title: Relationships among hygiene indicators and enteric pathogens in irrigation water, soil and lettuce and the impact of climatic conditions on contamination in the lettuce primary production.
abstract: Eight Belgian lettuce farms located in the West Flanders were sampled to establish the relationships between levels of indicator bacteria, detection of enteric zoonotic pathogens and the temperature and precipitation during primary production. Pathogenic bacteria (PCR EHEC positives, Salmonella spp. or Campylobacter spp.) and indicator bacteria (total psychrotrophic aerobic plate count (TPAC), total coliforms, Escherichia coli, enterococci) were determined over a period of one and a half year from seedling leaves, peat-soil of the seedling, lettuce crops, field soil and irrigation water. Neither Salmonella isolates nor PCR EHEC signals were detected from lettuce although one out of 92 field soil samples contained Salmonella spp. and five soil samples provided PCR positives for EHEC virulence factors (vt1 or vt2 and eae gene). A low prevalence of Campylobacter (8/88) was noted in lettuce. It was shown that irrigation water is a major risk factor with regard to the bacterial contamination of the fresh produce as the water samples showed on a regular basis E. coli presence (59.2% of samples≥1CFU/100ml) and occasionally detection of pathogens (25%, n=30/120), in particular Campylobacter spp. The highest correlations between indicator bacteria, pathogens, temperature and the amount of precipitation were observed for the water samples in contrast to the soil or lettuce samples where no correlations were observed. The high correlations between E. coli, total coliforms and enterococci in the water implicated redundancy between analyses. Presence of elevated levels of E. coli increased the probability for the presence of pathogens (Campylobacter spp., EHEC and Salmonella spp.), but had a low to moderate predictive value on the actual presence of pathogens. The presence of pathogens and indicator bacteria in the water samples showed a seasonal effect as they tend to be more present during the months with higher temperature.
authors.affiliation: Laboratory of Food Microbiology and Food Preservation, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 B-Ghent, Belgium; Laboratory of Food Microbiology and -Biotechnology, Department of Industrial Biological Sciences, Faculty of Bioscience Engineering, Ghent University, Campus Kortrijk, Graaf Karel de Goedelaan 5, B-8500 Kortrijk, Belgium.
authors.forename: Kevin
authors.initials: K
authors.lastname: Holvoet
authors.affiliation: Laboratory of Food Microbiology and -Biotechnology, Department of Industrial Biological Sciences, Faculty of Bioscience Engineering, Ghent University, Campus Kortrijk, Graaf Karel de Goedelaan 5, B-8500 Kortrijk, Belgium. Electronic address: imca.sampers@ugent.be.
authors.forename: Imca
authors.initials: I
authors.lastname: Sampers
authors.affiliation: INAGRO, Provincial Research and Advisory Center for Agriculture and Horticulture, Ieperseweg 87, B-8800 Rumbeke-Beitem, Belgium.
authors.forename: Marleen
authors.initials: M
authors.lastname: Seynnaeve
authors.affiliation: Laboratory of Food Microbiology and Food Preservation, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000 B-Ghent, Belgium.
authors.forename: Mieke
authors.initials: M
authors.lastname: Uyttendaele
mesh_terms: D000383:Agriculture; D001419:Bacteria / Q000302:isolation & purification; D018407:Bacterial Physiological Phenomena; D002980:Climate; D004783:Environmental Microbiology; D005516:Food Microbiology; D006920:Hygiene; D018545:Lactuca / Q000382:microbiology*; D012621:Seasons; D012988:Soil Microbiology; D014871:Water Microbiology
keywords: Climate parameters; Indicator bacteria; Lettuce; Pathogens; Primary production; Seasonality