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Pulmonary infection in mild variant cystic fibrosis: implications for care
1Academic Unit of Child Health, Stephenson Unit, Sheffield Children's Hospital, Western Bank, Sheffield S10 2 TH, United Kingdom.
Insights
Children with mild cystic fibrosis (CF) mutations experience frequent airway infections, often with Staphylococcus aureus and Pseudomonas aeruginosa. Anti-staphylococcal prophylaxis may be beneficial for these young patients.
Area of Science:
- Pediatric Pulmonology
- Genetics
- Infectious Disease
Background:
- Cystic Fibrosis (CF) presents with varied disease severity, particularly in children with mild CFTR gene mutations.
- The airway condition and prognosis for infants and young children with mild CF remain poorly understood, leading to inconsistent management strategies.
- This study investigates pulmonary infections in children with mild variant CF to better understand clinical outcomes.
Purpose of the Study:
- To compare bacterial isolates and clinical outcomes in children with mild CFTR gene mutations versus those with DeltaF508 homozygosity.
- To evaluate the frequency and types of bacterial infections in young CF patients with different mutation profiles.
- To assess differences in pulmonary health indicators, including Shwachman scores, chest radiograph findings, and lung function.
Main Methods:
- A retrospective cohort study design was employed.
- Eleven compound heterozygotes for DeltaF508 and a mild mutation (primarily R117H) were compared to a matched group of DeltaF508 homozygotes.
- Data on bacterial isolates, Shwachman scores, chest radiograph scores, and FEV1 were analyzed.
Main Results:
- Staphylococcus aureus and Pseudomonas aeruginosa were common in mild variant CF patients, with positive cultures occurring less frequently per year (2.8) compared to DeltaF508 homozygotes (6.1).
- Patients with mild mutations had significantly higher Shwachman scores (94 vs. 88) and better chest radiograph scores (5.1 vs. 5.8).
- No significant difference in lung function (FEV1) was observed between the two groups.
Conclusions:
- Children with mild variant CF typically require antibiotic therapy 3-4 times annually due to bacterial airway isolates.
- Co-infection with both S. aureus and P. aeruginosa is frequently observed in this population.
- Consideration of anti-staphylococcal prophylaxis during the initial two years of life is recommended for mild variant CF patients.
Background:
Disease phenotype in cystic fibrosis (CF) shows considerable heterogeneity. Atypical or mild mutations in the CFTR gene have been linked to late-onset pulmonary disease; however, few reports document the condition of the airway in infants and young children with apparent "mild" disease. Prognosis is uncertain in this group of patients and this, in turn, has led to inconsistency in management. Our initial experience of pulmonary infection in children with mild variant CF prompted a more detailed review of clinical outcome.
Methods:
A retrospective cohort study was carried out comparing frequency of bacterial isolates and clinical outcomes in eleven compound heterozygotes for DeltaF508 and a second mild mutation, mainly R117H, with a matched group of DeltaF508 homozygotes.
Results:
Staphylococcus aureus was isolated in 8 of the 11 patients with mild variant disease and Pseudomonas aeruginosa found in 7 (64%), although the frequency of positive cultures was significantly less (2.8/year) than the DeltaF508 homozygotes (6.1/year, p<0.05). Shwachman scores (median+range) were significantly higher in patients with mild mutations - 94, 74-92 vs. 88, 77-91; p<0.005); there was also a small but significant difference in chest radiograph (Chrispin-Norman) scores (median+range) (mild 5.1, 4-9, vs. severe 5.8, 3-10; p 0.04). There was little difference in lung function in terms of FEV1 (median+range) between the two groups (% predicted, mild 86.5, 68-87 vs. severe 76.0, 65-88; p 0.5).
Conclusions:
Most patients with mild variant CF will have bacterial isolates from airway cultures requiring antibiotic therapy three to four times a year. Infection with both S. aureus and P. aeruginosa is common. Anti-staphylococcal prophylaxis for the first two years should be considered.
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