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Agricultural and management practices and bacterial contamination in greenhouse versus open field lettuce production.

Holvoet K, Sampers I, Seynnaeve M, Jacxsens L, Uyttendaele M - Int J Environ Res Public Health (2014)

Bottom Line: The aim of this study was to gain insight into potential differences in risk factors for microbial contamination in greenhouse versus open field lettuce production.These data were combined with results of analysis on the levels of Escherichia coli as a fecal indicator organism and the presence of enteric bacterial pathogens on both lettuce crops and environmental samples.These results indicate the need for further elaboration of specific guidelines and control measures for leafy greens with regard to microbial hazards.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Food Microbiology and Food Preservation, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent B-9000, Belgium. kevin.holvoet@ugent.be.

ABSTRACT
The aim of this study was to gain insight into potential differences in risk factors for microbial contamination in greenhouse versus open field lettuce production. Information was collected on sources, testing, and monitoring and if applicable, treatment of irrigation and harvest rinsing water. These data were combined with results of analysis on the levels of Escherichia coli as a fecal indicator organism and the presence of enteric bacterial pathogens on both lettuce crops and environmental samples. Enterohemorragic Escherichia coli (EHEC) PCR signals (vt1 or vt2 positive and eae positive), Campylobacter spp., and Salmonella spp. isolates were more often obtained from irrigation water sampled from open field farms (21/45, 46.7%) versus from greenhouse production (9/75, 12.0%). The open field production was shown to be more prone to fecal contamination as the number of lettuce samples and irrigation water with elevated E. coli was significantly higher. Farmers comply with generic guidelines on good agricultural practices available at the national level, but monitoring of microbial quality, and if applicable appropriateness of water treatment, or water used for irrigation or at harvest is restricted. These results indicate the need for further elaboration of specific guidelines and control measures for leafy greens with regard to microbial hazards.

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(A) Comparison of E. coli distribution between greenhouse farms (gh) and open field farms (of) for seedling soil, mature plant soil, lettuce, and water. (B) Comparison of E. coli distribution between individual greenhouse farms (f1, f2, f3, f4). (C) Comparison of E. coli distribution between individual open field farms (f5, f6, f7, f8). The P-value is shown after the designation.
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ijerph-12-00032-f003: (A) Comparison of E. coli distribution between greenhouse farms (gh) and open field farms (of) for seedling soil, mature plant soil, lettuce, and water. (B) Comparison of E. coli distribution between individual greenhouse farms (f1, f2, f3, f4). (C) Comparison of E. coli distribution between individual open field farms (f5, f6, f7, f8). The P-value is shown after the designation.

Mentions: For the peat-soil of the seedlings and the samples of the field soil, no difference in E. coli class was found between the greenhouse and the open field farms (P > 0.05, FET) (Figure 3A). In contrast, the E. coli load of the lettuce and the water was significantly different between the two production systems (P < 0.05, FET); in approximately 99% of the greenhouse lettuce samples, no E. coli was enumerated (< 10 cfu/g) in contrast to 90% of the open field farms (Table 2, Figure 3A). In 39.2% of the greenhouse water samples, E. coli was below the detection limit (< 1 cfu/100 mL), while 91.1% and 46.7% of the water samples of the open field farms were higher than 1 log CFU/100 ml and 2 log CFU/100 mL, respectively. The TPAC of the lettuce was significantly higher for the greenhouse farms (median 6.3 log CFU/g) compared to the open field farms (median 6.0 log CFU/g) (P < 0.05, t-test) (Table 2). Nevertheless, the microbiological relevance of a 0.3 log difference might be limited in terms of microbial quality.


Agricultural and management practices and bacterial contamination in greenhouse versus open field lettuce production.

Holvoet K, Sampers I, Seynnaeve M, Jacxsens L, Uyttendaele M - Int J Environ Res Public Health (2014)

(A) Comparison of E. coli distribution between greenhouse farms (gh) and open field farms (of) for seedling soil, mature plant soil, lettuce, and water. (B) Comparison of E. coli distribution between individual greenhouse farms (f1, f2, f3, f4). (C) Comparison of E. coli distribution between individual open field farms (f5, f6, f7, f8). The P-value is shown after the designation.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4306849&req=5

ijerph-12-00032-f003: (A) Comparison of E. coli distribution between greenhouse farms (gh) and open field farms (of) for seedling soil, mature plant soil, lettuce, and water. (B) Comparison of E. coli distribution between individual greenhouse farms (f1, f2, f3, f4). (C) Comparison of E. coli distribution between individual open field farms (f5, f6, f7, f8). The P-value is shown after the designation.
Mentions: For the peat-soil of the seedlings and the samples of the field soil, no difference in E. coli class was found between the greenhouse and the open field farms (P > 0.05, FET) (Figure 3A). In contrast, the E. coli load of the lettuce and the water was significantly different between the two production systems (P < 0.05, FET); in approximately 99% of the greenhouse lettuce samples, no E. coli was enumerated (< 10 cfu/g) in contrast to 90% of the open field farms (Table 2, Figure 3A). In 39.2% of the greenhouse water samples, E. coli was below the detection limit (< 1 cfu/100 mL), while 91.1% and 46.7% of the water samples of the open field farms were higher than 1 log CFU/100 ml and 2 log CFU/100 mL, respectively. The TPAC of the lettuce was significantly higher for the greenhouse farms (median 6.3 log CFU/g) compared to the open field farms (median 6.0 log CFU/g) (P < 0.05, t-test) (Table 2). Nevertheless, the microbiological relevance of a 0.3 log difference might be limited in terms of microbial quality.

Bottom Line: The aim of this study was to gain insight into potential differences in risk factors for microbial contamination in greenhouse versus open field lettuce production.These data were combined with results of analysis on the levels of Escherichia coli as a fecal indicator organism and the presence of enteric bacterial pathogens on both lettuce crops and environmental samples.These results indicate the need for further elaboration of specific guidelines and control measures for leafy greens with regard to microbial hazards.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Food Microbiology and Food Preservation, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, Ghent B-9000, Belgium. kevin.holvoet@ugent.be.

ABSTRACT
The aim of this study was to gain insight into potential differences in risk factors for microbial contamination in greenhouse versus open field lettuce production. Information was collected on sources, testing, and monitoring and if applicable, treatment of irrigation and harvest rinsing water. These data were combined with results of analysis on the levels of Escherichia coli as a fecal indicator organism and the presence of enteric bacterial pathogens on both lettuce crops and environmental samples. Enterohemorragic Escherichia coli (EHEC) PCR signals (vt1 or vt2 positive and eae positive), Campylobacter spp., and Salmonella spp. isolates were more often obtained from irrigation water sampled from open field farms (21/45, 46.7%) versus from greenhouse production (9/75, 12.0%). The open field production was shown to be more prone to fecal contamination as the number of lettuce samples and irrigation water with elevated E. coli was significantly higher. Farmers comply with generic guidelines on good agricultural practices available at the national level, but monitoring of microbial quality, and if applicable appropriateness of water treatment, or water used for irrigation or at harvest is restricted. These results indicate the need for further elaboration of specific guidelines and control measures for leafy greens with regard to microbial hazards.

Show MeSH
Related in: MedlinePlus