TABLE 1.

Percentage of B. pertussis detected by PCR determined directly from inoculated swabs and controls

Dilution (n)	% B. pertussis detected with swab type:
	None (control)	Dacron	Rayon	Calcium-alginate	DNA/RNA Protect system
10−3 (10)	100	100	100	50	100
10−4 (10)	100	70	80	20a	90
10−5 (10)	80	10	10	10	50b
10−6 (10)	0	0	0	0	0

^aCalcium-alginate versus all other swabs at the 10⁻⁴ dilution (P < 0.02).

^bDNA/RNA Protect system versus all other swabs at the 10⁻⁵ dilution (P < 0.02).