups in 1993. By 1997, Wt% (36.7% +/- 25.1 vs 22.3% +/- 19.6; P = 0.04) and Ht% (42.5% +/- 29.6 vs 17.6% +/- 19.4; P = 0.002) but not %WFH (102% +/- 10.0 vs 106% +/- 11.2; P > 0.10) were lower in subjects with B. cepacia. CONCLUSIONS: In adolescent CF patients, colonization with the Hunter strain of B. cepacia was associated with a deterioration in some nutritional parameters but not with an accelerated decline in FEV1 over 4 years. As varying pathogenicity of B. cepacia strains may account for differing rates of pulmonary decline, further assessment of the consequences of colonization with certain strains of B. cepacia in CF is needed.     

Antibiotic prophylaxis in infants and young children with cystic fibrosis: a randomized controlled trial

OBJECTIVES: To evaluate whether antistaphylococcal prophylaxis in infants and young children with cystic fibrosis (CF) would suppress the acquisition of Staphylococcus aureus and delay the onset of the manifestations of bronchopulmonary disease. STUDY DESIGN: A 7-year, multicenter, double-blind, placebo-controlled study of continuous antistaphylococcal therapy. Otherwise healthy children <2 years of age with CF were randomly assigned to be treated with daily cephalexin (80-100 mg/kg/day) or placebo. Clinical, microbiologic, laboratory, radiographic, and anthropometric outcomes were evaluated. RESULTS: Of 209 children enrolled, 119 completed a 5- to 7-year course of therapy. Mean age at enrollment was 15.6 and 14.1 months in the cephalexin and placebo groups, respectively. Respiratory cultures from children treated with cephalexin were significantly less likely to be positive for S aureus (6.0% vs 30.4%; P <.001). They were, however, much more likely to be positive for Pseudomonas aeruginosa (25.6% vs 13.5%; P <.009). These differences became apparent in the first year after enrollment and persisted over the duration of the study. In contrast to these microbiologic differences, there were no differences in clinical outcome measures, including radiographic (Brasfield score, 23.4 vs 23.2) or anthropometric scores or pulmonary function. CONCLUSIONS: Although long-term prophylaxis with cephalexin successfully delayed the acquisition of S aureus, it enhanced colonization with P aeruginosa and did not lead to clinically significant improvement in major health outcomes. These data do not support routine antistaphylococcal prophylaxisin otherwise healthy infants and young children with CF.     

Relative increase in IgG antibodies to Pseudomonas aeruginosa 60-kDa GroEL in prediabetic patients with cystic fibrosis

In recent years research has focused on a possible connection between bacterial infection and development of diabetes mellitus. In this study, serum antibody responses against bacterial antigens in diabetic and nondiabetic patients with cystic fibrosis (CF) were evaluated. The first part of the study included 252 CF patients of whom 46 (18 %) had diabetes. This study showed that precipitating antibodies (precipitins) against Pseudomonas aeruginosa and other bacteria in crossed immunoelectrophoresis, and IgG antibodies against a 60-kD GroEL of P. aeruginosa, were highly variable and positively correlated with age. Patient material matched for age and sex showed no significant difference between diabetic and nondiabetic CF patients in precipitins or IgG antibodies to P. aeruginosa GroEL. Two longitudinal studies of 9 and 5 y using retrospectively selected sera from 29 prediabetic and 29 cross-matched nondiabetic CF patients were performed. As to precipitins against P. aeruginosa, we found no difference between the prediabetic and the nondiabetic group of patients during the study period. The study revealed, however, a significant increase of 24.6 % (p = 0.008) of IgG antibodies against P. aeruginosa 60-kD GroEL, 3-12 mo before the onset of diabetes in patients with CF, compared with an overall increase of 5 % to 6 % per year in both groups during the observation period. This study shows that diabetes in CF appears after a peak of serum IgG antibodies against GroEL and indicates that development of diabetes in CF patients may not only be caused by a progressive fibrosis of the pancreatic tissue, but may be augmented by a short-term specific immunologic reaction, initially triggered by an ongoing and progressive pulmonary infection.     

