Salmonella and Shigella in Freshly Squeezed Orange Juice, Fresh Oranges, and Wiping Cloths Collected from Public Markets and Street Booths in Guadalajara, Mexico: Incidence and Comparison of Analytical Routes

Abstract

A survey of the presence of Salmonella and Shigella in freshly squeezed orange juice and related samples was conducted in Guadalajara, Mexico. One hundred samples of freshly squeezed orange juice were collected from 49 street booths and 51 small food service establishments. In addition, 75 fresh orange samples, each consisting of five orange units, and 75 wiping cloths were collected from the same establishments from which juice had been collected. Salmonella was isolated from 14, 20, and 23% of samples of orange juice, orange surfaces, and wiping cloths collected from street vendors, while Shigella was isolated from 6, 17, and 5% of these samples. In general, the frequency of isolation of these pathogens in samples from juice serving establishments at public markets was significantly lower than that found among street vendors (P < 0.05). Salmonella enterica serotypes Agona, Typhimurium, and Anatum were found in orange juice, fresh oranges, and wiping cloth samples, while serotype Mexico was found on fresh oranges and in wiping cloths and serotypes Muenchen and Panama were found only in wiping cloth samples. Regarding Shigella species, Shigella sonnei was found in all three types of sample tested; Shigella dysenteriae was found in juice and orange samples, Shigella boydii in orange and wiping cloth samples, and Shigella flexneri on oranges only. Thirty-one percent and 39% of the juice samples showed aerobic plate counts of ≥5.0 log CFU/ml and Escherichia coli counts of >3.0 log CFU/ml, respectively. These high counts may indicate poor sanitation and potential exposure to fecal contamination either in the raw materials or during the orange-crushing and juice-serving process. These data may be useful for a further risk assessment of Salmonella or Shigella in unpasteurized, freshly squeezed juice.