Article Text
Abstract
Background Detection of pneumonia-causing respiratory viruses in the nasopharynx of asymptomatic children has made their actual contribution to pneumonia unclear. We compared nasopharyngeal viral density between children with and without pneumonia to understand if viral density could be used to diagnose pneumonia.
Methods Nasopharyngeal swabs (NPS) were collected from hospitalised pneumonia cases at Princess Margaret Hospital (PMH) and contemporaneous age-matched controls at PMH outpatient clinics and a local immunisation clinic in Perth, Australia. The density (copies/mL) of respiratory syncytial virus (RSV), influenza A virus (InfA), human metapneumovirus (HMPV) and rhinovirus in NPS was determined using quantitative PCR. Linear regression analysis was done to assess the trend between viral density and age in months. The association between viral density and disease status was examined using logistic regression. Area under receiver operating characteristic (AUROC) curves were assessed to determine optimal discriminatory viral density cut-offs.
Results Through May 2015 to October 2017, 230 pneumonia cases and 230 controls were enrolled. Median nasopharyngeal density for any respiratory virus was not substantially higher in cases than controls (p>0.05 for each). A decreasing density trend with increasing age was observed—the trend was statistically significant for RSV (regression coefficient −0.04, p=0.004) but not for other viruses. After adjusting for demographics and other viral densities, for every log10 copies/mL density increase, the odds of being a case increased by six times for RSV, three times for HMPV and two times for InfA. The AUROC curves were <0.70 for each virus, suggesting poor case–control discrimination based on viral density.
Conclusion The nasopharyngeal density of respiratory viruses was not significantly higher in children with pneumonia than those without; however, the odds of being a case increased with increased density for some viruses. The utility of viral density, alone, in defining pneumonia was limited.
- pneumonia
- respiratory infection
- viral infection
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
Statistics from Altmetric.com
Footnotes
Contributors MUB: participant enrolment, data collection, specimen collection, data analysis, first draft manuscript and subsequent versions. TS: conceive the study, supervise data collection, supervise data analysis and critical review of manuscript. CS: laboratory testing and critical review of manuscript. JL: laboratory testing and critical review of manuscript. MB: conceive the study, support data collection and critical review of manuscript. AM: conceive the study, support data collection and critical review of manuscript. PR: conceive the study and critical review of manuscript. AJ: conceive the study and critical review of manuscript. DS: conceive the study, supervise laboratory testing, interpret laboratory finding and critical review of manuscript. CB: conceive the study, supervise data collection, interpret laboratory analysis, supervise data analysis and critical review of manuscript.
Funding This work was supported by the Telethon-Perth Children’s Hospital Research Fund, Perth Children’s Hospital Foundation and Telethon Kids Institute. TS and CB are supported by NHMRC Career Development Fellowships.
Competing interests PR receives grants from GlaxoSmithKline, Novavax, Medimmune and Janssen outside the submitted work;
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Patient consent for publication Not required.
Ethics approval The protocol was approved by Human Research Ethics Committee of the PMH (PMH HREC REF# 2 014 117EP).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplementary information.