Clinical outcome after early Pseudomonas aeruginosa infection in cystic fibrosis

OBJECTIVE: To determine the clinical consequences of acquiring Pseudomonas aeruginosa infection during early childhood in children with cystic fibrosis (CF). DESIGN: Prospective, observational cohort study of 56 children with CF identified by newborn screening during 1990-92. Each child underwent an annual bronchial lavage during the first 2 to 3 years of life. Clinical outcome was determined at 7 years of age. RESULTS: P aeruginosa infection was diagnosed in 24 (43%) cohort subjects. Four children died before 7 years of age, all of whom had been infected with a multi-resistant, mucoid strain of P aeruginosa (P =.04). In survivors, P aeruginosa infection was associated with significantly increased morbidity as measured by lower National Institutes of Health scores, greater variability in lung function, increased time in the hospital, and higher rates of recombinant human deoxyribonuclease therapy (P <.01). In this young CF cohort, best forced expiratory volume in 1 second was an insensitive measure of increased morbidity. CONCLUSIONS: Acquisition of P aeruginosa was common by 7 years of age in this CF birth cohort and was associated with increased morbidity and mortality. An improved disease severity score would improve the evaluation and study of early CF lung disease.     

Pseudomonas-infected cystic fibrosis patient sputum inhibits the bactericidal activity of normal human serum

Sputum samples were obtained from nineteen cystic fibrosis (CF) patients with respiratory tract infections due to Pseudomonas aeruginosa and were examined for the presence of a specific local protective or blocking factor, which might partially explain the inability of CF patients' pulmonary defense mechanisms to clear their lungs of Pseudomonas infection. Using an assay that measures the bactericidal activity of fresh normal human serum (FHS), eighteen of nineteen CF sputa examined were capable of protecting either autologous or heterologous strains of P. aeruginosa from serum bactericidal activity. Most of this protective activity was absorbable at 4 degrees C by Pseudomonas, and could be reduced by dilution in phosphate buffered saline or counteracted by an increase in serum concentration. This protective activity is believed to be due to a Pseudomonas-specific bactericidal blocking antibody. In contrast, only two of 17 non-CF sputa were found to significantly inhibit the bactericidaL activity of FHS for P. aeruginosa. Furthermore, three out of five CF sputa also protected Escherichia coli from the bactericidal activity of FHS. This protective activity was much less than that observed with P. aeruginosa, and was not absorbable at 4 degrees C, suggesting the presence of a second blocking or protective factor in CF sputum. From these observations, we conclude that sputum from CF patients infected with P. aeruginosa contains one or more factors that interfere with the bactericidal activity present in FHS.     

Occurrence of nonfermentative gram-negative rods other than Pseudomonas aeruginosa in the respiratory tract of children with cystic fibrosis

There have been no comprehensive microbiologic studies of the frequency of respiratory colonization with nonfermentative gram-negative rods (NFGNR) other than Pseudomonas aeruginosa in patients with cystic fibrosis (CF). Records of bacteria isolated from throats and sputa of CF patients of the Yale-New Haven Hospital CF Clinic from 1975-1979 were reviewed in order to determine the incidence of these species. Thirty-one strains were recovered. Twenty patients from the CF Clinic (with an average census of 170 patients) yielded at least one isolate of non-P. aeruginosa NFGNR, and eight of them showed more than one species on at least one occasion. Two patients also carried P. aeruginosa and ten carried Staphylococcus aureus on at least one occasion. Using a standardized method of clinical scoring, our patients had a course not unlike our general CF population.     

Serum hyaluronic acid concentrations are increased in cystic fibrosis patients with liver disease.

AIM: To determine whether serum hyaluronic acid (HA) concentrations are abnormal in patients with cystic fibrosis (CF) liver disease, and if so, whether the abnormality is associated with disease severity. METHODS: A total of 74 patients with CF were assessed for evidence of liver involvement as indicated by clinical, ultrasound, and biochemical findings. Serum hyaluronic acid concentrations were measured and compared with concentrations in 293 normal controls. Lung function in the CF patients was also recorded. RESULTS: Thirty four CF patients had no evidence of liver disease; in these, serum HA concentrations were similar to those in healthy controls (median (range): 16.1 (9.4-75.1) v 15 (1-77) microg/l). Nineteen CF patients had established liver disease detected by clinical and ultrasound examination, with significantly increased HA concentrations (56.1 (26-355) microg/l). Serum HA concentrations were also significantly increased, although to a lesser extent, in 21 CF patients with an abnormal liver ultrasound scan alone (22.4 (9.5-43.4) microg/l). There was no correlation between serum HA concentration and lung function. CONCLUSION: Serum HA concentrations were significantly increased in children with clinical or ultrasound evidence of liver disease, being higher in those with more advanced hepatic damage. Despite the inflammation and fibrosis present in CF lungs there was no correlation between HA concentration and lung function, suggesting that high concentrations were a failure of hepatic clearance rather than overproduction in the lung. Longitudinal measurement of HA concentrations may prove a useful marker for the development of significant liver damage in CF patients.     

