Biofilm formation by enteric pathogens and its role in plant colonization and persistence

Abstract

The significant increase in foodborne outbreaks caused by contaminated fresh produce, such as alfalfa sprouts, lettuce, melons, tomatoes and spinach, during the last 30 years stimulated investigation of the mechanisms of persistence of human pathogens on plants. Emerging evidence suggests that Salmonella enterica and Escherichia coli, which cause the vast majority of fresh produce outbreaks, are able to adhere to and to form biofilms on plants leading to persistence and resistance to disinfection treatments, which subsequently can cause human infections and major outbreaks. In this review, we present the current knowledge about host, bacterial and environmental factors that affect the attachment to plant tissue and the process of biofilm formation by S. enterica and E. coli, and discuss how biofilm formation assists in persistence of pathogens on the plants. Mechanisms used by S. enterica and E. coli to adhere and persist on abiotic surfaces and mammalian cells are partially similar and also used by plant pathogens and symbionts. For example, amyloid curli fimbriae, part of the extracellular matrix of biofilms, frequently contribute to adherence and are upregulated upon adherence and colonization of plant material. Also the major exopolysaccharide of the biofilm matrix, cellulose, is an adherence factor not only of S. enterica and E. coli, but also of plant symbionts and pathogens. Plants, on the other hand, respond to colonization by enteric pathogens with a variety of defence mechanisms, some of which can effectively inhibit biofilm formation. Consequently, plant compounds might be investigated for promising novel antibiofilm strategies.

Comparable levels of microbial contamination in soil and on tomato crops after drip irrigation with treated wastewater or potable water

“…This work adds to increasing evidence, such as molecular fingerprinting of E. coli in water and crops (Forslund et al, 2012), showing that irrigation with TWW may hold promise from a microbial pathogen standpoint. Controlled studies have shown that pathogens could invade the roots from the soil and colonize plants ( Barak and Liang, 2008;Barak et al, 2011;Yaron and Römling, 2014), yet the high bacterial counts introduced in these studies (10 7 -10 9 ) were never encountered in the TWW or soil in the present study (Table 2). Thus, further analyses should be conducted by agronomists and public health officials aiming of test the irrigation of TWW on a brad array of soil types and vegetables.…”

Alternative disinfection methods to chlorine for use in the fresh-cut industry

“…However, despite the increased awareness of food safety issues, the occurrence of foodborne disease outbreaks related to these products is constantly increasing (Gilbert & McBain, 2003;Ölmez & Kretzschmar, 2009;Vitale & Schillaci, 2016) with several pathogenic bacteria associated, such as Listeria monocytogenes, Clostridium botulinum, Bacillus cereus, Escherichia coli O157:H7 and Salmonella spp. (Olaimat & Holley, 2012;Seiber, 2012;Warriner, Huber, Namvar, Fan, & Dunfield, 2009), as well as viruses (norovirus and hepatitis A) and protozoa (Cryptosporidium parvum) (Berger, Sodha, Shaw, Griffin, Pink, Hand, & Frankel, 2010;Yaron & Romling, 2014).…”

“…are the two microorganisms linked to the largest foodborne outbreaks and consequent human infections (Warriner et al, 2009;Yaron & Romling, 2014). a 2.58 log CFU/cm 2 reduction.…”

Development of an Avirulent Salmonella Surrogate for Modeling Pathogen Behavior in Pre- and Postharvest Environments

“…Persistence in well water after 7 days was 3.3 Ϯ 0.3 log CFU/ml for 14028 and 3.8 Ϯ 0.5 log CFU/ml for MHM112. ness of a surrogate (17), since biofilms facilitate environmental persistence (38). Therefore, biofilm formation on polystyrene and polypropylene was examined for the surrogate strain and the wild type, as well as for individual mutants.…”