Serology as a diagnostic tool for predicting initialPseudomonas aeruginosa acquisition in children with cystic fibrosis

Recent advances in the early treatment of cystic fibrosis: Bridging the gap to highly effective modulator therapy

Highly effective modulator therapy (HEMT) for cystic fibrosis (CF) has been touted as one of the greatest advances to date in CF care. As these therapies are now available for many older children and adults with CF, marked improvement of their nutritional status, pulmonary and gastrointestinal symptoms has been observed. However, most infants and younger children are not current candidates for HEMT due to age and/or cystic fibrosis transmembrane conductance regulator (CFTR) mutation. For these young children, it is essential to provide rigorous monitoring and care to avoid potential disease sequelae while awaiting HEMT availability. The following article highlights recent advances in the care of infants and young children with CF with regard to surveillance and treatment of nutritional, pulmonary, and gastrointestinal disorders. Recent clinical trials in this population are also reviewed.

Antibody response against Mycobacterium avium complex in cystic fibrosis patients measured by a novel IgG ELISA test

BACKGROUND

Early signs of Mycobacterium avium complex pulmonary disease can be missed in patients with cystic fibrosis due to subclinical infection or delays in mycobacterial culture. The aim of this study was to determine the diagnostic accuracy of a novel enzyme linked immunosorbent assay for immunoglobulin G against Mycobacterium avium complex, which could help stratify patients according to risk.

METHODS

A retrospective cross sectional analysis of serum samples from the Copenhagen Cystic Fibrosis Center was performed. Corresponding clinical data were reviewed and patients with cystic fibrosis were assigned to one of four groups based on their mycobacterial culture results. In addition, anti-Mycobacterium avium complex immunoglobulin G levels were measured longitudinally before and after first positive culture in the period 1984-2015.

RESULTS

Three-hundred and five patients with cystic fibrosis were included with a median of five nontuberculous mycobacterial cultures. Four individuals had Mycobacterium avium complex pulmonary disease at the time of cross sectional testing and their median antibody level was 22-fold higher than patients with no history of infection (1820 vs. 80 IgG units; p < 0.001). Test sensitivity was 100% (95% CI 40-100) and specificity 77% (95% CI 72-81). Longitudinal kinetics showed rising antibodies prior to first positive culture suggesting diagnostic delay.

CONCLUSIONS

Antibody screening for Mycobacterium avium complex may be used as a supplement to culture. Although confirmation in a larger cohort is needed, our findings suggest that stratifying a cystic fibrosis population into high- and low-risk groups based on antibody levels may help clinicians identify patients in need of more frequent culture.

"Pathogen Eradication" and "Emerging Pathogens": Difficult Definitions in Cystic Fibrosis

Infection is a common complication of cystic fibrosis (CF) airway disease. Current treatment approaches include early intervention with the intent to eradicate pathogens in the hope of delaying the development of chronic infection and the chronic use of aerosolized antibiotics to suppress infection. The use of molecules that help restore CFTR (cystic fibrosis transmembrane conductance regulator) function, modulate pulmonary inflammation, or improve pulmonary clearance may also influence the microbial communities in the airways. As the pipeline of these new entities continues to expand, it is important to define when key pathogens are eradicated from the lungs of CF patients and, equally important, when new pathogens might emerge as a result of these novel therapies.

Increased cytokines in cystic fibrosis patients' upper airways during a new P. aeruginosa colonization

OBJECTIVES

Previously, we found linkages of inflammatory mediator levels in CF upper airways (UAW) sampled by nasal lavage (NL) to disease severity and to chronic pathogen colonization such as Pseudomonas aeruginosa (PsA). Here, we assess UAW cytokine dynamics in CF patients with a new PsA colonization.