Pseudomonas cepacia colonization in patients with cystic fibrosis: risk factors and clinical outcome

During the period of 1979 to 1983, 38 patients with cystic fibrosis (CF) at the CF center of St. Christopher's Hospital for Children in Pennsylvania developed respiratory tract colonization with Pseudomonas cepacia. Seventeen (45%) of the patients with colonization died. Yearly incidence rates of P. cepacia colonization fluctuated between 1.3% and 6.1%, suggesting an endemic phenomenon. Case-control studies showed that severe underlying CF, use of aminoglycosides, and having a sibling with CF and P. cepacia colonization were significant risk factors for P. cepacia colonization. Once colonized with P. cepacia, patients with CF were likely to be hospitalized longer (P = 0.008) and to die sooner (P = 0.0001) than control patients with CF. Environmental and microbiologic studies did not identify a common source or mode of transmission of P. cepacia among patients. The results of this investigation suggest that P. cepacia colonization of patients with CF was endemic in the hospital, occurred more frequently in those with severe disease, and was associated with adverse clinical outcome.     

Serum hyaluronic acid concentrations are increased in cystic fibrosis patients with liver disease

Aim: To determine whether serum hyaluronic acid (HA) concentrations are abnormal in patients with cystic fibrosis (CF) liver disease, and if so, whether the abnormality is associated with disease severity. Methods: A total of 74 patients with CF were assessed for evidence of liver involvement as indicated by clinical, ultrasound, and biochemical findings. Serum hyaluronic acid concentrations were measured and compared with concentrations in 293 normal controls. Lung function in the CF patients was also recorded. Results: Thirty four CF patients had no evidence of liver disease; in these, serum HA concentrations were similar to those in healthy controls (median (range): 16.1 (9.4–75.1) v 15 (1–77) µg/l). Nineteen CF patients had established liver disease detected by clinical and ultrasound examination, with significantly increased HA concentrations (56.1 (26–355) µg/l). Serum HA concentrations were also significantly increased, although to a lesser extent, in 21 CF patients with an abnormal liver ultrasound scan alone (22.4 (9.5–43.4) µg/l). There was no correlation between serum HA concentration and lung function. Conclusion: Serum HA concentrations were significantly increased in children with clinical or ultrasound evidence of liver disease, being higher in those with more advanced hepatic damage. Despite the inflammation and fibrosis present in CF lungs there was no correlation between HA concentration and lung function, suggesting that high concentrations were a failure of hepatic clearance rather than overproduction in the lung. Longitudinal measurement of HA concentrations may prove a useful marker for the development of significant liver damage in CF patients.     

Early bacteriologic, immunologic, and clinical courses of young infants with cystic fibrosis identified by neonatal screening

To understand better the events associated with the initiation of lung disease in young children with cystic fibrosis (CF), we prospectively performed a longitudinal study examining the early bacteriologic, immunologic, and clinical courses of 42 children with CF diagnosed after identification by neonatal screening. Serial evaluations included history and physical examination, chest radiographs, throat cultures for bacteria, and determinations of serum immunoglobulin levels and circulating immune complexes. At a mean follow-up age of 27 months, 19% of the children had serial throat cultures positive for Pseudomonas aeruginosa; the first positive culture was found at a mean age of 21 months. In three infants the initial P. aeruginosa isolates were mucoid. As determined by typing with a DNA probe, serial P. aeruginosa isolates from each patient were identical over time but were genetically distinct from isolates recovered from other patients. Of 11 infants with P. aeruginosa, nine (82%) had previous isolates of Staphylococcus aureus or Haemophilus influenzae; all had received prior antibiotic therapy. In comparison with other infants with CF, children with P. aeruginosa grown on serial throat cultures more frequently had daily cough (p less than 0.01), lower chest radiograph scores (p less than 0.05), and elevated levels of circulating immune complexes (p less than 0.01). None of the study infants had persistent hypogammaglobulinemia or hypergammaglobulinemia. We conclude that (1) S. aureus and H. influenzae remain the isolates most frequently recovered from infants with CF; (2) initial recovery of P. aeruginosa by throat culture is often preceded by the onset of chronic respiratory signs; (3) elevations of circulating immune complexes can occur early, often after the initial recovery of P. aeruginosa; and (4) early P. aeruginosa isolates are genetically distinct, demonstrating the lack of cross-colonization in this newborn population.     

