New ASM Algorithm for Flu A Recommends Nasopharyngeal Flocked Swabs

ASM's 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 (ASM resources for Influenza A (H1N1) (Swine Flu)).

The document provides a detailed flowchart that guides microbiologists and physicians through patient assessment, 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, a product manufactured and patented 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's Flocked Swabs, NP aspirates and washes had been the gold standard for specimen collection for respiratory virus diagnostics because traditional swabs had proven to be considerably inferior in terms of the amount of patient sample they were able to collect and the ability to transfer that sample into the test platform. Conversely, the aspirate or wash procedure has the potential to rinse and remove large quantities of patient sample. The widespread endorsement of Flocked Swabs can be attributed to the unique design of the applicator that comprises of tens of thousands of short nylon fiber strands sprayed onto the tip of the applicator in perpendicular fashion, which is the architecture that 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 have good absorption but then 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 a foam swab, and then the Flocked Swab sample stays very close to the surface for complete and spontaneous release into any test system.

Endorsement of Flocked Swabs as the specimen of choice for Influenza testing follows the publication of numerous clinical studies that have demonstrated equivalent or better test results when compared with NP aspirates or washes, which until now have been the benchmark for all respiratory sample collection. These comparative studies can be reviewed by accessing this link http://www.copanusa.com/studies/index.php.

Flocked Swabs are easier to use, cause less patient discomfort and can be collected at remote centers, whereas NP aspirates and washes can only be performed in a hospital setting by trained personnel with material cost that far exceeds that of a Flocked Swab. Flocked Swabs have proven to be the most superior and easy to use swab technology that is able to equate to the high specimen yields that one is accustomed to with aspirates and washes.