METHODS

We measured cytokines in 149 longitudinally obtained NL samples from 34 CF patients. Cytokine concentrations determined prior to, at the time of de novo PsA detection in either UAW or lower airways (LAW), and in a subsequent PsA free period in newly colonized patients (PsA-new/n = 7) were compared to levels of not- (PsA-free/n = 13) and chronically colonized patients (PsA-chron/n = 14). Moreover, serological and clinical data were compiled.

RESULTS

Concentrations of IL-1ß, IL-6, and IL-8 in samples taken prior to new PsA detection were comparable with PsA-free patients. At the time of PsA detection and, most interestingly, irrespective of whether PsA occurred in the UAW or LAW, IL-8 increased (P = 0.009) and IL-6 tended to increase (P = 0.081). In these patients, detection of PsA was not related to elevated PsA antibody-titers. In comparison, NL of PsA-chron patients revealed generally lower IL-8 and IL-1β concentrations as in PsA-free patients, most likely due to a consequent antibiotic and anti-inflammatory therapy (eg, with azithromycin).

CONCLUSIONS

Monitoring cytokine dynamics in the UAW by serial NL sampling may be valuable in the early phase of PsA acquisition and, thus, increase the chance to adjust treatment options early and more specifically.

Early Lung Disease in Infants and Preschool Children with Cystic Fibrosis. What Have We Learned and What Should We Do about It?

The past decade has seen significant advances in understanding of the pathogenesis and progression of lung disease in cystic fibrosis (CF). Pulmonary inflammation, infection, and structural lung damage manifest very early in life and are prevalent among preschool children and infants, often in the absence of symptoms or signs. Early childhood represents a pivotal period amenable to intervention strategies that could delay or prevent the onset of lung damage and alter the longer-term clinical trajectory for individuals with CF. This review summarizes what we have learned about early lung disease in children with CF and discusses the implications for future clinical practice and research.

Evaluation of a bovine antibody test for diagnosing Mycobacterium avium complex in patients with cystic fibrosis

INTRODUCTION

The aim of this study was to test a commercial bovine enzyme-linked immunosorbent assay for investigating antibody activity against Mycobacterium avium complex.

METHODS

All patients at the Copenhagen Cystic Fibrosis (CF) Center who had culture for nontuberculous mycobacteria performed were included. A commercially available antibody test used in veterinary medicine, was adjusted for human use, and applied to patient sera in a cross sectional test. The test positivity threshold was determined using a receiver operating curve (ROC). A longitudinal analysis of antibody kinetics before and after culture conversion was performed in case patients.

RESULTS

Out of 286 included subjects, six had clinical M. avium complex pulmonary disease at the time of sera sampling. These patients presented with higher antibody test values (P-value <0.01). A test cut point of 0.78 was chosen, corresponding to a sensitivity of 100% (54-100), specificity of 66% (60-72), a positive predictive value of 6% (2-13), and negative predictive value of 100% (98-100).

CONCLUSION

While not suited for direct diagnosis of M. avium complex due to a high number of false positive subjects, the assay proved useful at ruling out pulmonary disease. Screening sera from patients with CF could guide clinicians to focus attention on patients at higher risk of M. avium complex pulmonary disease. Pediatr Pulmonol. 2017;52:34-40. © 2016 Wiley Periodicals, Inc.

Assessment of serology and spirometry and the combination of both to complement microbiological isolation for earlier detection of Pseudomonas aeruginosa infection in children with cystic fibrosis

Background

The aim of this study was to assess whether serology and spirometry and the combination of both can complement culture-based detection for earlier recognition of Pseudomonas aeruginosa infection in children with cystic fibrosis.

Methods

A 4 year longitudinal prospective study that included 67 Slovenian children with cystic fibrosis with a mean age of 10.5 years was conducted. Serology, spirometry and a scoring system combining serology and spirometry were assessed and compared. Infection was confirmed with isolation of Pseudomonas aeruginosa from respiratory samples.