Pseudomonas aeruginosa chronic colonization in cystic fibrosis patients

PURPOSE OF REVIEW: Chronic infection with Pseudomonas aeruginosa is a leading cause of morbidity and mortality in individuals with cystic fibrosis despite the aggressive use of antibiotics. P. aeruginosa employs a number of strategies that promote chronic pulmonary colonization instead of acute infection. These include biofilm formation, evasion of the host immune system, and conversion to a mucoid phenotype. This review discusses recent advances regarding P. aeruginosa pathogenesis and biofilm behavior in the setting of chronic pulmonary disease. RECENT FINDINGS: Biofilm formation in the cystic fibrosis lung likely occurs under anaerobic conditions, is controlled by bacterial quorum-sensing mechanisms, and is enhanced by environmental components in the cystic fibrosis airway. P. aeruginosa possesses regulatory pathways that recognize environmental cues to favor either acute infection or chronic colonization. P. aeruginosa that inhabit the respiratory tract accumulate mutations favoring chronic colonization. Azithromycin, a macrolide with clinical benefit in cystic fibrosis, alters P. aeruginosa biofilm formation. Promising new therapies that target biofilm formation include molecules that disrupt quorum sensing. SUMMARY: Eradication of P. aeruginosa in cystic fibrosis patients remains problematic. As more information emerges about P. aeruginosa behavior in vivo, potential therapeutics directed against biofilms and mucoid P. aeruginosa are being developed.     

Altered antibody isotype in cystic fibrosis: possible role in opsonic deficiency

Patients with cystic fibrosis (CF) whose respiratory tracts are colonized with Pseudomonas aeruginosa (PA) may develop a specific opsonic deficiency for alveolar macrophage phagocytosis of PA. We examined the possible role of altered antibody (Ab) isotype in this phenomenon by measuring serum levels and distribution of IgG and IgG subclass Ab (IgG1, IgG2, IgG3, and IgG4) to the major opsonic immunodeterminant, serotype-specific lipopolysaccharide (LPS), by means of enzyme-linked immunosorbent assays employing monoclonal secondary antibodies, and comparing these results to the serum opsonic capacity in an in vitro murine alveolar macrophage phagocytic assay. Twenty-one patients with CF who were colonized with PA had approximately a 30-fold elevation of PA LPS IgG Ab levels and higher IgG subclass 1-4 Ab compared to 10 uncolonized patients with CF and 11 healthy controls (p less than 0.05-0.0005 depending on the isotype). Colonized patients with CF had a shift in PA LPS Ab distribution toward IgG3 compared to uncolonized patients with CF (p less than 0.02). A surprising finding was that uncolonized patients with CF had lower levels (p less than 0.05) and proportion (p less than 0.002) of PA LPS IgG2 Ab than controls, with an apparent shift to higher levels and proportion of PA LPS IgG4 (p less than 0.01). Serum from colonized patients with CF showed diminished opsonic capacity for phagocytosis of PA compared to uncolonized patients and controls (p less than 0.005), with 42% showing inhibitory activity. Functional Ab was also found to be inhibitory at high (greater than 500 ng/ml) concentrations. Serum opsonic capacity appeared to include a noncomplement cofactor for optimal activity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Altered antibody isotype in cystic fibrosis: impaired natural antibody response to polysaccharide antigens

Patients with cystic fibrosis (CF) have impaired natural (preinfection) IgG2 antibody responses to Pseudomonas aeruginosa lipopolysaccharide. To investigate the basis for this defect, we measured natural IgG and IgG1-4 antibody levels to Haemophilus influenzae type b polyribophosphate (PRP) and tetanus toxoid by enzyme-linked immunosorbent assay in 24 adult CF patients and 20 normal controls. Immunoglobulin heavy- and light-chain allotypes were determined on 146 Caucasian CF patients and 96 controls. The tetanus toxoid-specific IgG response was predominantly IgG1. CF and control subjects had similar IgG and IgG1 antibody levels. The PRP-specific IgG response was predominantly IgG2. In contrast to tetanus toxoid results, CF patients had lower geometric mean level of PRP-specific IgG compared to normal controls (p = 0.0036). ELISA results were confirmed by liquid-phase 3H-PRP-binding assay: CF patients had a geometric mean serum antibody level of 395 versus 922 ng/ml in controls (p = 0.0044). PRP-specific IgG2 levels were also depressed in CF patients (p = 0.03). CF patients had a lower prevalence of the A2m(2) allotype than the local racially matched control sample (p less than 0.025). Other allotype prevalences including G2m(n) and Km(1) were similar. Impaired IgG2 antibody responses to microbial polysaccharide surface antigens in CF patients might predispose them to persistent endobronchial infection and lead to production of nonopsonizing isotype responses. The potential role of A2m(2), coded for in the H chain locus on chromosome 14, is unknown, but could be related to mucosal IgA2 antibody responses.