267. Nasopharyngeal Colonization of Adults Hospitalized with Acute Respiratory Disease: Feasibility of Molecular Detection and Typing of Streptococcus pneumoniae from Nasopharyngeal Swabs
Session: Poster Abstract Session: Diagnostic Microbiology; Novel Molecular Methods
Thursday, October 3, 2013
Room: The Moscone Center: Poster Hall C
Background: Nasopharyngeal (NP) colonization with S. pneumoniae (Spn) is common in children; conjugate pneumococcal vaccines reduce rates of NP colonization resulting in direct and indirect disease prevention. Colonization rates and serotype distribution have not been well characterized in adults. This information is critical to predict and monitor population benefit of conjugate Spn vaccines in adults. We developed a screening method using real-time PCR for the detection of Spn from NP swabs collected for respiratory testing and evaluated the PCR-based typing method developed by the Centers for Disease Control and Prevention (CDC).

Methods: Active surveillance for influenza, community-acquired pneumonia (CAP) and invasive pneumococcal disease (IPD) amongst hospitalized adults was conducted by the PCIRN Serious Outcomes Surveillance Network in 2011/12. Patients admitted with an acute respiratory illness (ARI) had an NP swab collected for influenza and Spn PCR.  Real-time PCR using the lytA target was performed and the CDC multiplex PCR assay was used to type positives.

Results: 53/551 (9.6%) of adults hospitalized with ARI were colonized with Spn.  Of those colonized, 34/53 (64%) had CAP, 4/53 (7.5%) had IPD, 2/53 (3.8%) had CAP + IPD, and 13/53 (24.5%) had another respiratory illness. Colonized patients were not statistically significantly different than non-colonized patients with respect to age, gender, smoking,  pneumococcal vaccine, or pulmonary comorbidity. Hospital outcomes did not differ between colonized and non-colonized patients. 22/53 (42%) of positives were typeable using multiplex PCR but a definitive type could be determined in only 10/53 (19%). Overall, the most common types isolated were 19A, 19F, 23B, and 7F or 7A.

Conclusion: Colonization with  Spn is common among adults hospitalized with respiratory illness. Molecular detection of  Spn directly from NP swabs collected for respiratory virus testing is a feasible way to monitor colonization rates in adults before and after implementation of conjugate pneumococcal vaccine programs. The CDC multiplex assay is an accurate and reliable method for typing Spn but additional sequencing will be required to discriminate the type of some strains if this technique is to be used to monitor impact of vaccination on strain distribution.

Amanda Lang, PhD1, Jason Leblanc, PhD1, Todd Hatchette, MD1, Lingyun Ye, PhD1, Donna Mackinnon-Cameron, MMath1, May Elsherif, MD1, Shelly Mcneil, MD, FIDSA1 and on behalf of the Public Health Agency of Canada/Canadian Institutes of Health Research Influenza Research Network (PCIRN) Serious Outcomes Surveillance Network Investigators, (1)Canadian Center for Vaccinology, IWK Health Centre and Capital Health, Dalhousie University, Halifax, NS, Canada

Disclosures:

A. Lang, Pfizer Canada: Grant Investigator, Research grant

J. Leblanc, Pfizer Canada: Grant Investigator, Grant recipient

T. Hatchette, Pfizer Canada: Grant Investigator, Research grant

L. Ye, Pfizer Canada: Grant Investigator, Research grant

D. Mackinnon-Cameron, Pfizer Canada: Grant Investigator, Research grant

M. Elsherif, Pfizer Canada: Grant Investigator, Research grant

S. Mcneil, Pfizer Canada: Grant Investigator, Research grant

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