Behaviour of the pathogen surrogates Listeria innocua and Clostridium sporogenes during production of parsley in fields fertilized with contaminated amendments

Abstract

The survival and transfer of Listeria innocua and Clostridium sporogenes, used as surrogates of the food borne pathogens Listeria monocytogenes and Clostridium botulinum, were quantitatively assessed under field conditions. In the soil, spores of C. sporogenes declined by less than 0.7 log cycles within 16 months and were detected on parsley leaves throughout the experiment. In contrast, L. innocua in the soil declined by 7 log cycles in 90 days and was detected on leaves in low numbers (>0.04 MPN g(-1)) during the first 30 days. Rates of decline in soil were similar in the laboratory at 20 degrees C for two strains of L. innocua and L. monocytogenes ; and in the field for L. innocua over two different years. L. innocua survived better in winter, indicating an important influence of temperature. The major cause of transfer of L. innocua from soil to parsley leaves was splashing due to rain and irrigation. As few as 1 CFU g(-1) Listeria in soil led to contamination of parsley leaves. Internalisation of Listeria through parsley roots was not observed. Under the conditions of soil and climate studied, a delay of 90 days between application of potentially contaminated fertilizer and harvest should be sufficient to eliminate L. monocytogenes.

The Growing Season, but Not the Farming System, Is a Food Safety Risk Determinant for Leafy Greens in the Mid-Atlantic Region of the United States

“…Splash-mediated soil dispersal was a potential contamination route for human-pathogenic bacteria onto fresh produce (78,79), and the transfer of foodborne pathogens to external produce surfaces via contact with contaminated soil has been reported (80,81). However, evidence also supports the notion that selection for phyllospheric microbial community members is largely plant regulated and less influenced by environmental factors such as water type (82) or airborne migration (83), which might explain why soiled leaves did not harbor significantly higher indicator bacterial counts.…”

Modeling of Spatially Referenced Environmental and Meteorological Factors Influencing the Probability ofListeriaSpecies Isolation from Natural Environments

“…Interestingly, precipitation increased the probability of isolation of Listeria spp. from soil, but it did not That is surprising, because it is generally considered that rain and water irrigation increase the probability of produce contamination with microorganisms (14). The probability of isolating Listeria spp.…”

Interaction between the Microbial Community and Invading Escherichia coli O157:H7 in Soils from Vegetable Fields

“…Many researchers have reported that soil microbial communities respond to the presence of heavy metals and organic pollutants (1)(2)(3)(4)(5)(6). Increasing numbers of studies in recent years have also been conducted on soil biopollution by pathogenic microorganisms, including viruses, protozoa, and bacteria such as Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes (7)(8)(9). E. coli O157: H7, a significant pathogen carried naturally by animals, has been shown to pose a significant threat to environmental safety and public health because of its low infective dose (as few as 10 cells) and its high pathogenicity in watery diarrhea, hemorrhagic colitis, hemorrhagic-uremic syndrome, thrombotic thrombocytopenic purpura, etc.…”