Table 4.

Biofilm formation does not predict T3SS activity among swim-positive/twitch-positive isolates

	Quartile 1	Quartile 2	Quartile 3	Quartile 4
Biofilm score (n)*	<0.75 (40)	0.75–1.04 (40)	1.05–1.59 (40)	≥1.6 (39)
PopD secretion, median†	32	14.5	40	20
T3SS-positive (n=94)‡	26/40 (65 %)	20/40 (50 %)	26/40 (65 %)	23/39 (59 %)

*Biofilm formation is normalized to PAO1. The number of isolates in each quartile is indicated.

†Median is expressed as a percentage of the PA103 control.

‡Positive defined as ≥15 % of PA103 control; percentage of T3SS-positive strains across quartiles not significantly different (P=0.3, chi-square).