Flocked swabs have been hailed by the microbiology and diagnostic communities for their ability to absorb and elute more specimen than traditional fiber or foam swabs. But not all flocked swabs are created equal.
Some flocked swabs, like Copan's eSwab, are coated with biopolymers that are said to “improve the recovery and survival of organisms.”
However, a recent study published in the Indian Journal of Medical Microbiology has concluded that coating flocked swab tips does “not uniformly demonstrate higher recovery compared with their uncoated counterparts.”1
Additionally, there is evidence that protein solubilization from the swab-tip may affect the storage viability of the samples collected.
In a 2012 letter to the editor published in the Journal of Clinical Virology, Christophe Indevuyst of the Laboratory Medicine at University Hospitals Leuven in Belgium hypothesizes that "the pretreatment of [Copan’s eSwab flocked swab] with a vegetal protein…has a toxic effect on cell cultures."2
Here’s more information on the study published in the Indian Journal of Medical Microbiology:
The goal of this study was to address the assertion that coating swab heads with biopolymers such as protein improves the recovery and survival of organisms, and “to assess the effect of swab head material coating, water absorption capacity and capture and release characteristics of four pathogenic bacteria from protein coated and uncoated flocked swabs."
Prototype of protein (bovine serum albumin) coated minitip HydraFlock® flocked swab
Prototype of uncoated HydraFlock® minitip flocked swab
Prototype of protein coated minitip PurFlock® Ultra flocked swab
Prototype of uncoated minitip PurFlock® Ultra flocked swab
Commercially available Copan minitip Nylon Flocked
Commercially available Copan minitip protein coated ESwab™
The researchers obtained test organisms and performed water absorption tests on whole swabs (five of each type), separated swab fibers (five samples for each type) and the culture studies to evaluate the collection and release of bacteria. Twelve swabs of each swab type were used for culture studies and each organism was cultured in triplicate.
The researchers found that protein coating of swab tips did not uniformly demonstrate higher recovery compared with their uncoated counterparts. The researchers also note that the “higher water absorption of swab tip fibres of uncoated HydraFlock® that potentially prevents desiccation of microbes, coupled with overall superior collection and release of test bacteria among test swabs, is likely to be the choice for clinical diagnostics.”
Puritan’s HydraFlock® flocked swab absorption capacity is dictated by the high-quality fibers and proprietary flocking method we employ. We don’t need to coat our swab tips (and potentially compromise sample viability) because our swabs are absorbent enough on their own.
To learn more about what makes Puritan flocked swabs the superior choice for microbiologists and diagnosticians, click below to speak with one of our knowledgable product specialists.
SOURCES:
1.Harry KH, Madhusudhan KT. Effect of protein coating of locked swabs on the collection and release of clinically important bacteria. Indian J Med Microbiology 2014;32:301-3. Retrieved December 8, 2014 from: http://www.puritanmedproducts.com/assets/uploads/general/Effect_of_protein_coating_of_flocked_swabs_on_the_collection_and_release_of_clinically_important_bacteria-1.pdf
2.eSwab flocked swabs unfit for viral culture. Journal of Clinical Virology 55 (2012) 282–283. [Article access purchased from http://www.journalofclinicalvirology.com/article/S1386-6532(12)00259-4/abstract December 11, 2014]