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Open Access Research article

Comparison between nasopharyngeal swab and nasal wash, using culture and PCR, in the detection of potential respiratory pathogens

Jenna F Gritzfeld1*, Paul Roberts2, Lorna Roche3, Sherouk El Batrawy2 and Stephen B Gordon1

Author Affiliations

1 Respiratory Infection Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK

2 NIHR Biomedical Research Centre, Directorate of Infection and Immunity, Royal Liverpool and Broadgreen University Hospitals NHS Trust, Liverpool, UK

3 Royal Liverpool Hospital, Cheshire and Merseyside Comprehensive Local Research Network, Liverpool, UK

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BMC Research Notes 2011, 4:122  doi:10.1186/1756-0500-4-122

Published: 13 April 2011

Abstract

Background

Nasopharyngeal carriage of potential pathogens is important as it is both the major source of transmission and the prerequisite of invasive disease. New methods for detecting carriage could improve comfort, accuracy and laboratory utility. The aims of this study were to compare the sensitivities of a nasopharyngeal swab (NPS) and a nasal wash (NW) in detecting potential respiratory pathogens in healthy adults using microbiological culture and PCR.

Results

Healthy volunteers attended for nasal washing and brushing of the posterior nasopharynx. Conventional and real-time PCR were used to detect pneumococcus and meningococcus. Statistical differences between the two nasal sampling methods were determined using a nonparametric Mann-Whitney U test; differences between culture and PCR methods were determined using the McNemar test.

Nasal washing was more comfortable for volunteers than swabbing (n = 24). In detection by culture, the NW was significantly more likely to detect pathogens than the NPS (p < 0.00001). Overall, there was a low carriage rate of pathogens in this sample; no significant difference was seen in the detection of bacteria between culture and PCR methods.

Conclusions

Nasal washing and PCR may provide effective alternatives to nasopharyngeal swabbing and classical microbiology, respectively.