TABLE 4.

Correlational analysis of biofilm phage response and strength of biofilm formation^a

Phage	Levels of biofilm formation	No. of isolates	Levels compared	P value
ATCC 11988-B1	0	2	1−0	0.3502
	1	4	2−1	0.1507
	2	16	2−0	0.0045
ATCC 19685-B1	0	0	2−1	0.1602
	1	2
	2	78
ATCC 23360-B1	0	0	2−1	0.0462
	1	1
	2	61

^aThe Wilcoxon signed rank test was used to relate strength of biofilm formation and biofilm phage response as measured by percent reduction in treated versus control conditions, α = 0.05. Replicates were assigned categories of strength of biofilm formation established by Stepanovic et al. (68), as 0 = nonadherent or weak biofilm formers; 1 = weak/moderate or moderate biofilm formers; or 2 = moderate/strong or strong biofilm formers. Isolates were analyzed if biological replicates yielded the same or adjacent categorical assignments. Statistics were calculated for differences in percent biomass reduction between biofilm formation levels per phage.