Nonculturable Response of Animal Enteropathogens in the Agricultural Environment and Implications for Food Safety

Abstract

Concerns about animal enteropathogen contamination of fresh horticultural products have,increased worldwide and are mainly due to the ability of bacteria to survive under stress conditions in the agricultural environment and during raw-vegetable processing. This review challenges the idea that the viable but nonculturable phenomenon that has been proven to occur in plant-associated environments contributes to human pathogen survival and might be correlated with foodborne infection. Factors associated with the nonculturable response of bacteria in the field and during postharvest processing and distribution are discussed, specifically for the most common animal enteropathogens linked with the consumption of raw products: Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and Shigella spp. The accurate detection of live bacterial populations is essential for pathogen screening in food and environmental safety control and in epidemiological analysis and may have to be considered for identification of critical control points at the time of food inspection.

Induction of Viable but Nonculturable Escherichia coli O157:H7 in the Phyllosphere of Lettuce: a Food Safety Risk Factor

“…The VBNC state is thought to be a transient physiological phase in which cells switch off activities typical for growing organisms but maintain a low level of metabolic activity without remaining culturable on routine microbiological media (26,31,39). There is compelling evidence that the nonculturable response occurs in different environmental and food matrices, but the significance of the passage into a dormancy stage and recovery is controversial (14).…”

Inactivation of Foodborne Pathogens and Their Surrogates on Fresh and Frozen Strawberries Using Gaseous Ozone

“…10 3 CFU/g. Concerns regarding stressed cells and nonculturable response should be further investigated to confirm the inactivation effect of gaseous ozone treatment (Dinu et al, 2009). For viruses, it was reported that ozone damaged the protein capsid but the RNA remained intact after the treatment (Pascual et al, 2007;Zhang et al, 2011;Predmore et al, 2015).…”

Using ATP tests for assessment of hygiene risks

“…The passing of pathogenic bacteria cells (eg Salmonella sp, Campylobacter jejuni, Vibrio vulnificus, Vibrio parahaemolyticus, Yersinia enterocolitica and Escherichia coli) into VBNC forms is particularly dangerous, as they remain active all the time. Additionally, they have higher virulence than the cells which are not influenced by the stressors [39,40].…”

“…Consequently, classic methods for detection and qualitative determination of strains forming the biofilm may be insufficient. The presence of microbes in the VBNC state in a given environment can be detected with methods of cell viability determination, such as the ATP assay, and without using traditional agar plating techniques [39].…”