Risk Mitigation for Immunocompromised Consumers of Mucormycete Spoiled and Fermented Foods: Germane Guidance and Remaining Needs

Abstract

Mucoralean invasive fungal infections, while unusual among the general population, have a high mortality rate among immunocompromised individuals who become infected. They are also common spoilage organisms in cultured dairy products, some fresh produce, and baked goods. Additionally, Mucor and Rhizopus spp. are utilized in the production of traditional fermented foods including mold ripened cheeses and fermented soy products. The risk that consumption of these foods poses to immunocompromised consumers has been previously identified. However, actionable guidance on implementation of appropriate dietary restrictions and microbial specification targets for food manufacturers serving these populations is scarce and is limited by insufficient data regarding traceback analysis in cases of invasive fungal infections where food is the suspected transmission vector. Culture-dependent and molecular subtyping methods, including whole genome sequencing, will improve identification of the point source. In turn, the empirically determined information on root-cause can best direct the development of appropriate food safety policies and programs.

Biotic Environments Supporting the Persistence of Clinically Relevant Mucormycetes

“…are part of the production of traditional fermented foods such as mould ripened cheeses and fermented soy products. Snyder and Worobo make a distinction between food contamination with Mucorales and those introduced and propagated during food processing [29]. Consumption of these food items is a potential risk for immunocompromised patients.…”

“…Consumption of these food items is a potential risk for immunocompromised patients. It has been known for many years that R. oryzae readily contaminates grains, onions, various nuts, and stored seed potatoes [29].…”

“…They are well recognised as spoilage agents of dairy products, cheese and yogurt. Samples isolated from Chobani yogurt that was voluntarily recalled in September 2013 have been found to contain Mucor circinelloides, which is associated with infections in immune-compromised people, as reviewed in [29]. Some Mucorales are unspecified parasites of the sappy tissues of higher plants.…”

Nature Abhors a Vacuum: Highly Diverse Mechanisms Enable Spoilage Fungi to Disperse, Survive, and Propagate in Commercially Processed and Preserved Foods

“…A lack of scientific literature and direct evidence exists to generally establish fungi as etiological agents of foodborne illness from processed foods (in contrast to raw agricultural commodities) as either opportunistic invasive pathogens or as mycotoxin producers. However, additional research in this area that includes molecular subtyping in substantiating root‐cause of mycosis will help more concretely and quantitatively determine the risk fungi pose in these areas (Frisvad, ; Frisvad & Larsen, ; Snyder & Worobo ).…”

“…These molds are rarely toxigenic, as they lack systems for polyketide and nonribosomal peptide synthesis (PKS‐NRPS) that are common in ascomycetes. Some are aggressive opportunistic pathogens of humans, capable of causing invasive disease (Snyder & Worobo, ; Snyder et al., ). Mucoralean molds are prolific producers of airborne spores, and some tolerate low‐oxygen environments, which can make them formidable spoilage organisms.…”