The effectiveness of four different sampling techniques in detecting carriage of potential upper airway pathogens in children: a pilot study

Background: An upper respiratory tract infection (URTI) is the most common illness affecting young children. To identify the pathogens involved in upper respiratory tract infections, the gold standard is to perform a nasopharyngeal swab (NPS), which can be experienced as unpleasant. Objective: To investigate whether non-invasive sampling methods, i.e. nasal swab (NS), swab from the tissue (NBS) and blowing/wiping the nose in a tissue, are as effective as the NPS. We also studied which method appeared to be most convenient. Methods: After randomising the sampling method order, our different samples were obtained in 16 children aged 0 to 4 years with a runny nose. Concordance and discordance rates for NPS and NS, NBS and NB cultures were calculated for M. catarrhalis, S. pneumoniae, H. influenzae and S. aureus. Differences in VAS scores between the different sampling methods were studied. Results: The concordance rates of the NPS and NS cultures varied from 75% to 100%. The rates for a positive NPS but negative NS had a maximum of 18.75%. The rates for a negative NPS but a positive NS culture were on the other hand lower; 6.25. The concordance rates of the NPS and NBS cultures varied from 81% to 94%. The rates for a positive NPS but negative NBS had a maximum of 13%. The rates for a negative NPS but a positive NBS culture were on the other hand lower; 6.25. The concordance rates of the NPS and NB varied from 69% to 94%.The rates for a positive NPS but negative NB had a maximum of 25%. The rates for a negative NPS but a positive NS culture were 19%. Furthermore, VAS scores for NB and NPS differed significantly, whereas the other differences did not differ significantly. Conclusions: Due to the small sample size this study should be seen as pilot from which no firm conclusions can be drawn. The interim results of 16 children suggest that concordance rates between NPS and NS, and between NBS and NB exceed the discordance rates. Nevertheless, the NPS remains the most valid method.