Bacteriological swabs.

Streptococcus pyogenes survives poorly on plain cotton-wool swabs, whereas serum-dipped swabs permit its survival but also allow overgrouth by other bacteria and are likely to contain virus inhibitors. The use of swabs dipped in a solution of 20% bovine albumin (fraction V) and sterilized by steam is therefore recommended, since these permit bacterial survival without growth and are unlikely to contain virus inhibitors.