Table 1. Proportion of L. monocytogenes isolates obtained from large-scale market basket surveys: Present study compared with previous study^a.

Molecular subgroup	This study, 2010–2013 survey isolate collection			Previous studies, 2000–2001 survey isolate collection			P (Fisher’s test) b
	No. isolates for subgroup	Total No.	Percent	No. isolates for subgroup	Total No.	Percent
Lineage I	49	102	48.0%	187	502	37.3%	< 0.05
Lineage II	51		50.0%	313		62.4%
Lineage III	2		2.0%	2		0.4%
inlA without PMSC	91	102	89.2%	275	502	54.8%	< 0.001
inlA with PMSC	11		10.8%	227		45.2%

^a For the present study, isolates were obtained from the 2010–2013 Lm MBS [13] and the molecular subgroup was determined based on WGS data. Isolates obtained from a previous 2000–2001 survey study [12] were further analyzed and molecular subgroups were determined for lineages as reported by Gray et al. [16] and for inlA premature stop codon mutations as reported by Van Stelten et al. [20] with update by Chen et al. [83].

^b The p value shown is for the comparison between isolates from the 2010–2013 and the 2000–2001 surveys.