Comparison of Rayon and Dacron Swabs in Amies Medium for Bordetella Pertussis Transport

Synthetic swabs (rayon and Dacron) are used to collect specimens for bacterial culture in preference to cotton swabs which may contain inhibitory or toxic substances. Regan-Lowe medium has been traditionally recommended for Bordetella transport. Little work has been done to determine the performance and suitability of synthetic fiber swabs used in conjunction with Amies charcoal transport medium (TM) for the maintenance of Bordetella pertussis. Suspensions from 20 fresh isolates of  Bordetella pertussis were adsorbed onto rayon and Dacron tipped swabs and placed in Amies charcoal TM (Copan Italia, Brescia, Italy) and stored at room temperature. Swabs from Amies TM were plated to Regan-Lowe medium at 0, 24, 48, 72 and 96 hours. Recovery of organisms from each swab type was quantified using a plate count technique. The recovery from triplicate platings of each swab type was equivalent. Average plate counts dropped with each extra day of storage in TM. At 96 hours the counts from the rayon and Dacron swabs were 13.8% and 9.3% respectively of the 0 hours counts. We conclude that either rayon or Dacron is a suitable swab material for pertussis cultures.