title: Cross-sectional survey of indicator and pathogenic bacteria on vegetables sold from Asian vendors at farmers' markets in northern California.
abstract: A cross-sectional survey was conducted during summer 2013 to determine the occurrence of Escherichia coli, fecal coliforms (FCs), E. coli O157:H7, and Salmonella on raw vegetable commodities common to Asian cuisine from 21 vendors or farmers at six farmers' markets in northern California. Based on 242 samples from six commodities (basil, yardlong beans, bitter squash, okra, squash stems and leaves, cilantro), 100% of samples had detectable FCs and 20% had detectable E. coli. The mean concentrations were 0.67 log CFU/g and 1.26 log CFU per bundle for E. coli and 4.00 log CFU/g and 6.26 log CFU per bundle for FCs. Vegetables irrigated with ground versus surface water contained lower concentrations of FCs, but this difference was not observed for E. coli. Yardlong beans, bitter squash, and okra had lower levels of FCs compared with basil, cilantro, and squash stems and leaves. Sixteen (6.6%) samples had detectable levels of Salmonella serovars (Newport, Enteritidis, Agona, and Worthington), with the majority of positives found in cilantro and squash stems and leaves. There was a twofold higher probability of Salmonella contamination in samples from growers or vendors who stated that they used organic farming practices compared with samples from those using conventional farming practices. Lastly, the concentrations of FC and E. coli bacteria were significantly associated with Salmonella contamination: for each additional 100 CFU/g or bundle, the probability of Salmonella contamination increased by ∼15 and ∼30%, respectively. None of the samples had detectable E. coli O157:H7.
authors.affiliation: Department of Food Science and Engineering, Jilin University, 5333 Xi'an Road, Changchun 130062, People's Republic of China.
authors.forename: Fengguang
authors.initials: F
authors.lastname: Pan
authors.affiliation: Western Institute for Food Safety and Security, 1477 Drew Avenue, Suite 101, Davis, California 95616, USA. xdli@ucdavis.edu.
authors.forename: Xunde
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Population Health and Reproduction, 1089 Veterinary Medicine Drive, Davis, California 95616, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Carabez
authors.affiliation: Department of Population Health and Reproduction, 1089 Veterinary Medicine Drive, Davis, California 95616, USA.
authors.forename: Guy
authors.initials: G
authors.lastname: Ragosta
authors.affiliation: Department of Population Health and Reproduction, 1089 Veterinary Medicine Drive, Davis, California 95616, USA.
authors.forename: Kristine L
authors.initials: KL
authors.lastname: Fernandez
authors.affiliation: Department of Population Health and Reproduction, 1089 Veterinary Medicine Drive, Davis, California 95616, USA.
authors.forename: Elaine
authors.initials: E
authors.lastname: Wang
authors.affiliation: Department of Population Health and Reproduction, 1089 Veterinary Medicine Drive, Davis, California 95616, USA.
authors.forename: Anyarat
authors.initials: A
authors.lastname: Thiptara
authors.affiliation: Department of Population Health and Reproduction, 1089 Veterinary Medicine Drive, Davis, California 95616, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Antaki
authors.affiliation: Department of Food Science and Engineering, Jilin University, 5333 Xi'an Road, Changchun 130062, People's Republic of China; Western Institute for Food Safety and Security, 1477 Drew Avenue, Suite 101, Davis, California 95616, USA; Department of Population Health and Reproduction, 1089 Veterinary Medicine Drive, Davis, California 95616, USA. ratwill@ucdavis.edu.
authors.forename: Edward R
authors.initials: ER
authors.lastname: Atwill
mesh_terms: D002140:California; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D003430:Cross-Sectional Studies; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology; D012475:Salmonella / Q000254:growth & development / Q000302:isolation & purification*; D014675:Vegetables / Q000382:microbiology*