Sources and contamination routes of microbial pathogens to fresh produce during field cultivation: A review

Abstract

Foodborne illness resulting from the consumption of contaminated fresh produce is a common phenomenon and has severe effects on human health together with severe economic and social impacts. The implications of foodborne diseases associated with fresh produce have urged research into the numerous ways and mechanisms through which pathogens may gain access to produce, thereby compromising microbiological safety. This review provides a background on the various sources and pathways through which pathogenic bacteria contaminate fresh produce; the survival and proliferation of pathogens on fresh produce while growing and potential methods to reduce microbial contamination before harvest. Some of the established bacterial contamination sources include contaminated manure, irrigation water, soil, livestock/ wildlife, and numerous factors influence the incidence, fate, transport, survival and proliferation of pathogens in the wide variety of sources where they are found. Once pathogenic bacteria have been introduced into the growing environment, they can colonize and persist on fresh produce using a variety of mechanisms. Overall, microbiological hazards are significant; therefore, ways to reduce sources of contamination and a deeper understanding of pathogen survival and growth on fresh produce in the field are required to reduce risk to human health and the associated economic consequences.

Microbial Contamination of Fresh Produce: What, Where, and How?

“…The plant morphology may also be important—for example, water can be retained on lettuce leaves, which increases the potential for contamination. Crop fertilization with contaminated manure has been associated with microbial disease outbreaks linked to consumption of leafy green vegetables (Alegbeleye et al., ; Julien‐Javaux et al., ). Contamination or pathogen internalization of lettuce plants grown on contaminated soil (Bernstein, Sela, & Neder‐Lavon, ), or soil amended with contaminated growth media has been reported (Murphy, Gaffney, Fanning, & Burgess, ).…”

“…Both rain and irrigation water droplets have been shown to carry over soil particles to the surface of plants, leading to produce contamination (Allende et al., ; Girardin et al., ). Direct contact of plant surfaces with manure is also a source of contamination (Alegbeleye et al., ).…”

“…Microbial contamination of fresh produce has been widely reviewed in the literature (Alegbeleye, Singleton, & Sant'Ana, 2018;Berger et al, 2010;Gutierrez-Rodriguez & Adhikari, 2018;Julien-Javaux, Gérard, Campagnoli & Zuber, 2019;Miceli & Settanni, 2019;Mritunjay & Kumar, 2015). When considering the farm-to-fork chain, microbial contamination of fresh produce can occur at multiple steps (Matthews, 2013).…”

The Scent of the Fly

“…The occurrence of Z4-11Al in nature is incompletely known and its possible role in humans remains unclear. Z4-11Al may merely be reminiscent of other food aldehydes, or it might avert ingestion of fruit that is infested with vinegar flies, which can be contaminated with microbes vectored by flies (Alegbeleye et al 2018).…”

Survival and internalization of Salmonella and Escherichia coli O157:H7 sprayed onto different cabbage cultivars during cultivation in growth chambers

“…Hence, it is vital to prevent contamination both in pre‐harvest and post‐harvest operations. In the case of pre‐harvest operations, several sources have been suggested as vehicles of enteric pathogen contamination including: irrigation water, domestic animal manure or improperly composted animal manure, water run‐off from livestock operations, waste from domestic and wild animals, and trophic interactions between plants and plant foragers, such as birds and insects . Nevertheless, even when outbreaks have been traced back to a farm, documenting the actual source of contamination has been rare given the time lag between the time at which the crop was harvested and the time at which the outbreaks are detected and epidemiologically investigated.…”