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

Abstract

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.

Diagnostic accuracy and distress associated with oropharyngeal suction in cystic fibrosis

“…This allows for direct comparison of results with previous studies [6,8]. In addition, as the definition of what density of growth constitutes an infection is controversial [5,23], this study provides information for diagnostic accuracy of OPS at different organism densities.…”

“…Rosenfeld et al [6] combined data from three study cohorts, enabling comparison of 171 paired oropharyngeal swab and BAL samples. Kidd et al [8] analysed 257 paired upper airway and BAL samples, of which 249 of the upper airway samples were oropharyngeal swabs (personal communication, T Kidd). Children in these studies had oropharyngeal cultures obtained either following general anaesthetic and prior to BAL or following BAL.…”

“…A sample size was determined by predicting a specificity of 90% for Pseudomonas aeruginosa detection, based on previous studies [6,8], setting an acceptable 95% confidence interval width of 10% for specificity, and using the current prevalence of P.aeruginosa in children under 5 years of age in our clinic population of 10%. It was determined that 39 paired samples would be required to exhibit this level of diagnostic accuracy [20].…”

“…However, these methods have been shown to have variable diagnostic accuracy when compared to BAL [6][7][8] or expectorated sputum [9][10][11]. Furthermore, common CF pathogens are present in the upper airways of healthy children [12,13], further complicating meaningful interpretations of positive upper airway bacterial cultures.…”

The microbiology of the cystic fibrosis upper and lower airway

“…Of the paired samples though, 72% were reported to have an indistinguishable ERIC-PCR genotype between the upper and lower airways [1].…”