Survival of Salmonella enterica in Dried Turkey Manure and Persistence on Spinach Leaves

Abstract

Concerns about the microbiological safety of fresh produce have attracted attention in the past three decades due to multiple foodborne outbreaks. Animal manure contaminated with enteric pathogens has been identified as an important preharvest pathogen source. This study investigated the survival of Salmonella enterica in dust particles of dehydrated turkey manure and how association with manure dust may enhance the survival of salmonellae on leafy greens in the field. The survival of a cocktail of multiple Salmonella serotypes in the dried fecal material of various particle sizes (125 to 500 μm) was examined at varying moisture contents (5, 10, and 15%). Survival times of the pathogen were inversely related to moisture content and particle size of manure dust, with viable Salmonella still detectable for up to 291 days in the smallest particle size (125 μm) with 5% moisture. Association with manure dust particles increased the survival of Salmonella when subjected to UV light both under laboratory conditions and on the surface of spinach leaves in a greenhouse setting. The results of this study suggest that aerosolized manure particles could be a potential vehicle for Salmonella dispersal to leafy greens if the microorganism is present in the dry manure.

Salmonella enterica in Soils Amended with Heat-Treated Poultry Pellets Survived Longer than Bacteria in Unamended Soils and More Readily Transferred to and Persisted on Spinach

“…Other studies have investigated the transfer and survival of Salmonella enterica on produce from dried contaminated manure or irrigation water. Dried turkey manure dust inoculated with three S. enterica strains (S. Typhimurium CVM-98 and LT-2 and S. Enteritidis KPL 13076) was applied to both the adaxial and abaxial surfaces of spinach leaves and showed an approximately 2-log reduction from an initial level of 3.5 to 4.0 log CFU/g in 14 days (31). In the same study, inoculation of spinach leaves with contaminated water at 6.5 to 7.0 log CFU/g showed an approximately 5-log reduction in 14 days, with substantial reduction observed on the adaxial surfaces of spinach leaves.…”

“…from soil to leafy greens are lacking. However, the transfer of manure dust particles containing Salmonella enterica to leaves of leafy green plants have shown various degrees of survival up to 14 days (31). During commercial spinach production, leaves may be harvested twice from the same plants, but the likelihood of Salmonella transfer from soil to leaves at these different harvest times is lacking.…”

Solanum lycopersicum (tomato) hosts robust phyllosphere and rhizosphere bacterial communities when grown in soil amended with various organic and synthetic fertilizers

“…Amendments could introduce beneficial microorganisms that directly or indirectly reduce plant pathogen and insect damage (Hadar and Papadopoulou, 2012;Liu et al, 2007;Mehta et al, 2014), or human pathogens that could undermine food safety (Islam et al, 2005;Mootian et al, 2009;Oni et al, 2015). Investigations into the 6 influence of soil amendment application on plant microbiota have focused primarily on the rhizosphere.…”

Survival of Escherichia coli in Manure-Amended Soils Is Affected by Spatiotemporal, Agricultural, and Weather Factors in the Mid-Atlantic United States

“…Manure dust originating from a cattle feedlot can transfer E. coli O157:H7 to leafy green crops 180 m away (15). Manure dust can also serve to protect bacterial pathogens such as S. enterica from inactivation by UV components of sunlight, which can extend bacterial survival on leaves of growing spinach leaves (16). Human exposure to untreated animal manure or insect vectors can also lead to potential cases of infection with enteric pathogens (17,18).…”