title: 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.
abstract: BACKGROUND
  The 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.
  
  
  RESULTS
  All 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.
  
  
  CONCLUSIONS
  Our 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.
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Food Safety, 5100 Paint Branch Pkwy, College Park, MD, 20740, USA. Monica.Pava-Ripoll@fda.hhs.gov.
authors.forename: Monica
authors.initials: M
authors.lastname: Pava-Ripoll
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Food Safety, 5100 Paint Branch Pkwy, College Park, MD, 20740, USA. Rachel.Pearson@fda.hhs.gov.
authors.forename: Rachel E Goeriz
authors.initials: RE
authors.lastname: Pearson
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Food Safety, 5100 Paint Branch Pkwy, College Park, MD, 20740, USA. Amy.Miller@fda.hhs.gov.
authors.forename: Amy K
authors.initials: AK
authors.lastname: Miller
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Applied Research and Safety Assessment, 8301 Muirkirk Rd, Laurel, MD, 20708, USA. Ben.Tall@fda.hhs.gov.
authors.forename: Ben D
authors.initials: BD
authors.lastname: Tall
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Regulatory Science, 5100 Paint Branch Pkwy, College Park, MD, 20740, USA. Christine.Keys@fda.hhs.gov.
authors.forename: Christine E
authors.initials: CE
authors.lastname: Keys
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Food Safety, 5100 Paint Branch Pkwy, College Park, MD, 20740, USA. George.Ziobro@fda.hhs.gov.
authors.forename: George C
authors.initials: GC
authors.lastname: Ziobro
mesh_terms: D000818:Animals; D001424:Bacterial Infections / Q000635:transmission*; D004064:Digestive System / Q000382:microbiology; D004755:Enterobacteriaceae / Q000302:isolation & purification*; D005506:Food Contamination; D006793:Houseflies / Q000382:microbiology*; D008089:Listeria monocytogenes / Q000302:isolation & purification*; D015053:Zygote / Q000382:microbiology*