Transfer of Escherichia coli O157:H7 to Spinach by House Flies, Musca domestica (Diptera: Muscidae)

Abstract

Filth flies are known mechanical vectors of pathogenic bacteria in hospital and restaurant settings, but their role as vectors for disseminating microbes to plants has not been demonstrated. Escherichia coli O157:H7 deposition by flies onto spinach was studied using molecular, microbiological, and microscopy techniques. Relative quantitative polymerase chain reaction studies showed that bacteria acquired by flies from contaminated cattle manure and deposited in regurgitation spots on leaves survived and multiplied. Scanning electron microscopy of the regurgitation spots of flies exposed to manure inoculated with E. coli suggested the multiplication of bacteria-like organisms within the spots. This finding implies that the bacteria were active and is consistent with a hypothesis that regurgitation spots serve as a nutrition source allowing E. coli O157:H7 to survive on the spinach phylloplane. E. coli O157:H7 persisted on fly body surfaces up to 13 days after exposure to acquisition sources, suggesting that fly cuticular surfaces are conducive to the growth of this pathogen. These results are consistent with the hypothesis of bioenhanced transmission of human pathogens by house flies and suggest that filth flies may affect the microbial safety of fresh produce.

Interacciones entre Escherichia coli O157:H7 y Plantas Comestibles. ¿Se han Desarrollado Mecanismos de Internalización Bacteriana?

“…Also, flies can pick up E. coli O157:H7 from manure and deposit it onto the phylloplane of plants, where the bacteria can then colonise and multiply ). Despite such reports, the dissemination of this bacterium by flies to fresh produce requires further investigation, for it would seem to conflict with reports suggesting that E. coli O157:H7 can survive for only two to four days on a leaf surface (Wasala et al, 2013). Other studies report that this pathogen can survive on the phylloplane of spinach leaves for 14 days (Mitra et al, 2009).…”

“…It has been shown that if fresh produce is grown near livestock, these vectors can easily carry faecal contaminants to plants (Doyle and Erickson, 2012;Fletcher et al, 2013;Wasala et al, 2013). Also, flies can pick up E. coli O157:H7 from manure and deposit it onto the phylloplane of plants, where the bacteria can then colonise and multiply ).…”

“…These authors also claim that leaf surface bacterial colonization can increase over time. Meanwhile, Wasala et al (2013) suggest that leaf surface colonization, by the strain ATCC4388, does not increase when exposure time increases (vegetal tissue-bacteria).…”

“…Hence it is recommended, Por otra parte, muchos estudios han encontrado que las moscas , artrópodos, aves, mamíferos silvestres y reptiles (Wright et al, 2013) son otras fuentes importantes de transmisión de patógenos. Se ha demostrado que si las hortalizas se cultivan cerca de ganado, estos vectores pueden acarrear la contaminación fecal a las plantas (Doyle y Erickson, 2012;Fletcher et al, 2013;Wasala et al, 2013). Además, las moscas pueden recoger E. coli O157:H7 del estiércol y depositarla en el filoplano de las plantas, donde puede posteriormente colonizar el tejido y multiplicarse .…”

“…Además, las moscas pueden recoger E. coli O157:H7 del estiércol y depositarla en el filoplano de las plantas, donde puede posteriormente colonizar el tejido y multiplicarse . A pesar de estos resultados, la diseminación de la bacteria por medio de las moscas requiere más investigación, debido a que otros autores reportan que E. coli O157:H7 solo puede sobrevivir de dos a cuatro días en la superficie de una hoja (Wasala et al, 2013). Otros estudios reportan que este patógeno puede sobrevivir en el filoplano de hojas de espinaca durante 14 días (Mitra et al, 2009).…”