In Mexico City, fresh-squeezed street-vended orange juice is contaminated with fecal coliforms, <i>Escherichia coli</i>, and Shiga toxin-producing <i>E. coli</i>: A potential risk for acquiring foodborne diseases

FIGUEROA-DUCOING, Belem Karina; CARRILLO-SANCHEZ, Alma Karina; RIVERA-GUTIERREZ, Sandra; RIOS-MUÑIZ, Diana; ESTRADA-GARCIA, Teresa; CERNA-CORTES, Jorge Francisco

doi:10.1590/fst.52022

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Original Article • Food Sci. Technol 42 • 2022 • https://doi.org/10.1590/fst.52022 copy

In Mexico City, fresh-squeezed street-vended orange juice is contaminated with fecal coliforms, Escherichia coli, and Shiga toxin-producing E. coli: A potential risk for acquiring foodborne diseases

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Abstract

This study evaluated the microbiological quality and prevalence of Escherichia coli and diarrheagenic E. coli pathotypes (DEP) among fresh-squeezed orange juice from street vendors and their hygienic practices. Sixty orange juice stalls in Mexico City were visited, and 60 samples were purchased. Most (65%) of the street vendors had poor hygienic practices. Twelve (20%) prepared orange juice at the time of purchase, while the other stalls sold already-squeezed orange juice. All samples analyzed were positive for aerobic mesophilic bacteria, with limits ranging from 1 to 6.8 log CFU/mL. A total of 35 (58.3%), 27 (45%), and 5 (8.3%) samples were positive for total coliforms, fecal coliforms, and E. coli, respectively, present at concentrations ranging from < 3 to > 1100, < 3 to > 1100, and < 3 to 53 MPN/mL, respectively. Two samples harbored DEP at concentrations of 3.6 and 9.2 MPN/mL. Both samples harbored Shiga toxin-producing E. coli strains, positive for the Shiga toxin 2 (stx2) locus. Our results suggest that consumption of fresh-squeezed street-vended orange juice may pose a health risk for consumers, revealing the necessity to implement adequate hygiene and safety practices to protect the health of consumers.

Keywords:
street-vended orange juice; hygienic practices; microbiological quality; Escherichia coli; Shiga toxin-producing E. coli

Microorganisms	Presumptive test or primary enrichment	Confirmatory test or secondary enrichment	Selective medium for isolation	Identification test	Results reported as
Aerobic mesophilic bacteria	NR^a	Plate count agar (Bioxon^TM, BD, State of Mexico, Mexico) for 48 h at 35 °C	NR	NR	CFU/mL^b
Total coliforms	Lactose broth (Difco^TM, BD, Sparks, MD, USA) for 48 h at 35 °C	Brilliant green lactose bile broth (Difco^TM, BD, Sparks, MD, USA) for 48 h at 35 °C	NR	Gas production	MPN/mL^c
Fecal coliforms	Lactose broth (Difco^TM, BD, Sparks, MD, USA) for 48 h at 35 °C	Escherichia coli broth (Difco^TM, BD, Sparks, MD, USA) for 48 h at 44.5 °C	NR	Gas production	MPN/mL
Escherichia coli	Lactose broth (Difco^TM, BD, Sparks, MD, USA) for 48 h at 35 °C	Escherichia coli broth with MUG (4-methylumbelliferyl-β-D-glucuronide) (Difco^TM, BD, Sparks, MD, USA) for 48 h at 44.5 °C	Eosin methylene blue agar (Bioxon^TM, BD, State of Mexico, Mexico) for 24 h at 35 °C	Indole production, methyl red test, Voges-Proskauer test, and citrate utilization (Bioxon^TM, BD, State of Mexico, Mexico) for 24 h at 35 °C	MPN/mL

Microorganisms	Minimum	Median	Maximum	Number of positive samples (%)
AMB	1	3.2	6.8	60 (100)
TC	< 3	3.6	> 1100	35 (58.3)
FC	< 3	< 3	> 1100	27 (45)
E. coli	< 3	< 3	53	5 (8.3)
DEP	< 3	< 3	9.2	2 (3.3)

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[1] *Corresponding author: jcernac@ipn.mx