Nasopharyngeal wash versus swab specimens for culture of nontypeable Haemophilus influenzae and other respiratory bacterial pathogens.

TO THE EDITOR—We read with interest the recent article by Winokur et al, in which they developed a safe experimental human model of nontypeable Haemophilus influenzae (NTHi) nasopharyngeal colonization [1]. In their study, both nasopharyngeal wash specimens and nasopharyngeal swab specimens were collected to culture NTHi. Colonization was detected in nasopharyngeal wash samples from 9 subjects (60%) and in nasopharyngeal swab samples from 6 subjects (40%). Our group has been studying nasopharyngeal colonization of infants and children (age range, 6–30 months) for the past 7 years with the support of the National Institutes of Health’s National Institute on Deafness and Other Communication Disorders. We obtained nasopharyngeal wash, nasopharyngeal swab, and oropharyngeal swab samples during >1500 visits and found that, consistent with results of the study by Winokur et al [1], NTHi, Streptococcus pneumoniae, and Moraxella catarrhalis were more frequently isolated from cultures of nasopharyngeal wash specimens (59%) than from cultures of nasopharyngeal swab samples (48%) [2–4]. Moreover, we found no cases in which culture of nasopharyngeal swab specimens yielded the 3 target bacteria when results of nasopharyngeal wash culture were negative. A previous study by Greenberg et al [5] showed that S. pneumoniae is carried mainly in the nasopharyngeal region, whereas NTHi is carried equally in the nasopharyngeal and oropharyngeal