Swabbing for respiratory viral infections in older patients: a comparison of rayon and nylon flocked swabs.
Author(s): Hernes SS, Quarsten H, Hagen E, Lyngroth AL, Pripp AH, Bjorvatn B, Bakke PS
Publication: Eur J Clin Microbiol Infect Dis, 2011, Vol. 30, Page 159-65
PubMed ID: 20853014 PubMed Review Paper? No
Purpose of Paper
This paper compared the diagnosis of respiratory viruses by real-time RT-PCR in oropharyngeal and nasopharyngeal specimens collected with rayon or nylon flocked swabs.
Conclusion of Paper
At least one swab was positive for viral RNA in 11% of participants. Average cycle threshold (CT) values were lower in nasopharyngeal than oropharyngeal swabs specimens resulting in a 19-fold higher calculated viral load in nasopharyngeal specimens, regardless of swab type. Specimens collected using nylon flocked swabs had lower average CT values (higher calculated viral loads) compared to those collected using rayon swabs, regardless of specimen sampling location.
Studies
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Study Purpose
This study compared the diagnosis of respiratory viruses by real-time RT-PCR in oropharyngeal and nasopharyngeal specimens collected with rayon or nylon flocked swabs. Specimens were collected from 223 patients (134 males, 89 females, mean age 74.9 years) presenting with at least one respiratory infection symptom (nasal congestion or runny nose, throat pain, fever, malaise, muscle pain). Specimens were collected with a rayon or nylon flocked swab (order of swab type used was randomly selected) from the right oropharynx, left oropharynx, left nasopharynx, and then right nasopharynx. Swabs were stored at room temperature ≤48 h until RNA extraction using a MagNA Pure LC system. cDNA synthesis was performed with the qScript cDNA Synthesis Kit. Mycoplasma pneumoniae, Chlamydophila pneumoniae, Bordetella pertussis, influenza A and B; parainfluenza types 1, 2, 3, and 4; adenovirus; human metapneumovirus (hMPV); and respiratory syncytial virus (RSV) were detected using a multiplex real-time RT-PCR assay. A CT value of 38 was designated as the cut-off value for positive results.
Summary of Findings:
At least one swab was positive for viral RNA in 11% (19/223) of participants. Average CT values were lower in nasopharyngeal than oropharyngeal swabs specimens (4.25 cycles, P<0.001) resulting in a 19-fold higher calculated viral load in nasopharyngeal specimens, regardless of swab type. Specimens collected using nylon flocked swabs had lower average CT values (higher calculated viral loads) compared to those collected using rayon swabs (2.25 cycles, P=0.017), regardless of specimen sampling location.
Biospecimens
Preservative Types
- None (Fresh)
Diagnoses:
- Pneumonia/Respiratory Infection
Platform:
Analyte Technology Platform RNA Real-time qRT-PCR Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Acquisition Biospecimen location Nasopharynx
Oropharynx
Real-time qRT-PCR Specific Targeted nucleic acid Mycoplasma pneumoniae
Chlamydophila pneumoniae
Bordetella pertussis
Influenza Type A
Influenza Type B
Parainfluenza type 1
Parainfluenza type 2
Parainfluenza type 3
Parainfluenza type 4
Adenovirus
Human metapneumovirus
Respiratory syncytial virus
Biospecimen Acquisition Method of cell acquisition Nylon flocked swab
Rayon swab