title: Comparison of nasal swab culture, quantitative culture of nasal mucosal tissue and PCR in detecting Streptococcus pneumoniae carriage in rats.
abstract: It is not known how well nasopharyngeal swab culture represents pneumococcal carriage status. We tested this by comparing swab culture to quantitative culture and quantitative PCR of mucosal tissue in a rat model of pneumococcal carriage. Quantitative culture and quantitative PCR identified significantly more carriers compared to swab culture (differences 15% and 33%, 95% CI 1-28% and 16-47%, p=0.04 and 0.001, respectively). The sensitivity and specificity of swab culture was 75/92% and 63/100% compared to quantitative tissue culture and quantitative PCR, respectively. The quantitative estimates of culture and PCR were very similar (Pearson correlation coefficient 0.79, p<0.001). In conclusion, even a well-controlled swab sampling markedly underestimates pneumococcal carriage rate, and simultaneous use of quantitative culture and PCR increases the number of positive samples by about one third.
authors.affiliation: The Department of Pediatrics, University of Oulu, Finland. tero.kontiokari@oulu.fi
authors.forename: T
authors.initials: T
authors.lastname: Kontiokari
authors.forename: M
authors.initials: M
authors.lastname: Renko
authors.forename: T
authors.initials: T
authors.lastname: Kaijalainen
authors.forename: L
authors.initials: L
authors.lastname: Kuisma
authors.forename: M
authors.initials: M
authors.lastname: Leinonen
mesh_terms: D000818:Animals; D002353:Carrier State / Q000175:diagnosis*; D009297:Nasal Mucosa / Q000382:microbiology*; D009305:Nasopharynx / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000175:diagnosis*; D016133:Polymerase Chain Reaction; D051381:Rats; D017207:Rats, Sprague-Dawley; D012680:Sensitivity and Specificity; D013048:Specimen Handling; D013296:Streptococcus pneumoniae / Q000302:isolation & purification*