The clinical significance of oropharyngeal cultures in young children with cystic fibrosis

In children with cystic fibrosis (CF) the associations between oropharyngeal swabs (OPS) for detection of Pseudomonas and lung disease has not been evaluated. OPS and bronchoalveolar lavage (BAL) samples were obtained annually in children with CF from 2005 to 2017. OPS test characteristics were calculated using BAL as gold standard. Results were related to lung inflammation (BAL neutrophil elastase, interleukin-8), structural lung disease (chest CT PRAGMA-CF scores), respiratory exacerbations, and future detection of Pseudomonas on BAL. From 181 patients, 690 paired OPS-BAL cultures were obtained. Prevalence of Pseudomonas in BAL was 7.4%. OPS sensitivity was 23.0% and specificity 91.4%, reducing the post-test probability for a positive BAL following a negative OPS to 6.3%. Pseudomonas on OPS was not associated with lung inflammation or respiratory exacerbations but was weakly associated with current PRAGMA-CF %disease score (p=0.043). Pseudomonas on BAL was associated with positive neutrophil elastase (OR 4.17 CI95% 2.04–8.53, p<0.001), increased interleukin-8 (p<0.001), increased all baseline PRAGMA-CF scores (p<0.001), progression of PRAGMA-CF scores (p<0.05) and increased risk of respiratory exacerbations (IRR 2.11 CI95% 1.15–3.87, p=0.017). In children with CF OPS only marginally change the probability of detecting lower airway Pseudomonas and are not associated with lung disease indices nor exacerbations risk.

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