Nasopharyngeal Flocked Swabs are recommended for H1N1 and influenza A testing

Oct 28 2009

Preparing for this flu season, the American Society for Microbiology (ASM) PSAB Committee on Laboratory Practices has recently published a new interim algorithm providing guidance to clinical laboratories responsible for testing patients with respiratory illness for Influenza A, including H1N1.

The document provides a detailed flowchart that guides microbiologists and physicians through patient assessment and differential diagnosis, and provides recommendations for confirmatory testing. The algorithm focuses particular attention on the critical first step, collection of an optimal specimen, because this step determines the sensitivity and accuracy of the diagnosis. The ASM recommends Nasopharyngeal (NP) Flocked Swabs, patented and manufactured by Copan, as the specimen of choice for Influenza testing. In addition to NP Flocked Swabs, NP aspirates, NP washes, or nasal aspirates are also recommended for testing.

Until the introduction of Copan Flocked Swabs, NP aspirates and washes had been the gold standard for specimen collection for respiratory virus diagnostics because traditional fiber swabs are inferior in terms of the amount of patient sample they collect and the ability to transfer that sample into the test platform. Conversely, the aspirate or wash procedure rinses and removes large quantities of patient sample. The widespread endorsement of Flocked Swabs is attributed to the unique design of the applicator which enables improved sample collection and transfer. The success of Flocked Swabs for Influenza testing is due to a combination of a brush-like action that dislodges large numbers of infected cells and capillary hydraulics, which draws liquid sample between the perpendicular fibers. The Flocked Swabs have a unique mechanical and hydrophilic advantage over any other swab technology. Unlike fiber swabs, which absorb well but entrap the sample in a mattress core, and foam swabs, which are hydrophobic and have poor sample uptake, Flocked Swabs collect a large sample volume -- almost four times more than foam swabs -- and then spontaneously release it into any test system.

Endorsement of Copan Nasopharyngeal Flocked Swabs as the specimen of choice for Influenza testing follows the publication of numerous clinical studies that demonstrate equivalent or better test results when compared with NP aspirates or washes. Copan Flocked Swabs are easier to use, cause less patient discomfort and can be used for sample collection at remote centers, whereas NP aspirates and washes must be performed in a hospital setting by trained personnel with material cost that exceeds that of Flocked Swabs. Copan Flocked Swabs are the best swab technology for Influenza testing that equates to the high specimen yields that laboratory professionals are accustomed to with NP aspirates and washes.