Results

There was a significantly positive correlation between serology and the combination of serology and spirometry and Pseudomonas aeruginosa isolation (P < 0.01 for both) and a significantly negative correlation between spirometry and Pseudomonas aeruginosa isolation (P < 0.05). An increase in serology for 1 ELISA unit increased the possibility of Pseudomonas aeruginosa isolation 1.6 times. A fall in FEV1% predicted for 10% increased the possibility of Pseudomonas aeruginosa isolation 9.8 times. Binary logistic regression analysis was used to determine the odds ratios and 95% confidence intervals for all three approaches. Serology had the highest specificity (0.80) and the combination of serology and spirometry the highest sensitivity (0.90). Both had a high negative predictive value (0.93 and 0.79 respectively).

Conclusion

Using serology and the combination of serology and lung function measurement can be beneficial for earlier detection of infection with Pseudomonas aeruginosa in children with cystic fibrosis when done simultaneously with standard culture-based detection from respiratory samples.

BPI-ANCA Provides Additional Clinical Information to Anti-Pseudomonas Serology: Results from a Cohort of 117 Swedish Cystic Fibrosis Patients

Patients with cystic fibrosis (CF) colonized with Pseudomonas aeruginosa (P. aeruginosa) have worse prognosis compared with patients who are not. BPI-ANCA is an anti-neutrophil cytoplasmic antibody against BPI (bactericidal/permeability increasing protein) correlating with P. aeruginosa colonization and adverse long time prognosis. Whether it provides additional information as compared to standard anti-P. aeruginosa serology tests is not known. 117 nontransplanted CF patients at the CF centre in Lund, Sweden, were followed prospectively for ten years. Bacterial colonisation was classified according to the Leeds criteria. IgA BPI-ANCA was compared with assays for antibodies against alkaline protease (AP), Elastase (ELA), and Exotoxin A (ExoA). Lung function and patient outcome, alive, lung transplanted, or dead, were registered. BPI-ANCA showed the highest correlation with lung function impairment with an r-value of 0.44. Forty-eight of the 117 patients were chronically colonized with P. aeruginosa. Twenty of these patients experienced an adverse outcome. Receiver operator curve (ROC) analysis revealed that this could be predicted by BPI-ANCA (AUC = 0.77), (p = 0.002) to a better degree compared with serology tests. BPI-ANCA correlates better with lung function impairment and long time prognosis than anti-P. aeruginosa serology and has similar ability to identify patients with chronic P. aeruginosa.

Impact of Sustained Eradication of New Pseudomonas aeruginosa Infection on Long-term Outcomes in Cystic Fibrosis

BACKGROUND

Pseudomonas aeruginosa (Pa) is the most important pathogen infecting the airways in individuals with cystic fibrosis. A key question is whether children with newly acquired Pa infection who are able to achieve sustained eradication after early antipseudomonal therapy demonstrate improved long-term health outcomes compared with those who are unable to achieve a sustained microbiologic response.

METHODS

This cohort study utilized observational follow-up data on children participating in the Early Pseudomonas Infection Control trial who received standardized therapy for newly acquired Pa. Sustained eradicators were defined as those who maintained Pa-negative cultures for 12 months after initial antipseudomonal therapy. Associations between eradication status and outcomes were assessed.

RESULTS

Of the 249 trial participants included in the study, 172 (69%) achieved sustained eradication of Pa during the trial (sustained eradicators). Over the median 5-year follow-up, sustained eradicators had a 74% reduced risk of developing chronic Pa (hazard ratio [HR], 0.26; 95% confidence interval [CI], .17-.40) and a 57% reduced risk of mucoidy (HR, 0.43; 95% CI, .25-.73) compared with nonsustained eradicators. Sustained eradicators had significantly less anti-Pa antibiotic usage during follow-up compared with nonsustained eradicators. There was no association between eradication status and clinical outcomes including rate of exacerbation and lung function decline.

