Is the use of supermarket trolleys microbiologically safe? Study of microbiological contamination

Figures & data

Figure 1. Flowchart of sampling in the trolleys.

Table 1. Contamination rates of surfaces at different supermarket companies (A, B, C) locations and shopping trolley materials.

Factor	Microorganism	Level	n / total (%)*	P-value	OR (95%CI)
Company	Enterobacteria (1)	A	22/35 (62.9)^a	.003	1
		B	7/30 (23.3)^b		0.180 (0.061–0.534)
		C	6/20 (30.0)^b		0.253 (0.078–0.821)
	Coliforms (1)	A	14/25 (56.0)^a	.013	1
		B	6/30 (20.0)^b		0.196 (0.060–0.648)
		C	2/10 (20.0)^a ^, ^b		0.196 (0.035–1.118)
	Enterobacteria (2)	A	24/35 (68.6)^a	.008	1
		B	9/30 (30.0)^b		0.196 (0.068–0.566)
		C	9/18 (50.0)^a ^, ^b		0.458 (0.143–1.473)
	Coliforms (2)	A	15/25 (60.0)^a	.028	1
		B	10/30 (33.3)^b		0.333 (0.111–1.004)
		C	7/9 (77.8)^a		2.333 (0.400–13.609)

(*) Distinct superscripts (^{a , b , c}) indicate significant differences for p < .05.

Surface sampled: 1, handles; 2, food baskets-child seats.

Table 2. Contamination rates of surfaces at different locations and shopping trolley materials.

Factor	Microorganism	Level	n / total (%)*	P-value	OR (95%CI)
Location	Enterobacteria (1)	Inside	13/40 (32.5)	.125	1
		Outside	22/45 (48.9)		1.987 (0.822–4.803)
	Coliforms (1)	Inside	8/40 (20.0)	.003	1
		Outside	14/25 (56.0)		5.091 (1.684–15.390)
	Enterobacteria (2)	Inside	16/39 (41.0)	.100	1
		Outside	26/44 (59.1)		2.076 (0.864–4.989)
	Coliforms (2)	Inside	17/39 (43.6)	.200	1
		Outside	15/25 (60.0)		1.941 (0.700–5.384)
Material	Enterobacteria (1)	Metal	7/24 (29.2)	.158	1
		Plastic	28/61 (45.9)		2.061 (0.747–5.681)
	Coliforms (1)	Metal	6/14 (42.9)	.527	1
		Plastic	16/51 (31.4)		0.610 (0.181–2.049)
	Enterobacteria (2)	Metal	9/22 (40.9)	.289	1
		Plastic	33/61 (54.1)		1.702 (0.634–4.572)
	Coliforms (2)	Metal	6/13 (46.2)	.756	1
		Plastic	26/51 (51.0)		1.213 (0.358–4.113)

(*) Distinct superscripts (^{a, b, c}) indicate significant differences for p < .05.

Surface sampled: 1, handles; 2, food baskets-child seats.

Table 3. Relation of the bacteria of special interest isolated from trolleys identified with MALDITOF.

Isolated Bacteria	n / total (%)
E. coli	4 (2.4)
Klebsiela pneumoniae	11 (9.3)
Citrobacter freundi	9 (5.3)
Pseudomonas rhodesiae	4 (2.3)
Pseudomonas fluorescens	3 (1.7)
Enterococcus faecalis	3 (1.7)
Staphylococcus haemolyticus	3 (1,7)
Streptococcus gallolyticus	3 (1.7)
Morganella morganii	2 (1.2)
Proteus mirabilis	2 (1.2)
Enterobacter asburiae	2 (1.2)