Ingested Salmonella enterica, Cronobacter sakazakii, Escherichia coli O157:H7, and Listeria monocytogenes: transmission dynamics from adult house flies to their eggs and first filial (F1) generation adults.

Monica Pava-Ripoll,Ben D Tall,Rachel E Goeriz Pearson,Christine E Keys,George C Ziobro,Amy K Miller

doi:10.1186/s12866-015-0478-5

Monica Pava-Ripoll, Ben D Tall + Show 4 more

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https://doi.org/10.1186/s12866-015-0478-5

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Abstract

BackgroundThe mechanical transmission of pathogenic bacteria by synanthropic filth flies is widely recognized. While many studies report the fate and the temporospatial distribution of ingested foodborne bacteria by filth flies, there is little evidence about the transmission dynamics of ingested foodborne bacteria by adult house flies (Musca domestica) to their progeny. In this study, we fed parental house fly adults with food contaminated with low, medium, and high concentrations of Salmonella enterica, Cronobacter sakazakii, Escherichia coli O157:H7, and Listeria monocytogenes and evaluated the probability of transmission of these pathogens to house fly eggs and the surface and the alimentary canal of their first filial (F1) generation adults.ResultsAll foodborne pathogens were present in samples containing pooled house fly eggs. The probability of transmission was higher after parental house flies ingested food containing medium bacterial loads. Cronobacter sakazakii was 16, 6, and 3 times more likely to be transmitted to house fly eggs than S. enterica, E. coli O157:H7, and L. monocytogenes, respectively. Only S. enterica and C. sakazakii were transmitted to F1 generation adults and their presence was 2.4 times more likely on their body surfaces than in their alimentary canals. The highest probabilities of finding S. enterica (60 %) and C. sakazakii (28 %) on newly emerged F1 adults were observed after parental house flies ingested food containing medium and high levels of these pathogens, respectively.ConclusionOur study demonstrates that adult house flies that fed from food contaminated with various levels of foodborne bacteria were able to transmit those pathogens to their eggs and some were further transmitted to newly emerged F1 generation adults, enhancing the vector potential of these insects. Understanding the type of associations that synanthropic filth flies establish with foodborne pathogens will help to elucidate transmission mechanisms and possible ways to mitigate the spread of foodborne pathogens.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-015-0478-5) contains supplementary material, which is available to authorized users.

Highlights

The mechanical transmission of pathogenic bacteria by synanthropic filth flies is widely recognized
The objective of this study was to estimate the probability of transmission of four foodborne bacteria (S. enterica, C. sakazakii, E. coli O157:H7, and L. monocytogenes ) to the progeny of the common house fly, Musca domestica (Linneaus) (Diptera: Muscidae), after parental house flies were fed with food contaminated with low, medium, and high levels of each bacterium
All parental house flies used in our experiments were observed feeding from contaminated food and the presence of each pathogen was confirmed from all alimentary canals dissected from randomly selected parental females

Summary

Introduction

The mechanical transmission of pathogenic bacteria by synanthropic filth flies is widely recognized. The biology and ecology of synanthropic insects like flies make them efficient carriers of disease-causing microorganisms Their breeding habits, mode of feeding and indiscriminate traveling between decomposed waste and human settings highly contribute to the dissemination of pathogens in the environment. The FDA’s regulatory action criteria for filth includes a five-attribute profile that needs to be fulfilled before including a particular fly species as reasonably likely to act as a contributing factor of the spread of foodborne pathogens. These five attributes are synanthropy, endophily, communicative behavior, attraction to filth and human food, and the isolation of pathogens from wild populations [1, 2]. Other fly species fulfilling at least four of those attributes are considered opportunistic pests and their presence in food and/or food-related environments is an indication of insanitation [2]

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