CONCLUSIONS

This is the first study to quantify the long-term durability of microbiological response associated with early antipseudomonal therapy, demonstrating the critical importance of optimizing antipseudomonal therapies during early Pa infection. The clinical impact of failure to achieve sustained Pa eradication remains unclear, however, and may be confounded by anti-Pa antibiotic usage.

CLINICAL TRIALS REGISTRATION

NCT00097773.

Serodiagnosis of Mycobacterium abscessus complex infection in cystic fibrosis

Early signs of pulmonary disease with Mycobacterium abscessus complex (MABSC) can be missed in patients with cystic fibrosis (CF). A serological method could help stratify patients according to risk. The objective of this study was to test the diagnostic accuracy of a novel method for investigating IgG activity against MABSC.A prospective study of all patients attending the Copenhagen CF Centre was conducted by culturing for MABSC during a 22-month period and then screening patients with an anti-MABSC IgG ELISA. Culture-positive patients had stored serum examined for antibody kinetics before and after culture conversion.307 patients had 3480 respiratory samples cultured and were then tested with the anti-MABSC IgG ELISA. Patients with MABSC pulmonary disease had median anti-MABSC IgG levels six-fold higher than patients with no history of infection (434 versus 64 ELISA units; p<0.001). The test sensitivity was 95% (95% CI 74-99%) and the specificity was 73% (95% CI 67-78%). A diagnostic algorithm was constructed to stratify patients according to risk.The test accurately identified patients with pulmonary disease caused by MABSC and was suited to be used as a complement to mycobacterial culture.

Pseudomonas aeruginosa genotypes acquired by children with cystic fibrosis by age 5-years

BACKGROUND

We describe Pseudomonas aeruginosa acquisitions in children with cystic fibrosis (CF) aged ≤5-years, eradication treatment efficacy, and genotypic relationships between upper and lower airway isolates and strains from non-CF sources.

METHODS

Of 168 CF children aged ≤5-years in a bronchoalveolar lavage (BAL)-directed therapy trial, 155 had detailed microbiological results. Overall, 201/271 (74%) P. aeruginosa isolates from BAL and oropharyngeal cultures were available for genotyping, including those collected before and after eradication therapy.

RESULTS

Eighty-two (53%) subjects acquired P. aeruginosa, of which most were unique strains. Initial eradication success rate was 90%, but 36 (44%) reacquired P. aeruginosa, with genotypic substitutions more common in BAL (12/14) than oropharyngeal (3/11) cultures. Moreover, oropharyngeal cultures did not predict BAL genotypes reliably.

CONCLUSIONS

CF children acquire environmental P. aeruginosa strains frequently. However, discordance between BAL and oropharyngeal strains raises questions over upper airway reservoirs and how to best determine eradication in non-expectorating children.

Acute pulmonary exacerbation and lung function decline in patients with cystic fibrosis: high-mobility group box 1 (HMGB1) between inflammation and infection

Airway inflammation plays a central role in cystic fibrosis (CF) lung disease, and biomarkers of inflammation, such as high-mobility group box 1 (HMGB1) could be used to monitor disease activity. The main aim of this study was to confirm the role of HMGB1 in CF patients, correlating its serum and sputum levels with pulmonary function and inflammation. Serum and sputum HMGB1 were evaluated in a cohort of 31 CF patients and 30 non-smoking healthy subjects (HS group). Acute pulmonary exacerbation events and lung function decline have been also evaluated during a 3-year follow-up period. Serum HMGB1 levels were significantly higher than those measured in HS, such as sputum HMGB1. Kaplan-Meier survival curves revealed that patients with high HMGB1 values experienced a significantly faster evolution to decline of lung function. A multiple Cox regression analysis assessed that an increase of serum HMGB1 was associated with 5% increased risk of pulmonary disease progression, whereas elevated sputum HMGB1 was related to a 10% increased risk of lung function decline. In CF patients, HMGB1 closely reflects the entity of pulmonary impairment and represents a strong and independent risk marker for progression of lung function decline.