Comparison of physical characteristics and collection and elution performance of clinical swabs

Abstract

Diagnostic sensitivity of a clinical test is a function of the number of organisms collected and eluted from the swab head that is attributed to the type of fibers and their physical characteristics. To relate these properties, water and protein absorption of nylon flocked, rayon flocked, and HydraFlock® and macrofoam swabs manufactured by Puritan Medical Products, and nylon flocked swab made by Copan Diagnostics were determined. The water and protein absorption capacities of whole swabs ranged from 17 to 21.5% and 13.6 to 19.6%, respectively. The HydraFlock® swab exhibited the highest water and protein absorption capacities in the group. Among the swab tip materials tested, macrofoam exhibited the highest water absorption capacity. Zeta potential of flocked swab fibers as a function of pH showed differences in charged groups depending on fiber types. The collection and release of bacteria with swabs using suspensions of clinically important pathogenic bacteria demonstrated the highest (69%) overall recovery by HydraFlock® swab and macrofoam swab ranked second (62%). The recovery of Gram-negative bacteria was significantly higher compared to Gram-positive bacteria across the swab types. The results of the present study indicate potential superiority of HydraFlock® swab over other swabs in a clinical setting and by collecting and releasing significantly larger numbers of bacteria. Key words: Flocked swabs, water absorption, zeta potential, and pathogenic bacteria.