title: Incidence and behavior of Salmonella and Escherichia coli on whole and sliced zucchini squash (Cucurbitapepo) fruit.
abstract: The incidence of coliform bacteria (CB), thermotolerant coliforms (TC), Escherichia coli, and Salmonella was determined for zucchini squash fruit. In addition, the behavior of four serotypes of Salmonella and a cocktail of three E. coli strains on whole and sliced zucchini squash at 25+/-2 degrees C and 3 to 5 degrees C was tested. Squash fruit was collected in the markets of Pachuca city, Hidalgo State, Mexico. CB, TC, E. coli, and Salmonella were detected in 100, 70, 62, and 10% of the produce, respectively. The concentration ranged from 3.8 to 7.4 log CFU per sample for CB, and >3 to 1,100 most probable number per sample for TC and E. coli. On whole fruit stored at 25+/-2 degrees C or 3 to 5 degrees C, no growth was observed for any of the tested microorganisms or cocktails thereof. After 15 days at 25+/-2 degrees C, the tested Salmonella serotypes had decreased from an initial inoculum level of 7 log CFU to <1 log, and at 3 to 5 degrees C they decreased to approximately 2 log. Survival of E. coli was significantly greater than for the Salmonella strains at the same times and temperatures; after 15 days, at 25+/-2 degrees C E. coli cocktail strains had decreased to 3.4 log CFU per fruit and at 3 to 5 degrees C they decreased to 3.6 log CFU per fruit. Both the Salmonella serotypes and E. coli strains grew when inoculated onto sliced squash: after 24 h at 25+/-2 degrees C, both bacteria had grown to approximately 6.5 log CFU per slice. At 3 to 5 degrees C, the bacterial growth was inhibited. The squash may be an important factor contributing to the endemicity of Salmonella in Mexico.
authors.affiliation: Centro de Investigaciones Químicas, Instituto de Ciencias Básicas e Ingeniería, Universidad Autónoma del Estado de Hidalgo, Centro Universitario, Carretera Pachuca-Tulancingo Km. 4.5, Mineral de la reforma, Hidalgo, C.P. 42183, Mexico. jcastro@uaeh.edu.mx
authors.forename: Javier
authors.initials: J
authors.lastname: Castro-Rosas
authors.forename: Eva María
authors.initials: EM
authors.lastname: Santos López
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Gómez-Aldapa
authors.forename: Cesar Abelardo
authors.initials: CA
authors.lastname: González Ramírez
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Villagomez-Ibarra
authors.forename: Alberto José
authors.initials: AJ
authors.lastname: Gordillo-Martínez
authors.forename: Angélica Villarruel
authors.initials: AV
authors.lastname: López
authors.forename: M
authors.initials: M
authors.lastname: del Refugio Torres-Vitela
mesh_terms: D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D028464:Cucurbita / Q000382:microbiology*; D004926:Escherichia coli / Q000145:classification / Q000254:growth & development* / Q000302:isolation & purification; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006801:Humans; D015994:Incidence; D008800:Mexico / Q000453:epidemiology; D012475:Salmonella / Q000145:classification / Q000254:growth & development* / Q000302:isolation & purification; D012703:Serotyping; D013696:Temperature